target-proposal-6 by fanzhongqing

VIEWS: 7 PAGES: 30

									                                                                                                 June 2011




  Proposal for continuation of generic high power target
                         studies


                                         A. Bungau, C. Bungau
                   University of Huddersfield, Queensgate, Huddersfield, HD1 3DH, UK


D. Bellenger, J. R. J. Bennett, S. Brooks, O. Caretta, T. Davenne, C. J. Densham, T. R. Edgecock, M.
     Fitton, D. Jenkins, L. Jones, P. Loveridge, Y. Ma, J. O'Dell, E. Quinn, M. Rooney, D. Wilcox
            STFC Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, UK


                                       C. N. Booth, G. P. Skoro
            Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, UK


                                         J. J. Back, S. B. Boyd
                  Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
Executive summary
Over recent years, a significant amount of expertise in the design, construction and operation of targets
for high power proton accelerators has been developed in the UK, largely funded by STFC. This has
evolved mainly from work on ISIS target stations 1 and 2, the Neutrino Factory, neutrino superbeam
facilities such as T2K and design studies for Accelerator Driven Sub-critical Reactors and the ESS. This
proposal has two main objectives. The first is to bring together the different groups that have done this
work into a single entity, thereby creating a World-leading high power target group in the UK. The
second is to utilise the experience and skills of the group created to study, in a generic manner, targets
for a variety of applications.
The applications to be studied range from fundamental physics, through neutron spallation to a number
in the STFC Grand Challenge areas. They are:
   Upgrades to the ISIS target stations in line with potential upgrades to the accelerators and
    contributions to the development of the target for the European Spallation Source.
   A study of the target and beam window for an Accelerator Driven Sub-critical Reactor as part of a
    Design Study being run by Jacob Engineering Group, the ADTR project.
   The design and tests of solid and liquid lithium targets for the production of thermal and epi-thermal
    neutrons for three applications. These are Boron Neutron Capture Therapy, a possible therapy for
    treating currently incurable cancers, the production of molybdenum 99 as a source of technetium 99,
    the most commonly used radioactive tracer in medicine, and scanning cargo containers for shielded
    nuclear material.
   The design of targets for possible future neutrino superbeam projects in Europe, Japan and the US.
   Completion of work on a solid target option for a Neutrino Factory and the demonstration that this is a
    viable alternative to the current liquid mercury baseline.
   The design of targets for possible muon to electron conversion experiments in Japan and the US.
In addition, it is planned to develop generic tools for high power target development and operation and to
continue studies of a novel powder jet target technology.
Each of the targets is beyond the state-of-the-art, but many of the issues that must be solved for them
are very similar, allowing a generic approach to the work. Further, the team being created here has a
broad range of skills, from a theoretical understanding of beam interactions with materials, through
modelling of these interactions, including particle production and thermal shock, into the engineering of
targets and target stations, including cooling, shielding and remote handling. Further, members of the
team have been involved the design, construction and operation of targets that are currently in use. This
broad range will be available to deal with the issues for each target, thereby facilitating solutions to the
difficult problems that many of them pose.
Here we propose a four year programme to undertake this work, which includes design, modelling,
prototyping and testing both of targets and target stations. This will involve approximately 13.25 funded
FTEs per year, at a total cost of £5.22M over the 4 years of the project, plus £920k for equipment, £30k
for consumables and £120k for travel. The deliverables of the project depend on the target being
studied, but in each case we envisage significant advances over the state of the art. For comparison with
existing funding, this project has only one new staff member, a joint Fellowship with Fermilab, funded at
50% by this proposal. All the other staff have already been funded to work on target activities, though
this funding has come from a number of sources, primarily STFC, but also the European Commission
and Fermilab. This proposal, therefore, allows the consolidation of the funding of target activities within
STFC into a single project.
Contents

Executive summary ..................................................................................................................................2
1.     Introduction .......................................................................................................................................1
     1.1.    Target technologies ....................................................................................................................2
2.     Proposal for generic high power target studies ..................................................................................3
     2.1.    Work Package 1: Generic tools for high power target development and operation .....................3
     2.2.    Work Package 2: ISIS upgrades.................................................................................................4
     2.3.    Work Package 3: Thorium Energy Amplifiers .............................................................................5
     2.4.    Work Package 4: Neutrino Factory solid target ...........................................................................7
     2.5.    Work Package 5: Low energy thermal neutron production..........................................................9
     2.6.    Work Package 6: Conventional Neutrino and Super-Beams .....................................................13
     2.7.    Work Package 7: Muon to electron conversion experiments ....................................................16
     2.8.    Work Package 8: Generic fluidised powder target research .....................................................17
3.     Management ...................................................................................................................................20
     3.1.    Project Organisation .................................................................................................................20
     3.2.    Cost & Financial Management Plan .........................................................................................20
     3.3.    Schedule ..................................................................................................................................21
     3.4.    Milestones ................................................................................................................................23
     3.5.    Critical Path ..............................................................................................................................23
     3.6.    Risk analysis ............................................................................................................................23
References .............................................................................................................................................25
1. Introduction
Targets capable of reliable operation with high power particle beams, in the range 1-10 MW, are a
crucial component of many future accelerator facilities. There are many factors limiting their
performance, including the energy deposition by the beam, cooling, activation, radiation damage and
thermal shock in pulsed beams. In addition, the target systems and components must be operated,
maintained and replaced in a safe manner in an extremely challenging and intense radiation
environment. As a result, the target is the limiting factor in the performance of a number of future
facilities. Further, target and target station design, construction and operation are specialised areas and
significant improvements in performance can be achieved by the application of the appropriate
experience and skills. Due to the knowledge gained in the design of existing targets, e.g. ISIS target
stations 1 and 2 [1], radioactive ions beams [2] and the T2K target [3], and work on targets for the
Neutrino Factory [4], neutrino super-beam facilities such as the SPL to MEMPHYS [5] and LBNE [6], and
the ESS [7], the team involved in this proposal has World-leading expertise in the area of high power
targets and the skills required to make major contributions to many future projects.
Here, we propose to design and undertake R&D on a number of projects spanning a broad range
applications. These include upgrades to the ISIS target stations, contributions to the target for the ESS,
future high power neutrino super-beam and muon to electron conversion projects and targets for a
number of applications in the STFC Grand Challenge areas, including healthcare, energy and security.
We also plan to develop generic tools applicable to many high power target projects. Finally, following
the STFC Prioritisation exercise, we plan to complete work that has already been started on a Neutrino
Factory target in time for the completion of the EUROnu FP7 Design Study [8] and the International
Design Study (IDS-NF) Reference Design Report.
For convenience, the work is split into 8 Work Packages. However, although the targets to be studied
differ in detail in terms of proton beam energy, pulsed or CW operation, bunch size and the target
material, many of the issues to be dealt with are common and there are strong synergies across the
Work Packages. These synergies include:
•      Modelling the beam energy deposition in the target and the secondary particle production using
codes such as MARS, FLUKA and MCNPX;
•      Modelling of the target material response to the beam using finite element static and dynamic
codes;
•      Target cooling or replacement;
•      Activation and radiation damage in the target and target station;
•      Thermal shock;
•      Particle capture, moderation and delivery to experiments;
•      Beam windows;
•      Target station design, including shielding, remote handling, etc.;
•      Diagnostics in high radiation environments; and
•      Demanding environmental and safety requirements.
These will be treated in a uniform way across the Work Packages, so that the knowledge gained from
one can be used in another and all the expertise in the team is available for each. In addition, where
possible, the same computer codes will be used, with the associated expertise being available. The
duration of each Work Package is 4 years, except for Work Package 4 for the Neutrino Factory which is
only for 1 year. The order of the Work Packages is for organisational purposes and does not indicate any
form of prioritisation within the proposal.

                                                    1
The team making this proposal comes from four separate groups in the UK. These are from ISIS Target
stations 1 and 2, UKNF, the High Power Target Group (HPTG) from STFC Technology and a group
studying neutron spallation from Huddersfield University. Although there has already been a strong
interaction between them, bringing these groups together into a single project will strengthen these
interactions, increase the range of knowledge and skills available for each application and build a world-
leading team in high power targets.



1.1. Target technologies
The new generation of accelerator facilities requires target systems to dissipate powers in the MW
region, with pulsed energy deposition of 100s of J/g and beyond. The majority of accelerator based
facilities that require the interaction of a particle beam with a target have hitherto utilised a static solid
material for reasons of physics performance and engineering convenience. As pulsed energy densities
and integrated powers have increased, peripherally cooled static monolithic targets have given way to
subdivided, directly cooled targets with a consequent increase in heating and activation of cooling water,
or to rotating or radiatively cooled targets. Water-cooled packed beds have been successfully used as
beam dumps and helium cooled packed beds have also been proposed.
To reduce difficulties of radiation damage, thermal transport or compromises to physics performance
from the use of solid targets, contained liquid mercury has been adopted as the target technology for the
latest neutron facilities SNS and J-SNS [9] at ORNL and Tokai, respectively, and a free mercury jet is the
baseline for a Neutrino Factory (NF) and Muon Collider (MC) [10]. Liquid metal is also proposed as the
neutron production target for Accelerator Driven Sub-Critical Reactors. However, it should be noted that
there has been a recent trend away from mercury targets and that the limits of solid targets have not
been fully explored. The convenience these bring in operation means that innovative cooling or
replacement techniques should be studied before resorting to other types of target.
Fluidised powder has been suggested [11] as a technology which may have the potential to combine
some of the advantages of a solid target with those of a liquid while avoiding some of the disadvantages
of either. This may be an attractive candidate technology for targets required to operate at the highest
beam powers and power densities, e.g. for a Neutrino Factory, a Muon Collider, a Spallation Neutron
Source (possibly for an ADSR) or for a Super-Beam.
The target station is a significant cost driver for many of the facilities under consideration. In order to
make reasonable estimates of the cost of any such facility it is necessary to develop engineering
concepts for the target station, including integration and remote handling of the target and particle
capture system. This involves making compromises between instantaneous performance, mean time
between failures, maintenance and shutdown periods, and construction and running costs. Such design
decisions have a critical influence on the overall performance of a facility because after the target station
has become activated it is typically not possible to make significant changes.
In this proposal, we plan to investigate solid, liquid and fluidised powder targets, depending on the
application under consideration. The target materials we will study range from low to high atomic
number, again depending on the application. The aim in each case, however, will be to find the target
that best meets the requirements, while taking into account the practicalities of operation, maintenance,
disposal and safety.




                                                      2
2. Proposal for generic high power target studies
2.1. Work Package 1: Generic tools for high power target development and
    operation
The successful operation of high power targets relies not only on a sound target design and well
controlled operational parameters but also on having a good understanding of the real time condition of
the target at any point in its operation cycle. Target temperatures and beam position, for example, are of
key importance to this understanding as these often need to be monitored reliably and very frequently,
often over many months, during the target’s operation with beam. This is in order to give an early
warning of problems which may require a rapid intervention to correct them.
Of equal importance, but on a longer operational time scale, is a good understanding of the structural
integrity of the bulk target. For example, monitoring the potential erosion/corrosion processes which may
occur (especially at the interface between the target, its cooling medium and the containment vessel
atmosphere) is of key importance in giving operators confidence in meeting the expected lifetime of a
target and allowing timely intervention and remedial action when problems are highlighted.
In addition, with the move towards higher power densities, a thorough understanding of the thermo-
mechanical properties of the candidate target materials (especially at the extreme end of their operating
range) is vital for the target designer in order to create an optimal design.
At many facilities there is not only a requirement to improve existing target diagnostic systems (to give
more reliable data for condition monitoring) but also a need to enhance their capability to cope with new
higher power densities planned for the future upgrades of these facilities.
We plan to study a number of areas which are applicable not only to the ISIS facility targets but also to
other high power target facilities. We envisage carrying out a combination of desk top studies and test
programmes to investigate the development of reliable condition monitoring systems for the successful
operation of high power targets. The test programmes would use a combination of dedicated “offline” test
rigs and also the “online” capability offered by carrying out tests using the existing ISIS facility targets.
WP1 Tasks:
1) To investigate the maximum allowable operating temperature and allowable operating stress in high
   Z target materials.
2) To investigate the maximum allowable power density a solid target can take based on current ISIS
   beam power and beam profile and using the thermal shock test rig described in Work Package 4 and
   tests at the HiRadMat facility in CERN.
3) To identify reliable long term temperature measurement systems (circa 5 years) in a high radiation
   environment.
4) The evaluation of corrosion / erosion rates of target and target cladding materials, e.g tantalum when
   interacting with the target coolant flow; the proton beam and the target containment vessel
   atmosphere.
5) To develop a new suite of monitoring systems which allow reliable online and real time monitoring of
   the:
       a. structural integrity;
       b. coolant flow integrity;
       c. heat transfer integrity; and
       d. Erosion / corrosion resistance integrity of a high power target.
6) To identify reliable long term strain measurement systems (circa 5 years) for use in the high
   radiation target environment.




                                                     3
2.2. Work Package 2: ISIS upgrades
Until recently, ISIS was the highest power spallation neutron source in the world. Although it has now
been exceeded in beam power, it is still very competitive with the newer sources in the world in terms of
neutrons delivered to experiments. However, to remain so in the future, it will need to be upgraded both
in terms of beam power delivered to the target and the neutron flux captured and made available to
experiments.. A possible upgrade path is under investigation to take the beam power from the current
0.25MW to the few MW level. Currently, this consists of three stages (see Figure 1):




          Figure 1. A possible ISIS upgrade path. The existing facility is shown in green, the
                      3.3 GeV synchrotron in blue and the 800 MeV linac in red.

1) A new/upgraded 180 MeV linac injector into the ISIS ring. This would provide 0.5 MW to ISIS target
   station 1.
2) A new 3.3 GeV synchrotron fed from ISIS, giving 1 MW or more.
3) A new 800 MeV linac injector feeding directly into the 3.3 GeV ring, giving around 5 MW.
So far, attention has only been given to the upgrade of the accelerators in these studies. For the target, it
is planned to utilise work being done elsewhere, for example for the European Spallation Source (ESS)
in Sweden and the Spallation Neutron Source (SNS) in the US, and apply it to the ISIS upgrades at the
appropriate time. Here, we plan to study the potential implementation of these technologies with the
accelerator upgrades under investigation and look at the production, capture, moderation and transport
of the neutrons to see if improvements can be made. To do this, we will utilise the work done in Work
Package 1.
Although the details differ somewhat, for example in proton beam bunch structure, there will be a clear
synergy between the activities of this WP and that of the ESS. In addition, the ESS has recently selected
a rotating tungsten wheel for their target, though this selection is still to be approved by the whole

                                                     4
project, and we have significant experience in the use of tungsten targets for neutron production and
have studied them for use in a Neutrino Factory [4]. We plan then to collaborate with the ESS, exploiting
the contacts we already have with them and the knowledge gained from our other activities. As well as
making a significant contribution to that project, we will also gain knowledge that can be used in the
design of targets for the ISIS upgrade. There will also be a strong overlap with the ADSR activities in
Work package 3.
For ISIS, we will study the existing target station 1 to see if improvements can, in principle at least, be
made to the flux of thermal neutrons made available to the experiments before any accelerator
upgrades. In particular, we will use information gained from target station 2 to see if the moderation
system can be placed closer to the target or otherwise improved. We will also determine what the beam
power limitations are of the current technology, in particular in terms of cooling, and see if these can be
increased with small modifications. This will then determine at what stage during the proposed ISIS
upgrade path a new technology will be required. Of particular importance here is the first upgrade step,
to 0.5 MW.
For higher beam powers, we will look at the use of other target technologies, in particular from the ESS,
with the upgraded ISIS beams. We will assess how the potentially different bunch structure can be
accommodated and whether this will introduce any significant changes. For the ESS, a member of our
group has already been involved in modelling and optimising the neutron capture from the ESS target
and we have experience both in operating a tungsten target and in helium cooling, as they plan to use.
We propose to continue the modelling, contribute to work on the target and the cooling system and to
collaborate in the ESS R&D programme. We will apply the knowledge gained in these areas to an initial
design for a 5 MW target for ISIS.
WP2 Tasks:
1) Modelling of the existing TS1 at ISIS and a study of the likely beam power limit due to the beam
   energy deposition.
2) Modelling of the neutron moderation system to determine if the neutron flux delivered to the
   experiments can be increased.
3) Study modifications to the existing TS1 for operation with a 0.5 MW beam, if necessary.
4) Study the SNS and ESS target technologies and target stations and investigate their applicability for
   ISIS.
5) Participate in ESS target project by modelling their moderation system and contributions to their R&D
   project.
6) Conceptual design of a 1 MW target for ISIS.
7) Conceptual design of a 5 MW target for ISIS.



2.3. Work Package 3: Thorium Energy Amplifiers
Nuclear power is the only source of base load electricity capable of meeting future global energy
demands whilst also mitigating against risks of climate change. Unfortunately, public perception of
nuclear power is coloured by issues of safety, radiotoxic waste and links to nuclear proliferation.
Thorium-fuelled accelerator driven subcritical reactor (ADSR) technology has inherently higher safety
margins than conventional reactors, it produces less of the most difficult waste to store and it does not
produce plutonium, making it more proliferation resistant than conventional reactors. Further, there is
more thorium in the Earth’s core than uranium and all of it can be used as fuel. However, the core of an
ADSR is unable to sustain a nuclear reaction and the neutrons needed to drive the fission process must
be created via an accelerator. While this brings a significant increase in complexity, it also brings
additional safety because if the accelerator stops, so does the reactor.


                                                    5
For this application, the optimum neutron production method is via spallation [12] in a heavy atomic
number target. The detailed requirements for the accelerator and target depend on the reactor design, in
particular how close to criticality it runs. Typically, one is looking at a 1 GeV proton beam, with a beam
power in the range 4-10 MW. This would be sufficient, for example, to drive a 600 MW ADSR power
station. The demands on both the accelerator and target are far beyond the state of the art and a
number of R&D and design projects are underway. The MYRRHA project [13] in Begium is building a
sub-critical reactor with a beam power of 2.4 MW to pave the way for commercial reactors. The main
focus of this project is the transmutation of radioactive waste, rather than power generation. AKER
Solutions, which has recently been taken over by Jacobs Engineering Group [14], have announced a
design study for a full power ADSR and are seeking partners.




        Figure 2. The Jacobs” concept for beam delivery to a liquid lead spallation target in
                an ADSR. More detailed versions exist but cannot be made public.

We plan to participate in the Jacobs design study and are already in discussion with them about this.
There are a number of key areas that we propose to study, building on our existing expertise and
knowledge to be gained from the activities in Work Packages 1 and 2. The crucial issue for an ADSR is
to deliver neutrons of the right energy to the fuel in a uniform manner and to do this as safely as
possible. As a DC beam will be employed, it will also be necessary to study heat removal and radiation
damage effects. Further, it has been claimed that the target will suffer thermal shock if the beam is off for
only a short period and this is one of the issues driving the accelerator design. As this is an area of our
particular expertise, we will study this some detail. A number of target materials have been proposed for
a variety of projects, e.g. lead-bismuth eutectic for MYRRHA and molten lead for Jacobs (see Figure 2),
and we will assess these and other potential candidates for their useful neutron production and their
potential to work with the Jacobs proposed 4 MW beam. Of particular interest will be the possibility of
using thorium directly as a target and whether solids are feasible. In all interesting cases, we will study
cooling, activation, radiation damage and resulting lifetime and mounting of the target within the reactor.
We will also model the spectral effects of the neutrons on criticality and localisation of neutron production
within the reactor to obtain the optimum (and safe!) performance.



                                                     6
As the target will be located in the reactor, a beam window will be required between this and the rest of
the accelerator. With a 4 MW beam, the design of this, including its location, cooling and replacement in
case of failure, will be a critical issue. As the members of our team have significant experience in beam
window design, we will also undertake a study of this, in collaboration with those working on the beam
delivery system.
This work will be done in close collaboration with Jacobs and other partners in their design study with the
appropriate expertise in reactor design, as the integration of the target into the reactor is clearly a very
important issue. Once the design study is complete, this collaboration will put us in a strong position to
lead the implementation stage of the project, thereby gaining world-leading expertise in what could
become a crucial technology for future power generation.
WP3 Tasks:
1) Determine the parameters for Jacobs ADTR project.
2) Determine the requirements for neutron production and delivery to thorium fuel.
3) Study potential target materials to assess maximal performance in terms of neutron delivery.
4) Compare the use of liquid and solid targets, in particular studying cooling, the effect of the beam on
   the target, thermal shock, target replacement, etc
5) Study the integration of the target within the reactor and whether more than one target is feasible.
6) Produce a conceptual design of the target within the reactor.
7) Design a target beam window.



2.4. Work Package 4: Neutrino Factory solid target
The Neutrino Factory will employ a 4 MW proton beam at 5-10 GeV and approximately 0.75 MW of this
power will be deposited in the target, the rest being carried away by the remains of the proton beam and
secondary particles. The particular issue, compared to other targets being addressed, is the energy
density of the proton beam. This will be pulsed at 50 Hz, with 3 bunches per pulse. To maximize pion
production, the beam cannot be too large transversely, less than a 1-2cm in diameter, otherwise pions
are lost by re-absorption. It also cannot be too long longitudinally, otherwise muons are lost in the muon
front-end. The result is an energy density of approximately 300 J/cm3. This will create large thermal
stress in the target. The main two other issues are cooling the target and dealing with radiation damage
from the beam.
UKNF has largely focused on a solid tungsten target option for the Neutrino Factory and has made
significant progress with this. Although the baseline for the Interim Design Report (IDR) is currently a
liquid mercury jet, there is a trend in the World away from targets that are liquid, or can flow, at room
temperature for safety reasons. Interest has grown in targets which are solid are room temperature, but
with relatively low melting points, so that they can be used as liquids, for example a lead bismuth
eutectic. However, such materials are more complicated for a Neutrino Factory due the unconstrained
nature of the proposed target jet.
Due to the progress we have made, we believe solid targets are now a valid option to replace mercury in
the International Design Study Reference Design Report (RDR). Following the STFC prioritization
exercise, we plan only to complete the work that has been started with the aim of including it the RDR, in
autumn 2013.




                                                     7
     Figure 3. The measured yield strength of tungsten, with our results shown by the hashed area. The
   numbers in red are the indicative strain rates. Also shown are existing measurements from literature for
  both irradiated and un-irradiated tungsten, both at very low strain rates, with the dose for the former being
    not insignificant compared with what a Neutrino Factory target will see. These measurements finish at
              o
        1000 C, but we have extrapolated them to higher temperatures. The crosses are our lifetime
   measurements for use in a Neutrino Factory, given in million pulses. They should be multiplied by 10 to
                  turn them into target lifetimes in millions of seconds, with 500 target bars.

In UKNF, we have demonstrated that targets using tungsten have a sufficient lifetime for use in a
Neutrino Factory [15] at the temperatures required, but only using very small samples. As the strength of
the material depends on its size, both through the strain rate of an applied shock [16] and the method by
which it is manufactured, we must extend this work to bulk samples to demonstrate that there are no
significant changes. For this, we will employ a high energy density beam at CERN, HiRadMat [17], as
that is the only way to create a sufficient energy density. We will also endeavor to verify that the strength
is not significantly degraded by radiation damage from the beam by testing existing targets with varying
levels of damage from ISOLDE. In addition, as the energy deposition by the beam in the target is very
large, approximately 0.75 MW, it is necessary to change the target between beam pulses to avoid the
target getting too hot. With the help of engineers from ISIS, we have designed a chain built entirely from
tungsten to do this. A scale model has been built in stainless steel and initial tests of this have shown no
inherent problems with the design. Here, we plan to manufacture and test a model of a chain using
tungsten and to test this, initially at room temperature, but later at the higher temperatures that will exist
in a Neutrino Factory. This chain will be tested for extensive periods to study its operation and any wear

                                                          8
encountered. We also plan to check the effect of radiation on both the links in the chain and tungsten
disulphide that we plan to use as a coating. This will be done with the HiRadMat facility. The result will
be an engineering demonstration of a solid target able to work in a Neutrino Factory. In addition, we will
continue to model particle production to determine the shielding requirements in the target station and to
aid the efforts to reduce the heat load in the superconducting capture solenoids.
Using the purpose-built facility for determining the lifetime of solid targets, we have also measured the
Young’s modulus and the yield strength of tungsten and tantalum at high temperatures and high strain
rates (see figure 3). These results are unique and have now been published [4, 18] and have created
significant interest in the appropriate fields in materials science. Further, requests have been received to
make measurements of other materials for other projects and the possibility of providing these
measurements commercially is under investigation.
WP4 Tasks:
1) Determine the yield strength of bulk samples of tungsten using the HiRadMat facility at CERN.
2) Check if the yield strength is adversely affected by radiation.
3) Construct and test a model of a tungsten chain.
4) Continue particle production and heat load simulations to aid in the target station design.


2.5. Work Package 5: Low energy thermal neutron production
In this work package we propose to study the production of intense beams of thermal neutrons using
compact, low energy and low cost accelerators with the aim of providing compact and relatively cheap
facilities. We will investigate three applications, each of which is in one of the STFC global research
challenge areas. They are:
   Boron Neutron Capture Therapy (BNCT), a type of radiotherapy for treating aggressive tumours that
    infiltrate the surrounding tissues and are particularly difficult to treat by other means;
   The production of molybdenum 99, which is used to produce technetium-99m, a short-lived gamma
    ray emitter which is one of the most commonly used radioisotopes in medical imaging; and
   Security applications, in particular the screening of cargo containers for shielded nuclear material.
These are grouped into a single work package as each will focus on neutron production via the Li(p,n)
reaction, as this has the biggest cross-section at low energy (see Figure 4).


BNCT
Tumours in which the cancerous cells infiltrate the surrounding healthy tissue are particularly difficult to
treat for two reasons. Firstly, there is no clear boundary to the tumour, making it difficult to image and to
be sure the whole tumour is being treated. Secondly, it is difficult to treat the entire tumour using surgery
or radiotherapy without significant damage to healthy cells. An example of such a type of cancer is a
glio-blastoma multiforme (GBM), the most common form of primary, malignant brain tumour. Currently,
the most advanced treatment for this is a combination of radiotherapy and a drug called Temozolomide
[19]. Recent trials have shown that this increases the 2 year survival rate to 26.5%, compared to 10.4%
with radiotherapy alone.
Boron Neutron Capture Therapy (BNCT) is a form of binary cancer therapy that looks particularly well-
suited to treating this type of tumour. The first of the two components in the therapy is boron-10, which is
bound to a carrier compound, either 1-p-borono-phenyl alanine (BPA) or borocaptate sodium (BSH),
which is preferentially absorbed by active tumours. The tumour is then exposed to the second part of the
therapy, thermal neutrons, resulting in the following reaction:
                                      1
                                          n10B4 He 7Li  2.8MeV

                                                     9
The ions produced destroy the cancerous cell in which they are created. The cross-section for this
reaction is several orders of magnitude bigger than the neutron absorption cross-sections of any of the
other elements commonly found in tissue. The result of this is shown in Figure 5. This indicates that
although the ratio between the total dose to cancerous and normal tissue varies as a function of depth, it
is at worst a factor of 2 and at best a factor of almost 6 for treating GBM.




            Figure 4. Neutron yields from a variety of reactions using low energy beams.
Recent trials, in which BNCT is combined with X-ray radiotherapy, have shown promising results.
Studies in Japan in 2009 have measured a median survival time of 25.7 months and a 2 year survival
rate of 45.7% [20]. Work done in Birmingham University in the UK shows that this combined dose is
necessary because not all cancer cells, only between 60 and 90%, actually take-up BPA and the X-ray
dose is required to treat the remainder [21]. It is for this reason that earlier studies of BNCT showed little
apparent benefit from the therapy. This work has also led to the development of a model which will
provide a framework to combine BNCT and X-ray radiotherapy on a case-by-case basis to achieve the
optimal outcome. As well as GBM, BNCT may also be applicable to other, more common, types of
difficult to treat cancer, including lung, head and neck and metastatic liver cancer. The challenge with
BNCT is it requires a large flux of thermal neutrons, around 109cm-2s-1 for a 20 to 30 minute treatment,
and such a flux is currently only available from a nuclear reactor. It is possible to create this using an
accelerator, but typically, one requires about 5 mA of protons at around 3 MeV, corresponding to 15 kW
of beam power. Due to the low energy, the preferred targets are lithium and beryllium, with the former
being more frequently studied as the production is bigger at lower proton energy. In both cases,
however, the proton beam penetrates only a short distance into the target and this power is deposited in
a very thin layer. So far, nobody has managed to create a target able to work in these conditions. As a
result, only an extremely small number of patients, approximately 600, have been treated by BNCT, all
using nuclear reactors. No randomised clinical trials of the therapy have taken place.
We plan to investigate lithium targets. The options for target construction are very limited as the melting
point of lithium is only 180oC. One possibility is to use a (flowing) liquid target, which has the advantage
of carrying the heat deposited in the target away. A number of such targets are being studied, but they
have significant health and safety issues for a use with patients in a clinical environment. As a result, the
preference is for a solid target and we plan to focus mainly on one design, invented in Birmingham [22].
                                                     10
This uses a 0.7 mm thick lithium layer firmly bonded to a copper backing and is currently the only solid
option demonstrated to work to the 1-2mA level. To go to 5mA, we need to increase the capacity of the
target cooling system over that currently used. Due to the latent heat of melting of the ice, binary ice [23]
has demonstrated a factor of up to 8 increase in cooling capacity compared to water in existing
applications. If this can be replicated with a BNCT target, it would be sufficient for our needs and some
preliminary modelling with Fluent suggests that this should be achievable.




              Figure 5. BNCT doses to a tumour and normal tissue using a phantom in
                                  Birmingham University [20].
To determine whether it will meet our needs, a proof-of-principle experiment is planned and has recently
been funded by STFC. This will use existing binary ice machines provided by a colleague from Denmark
to test a mock-up of the Birmingham BNCT target station. If binary ice looks like it will be successful, we
will then buy, install and test a machine on the existing Birmingham facility. We will also re-visit the
neutron production to ensure the maximum dose can be delivered to GBM tumours in a patient and
optimise beam delivery to the target. These developments will allow phase I and II clinical trials of BNCT
to be undertaken.
The next stage of the project is then to develop a compact facility. The existing Dynamitron accelerator in
Birmingham is very old and not terribly compact. However, Siemens are building a very compact
electrostatic accelerator [24] that would be ideal for this application. In particular, the ion source,
accelerator and target would be small enough to fit into the footprint of an existing standard radiotherapy
bunker. The first Siemens machine is to be built at the STFC Rutherford Appleton Laboratory and this
machine may be available for use in Birmingham after tests. As the geometry with this accelerator will be
quite different, we will design a new target station for this accelerator, based on what is learnt in
Birmingham. We will then endeavour to build and test this target station either at RAL or in Birmingham.
WP5 Tasks for BNCT:
1) Determine requirements for binary ice machine for Birmingham.
2) Modify Birmingham target station and add binary ice, if sufficient cooling power can be achieved.
3) Test and, if funding is available from other sources for clinical trials, participate in these at the
   required level.
4) Optimise the target geometry for epithermal neutron production using the Siemens’s accelerator.
5) If the equipment from Birmingham can be re-used, construct and test a target station for the
   Siemens’s accelerator.

                                                     11
Molybdenum 99
Molybdenum 99 (Mo99) is used for the production of technetium-99m, which is a nuclear-isomer of
technetium-99. Technetium-99m undergoes a transition to technetium-99 with a half-life of 6 hours,
emitting a readily detectable 140 keV gamma ray. This makes it ideal as a radioactive tracer in medicine
and it is the most commonly used isotope for this, being used in around 85% of all cases. Molybdenum
99 is in turn produced by bombarding uranium 235 with high intensity neutrons, the molybdenum being
produced by the fission of the uranium. This is currently done in five reactors around the world, all of
which are old. Two have recently had to be closed down due to coolant problems, though one is now
working again. This created a shortage of molybdenum 99 and, due to the age of these reactors,
concern persists about possible shortages in the future. The Department of Health has identified the
supply of Mo99 has a critical issue and is encouraging the study of alternative production methods [25].
As for BNCT, it is possible to produce Mo99 using neutrons generated by an accelerator. However, the
requirements are very demanding for this method to be economically competitive with a reactor as the
optimal neutron flux is about 1014cm-2s-1. This means the accelerator must have a very high particle
current, the neutron production cross-section has to be very large and the whole complex relatively
cheap, as it is possible that more than one accelerator will be required. The most promising reactions to
use are shown in Figure 4, taken from [26]. The detailed requirements will require modeling of the
neutron production, moderation and transport, but it is already clear that a beam current up to or
exceeding 100 mA will be required. This is a challenge for both the accelerator and the target, though
options are already under study for the former [27]. As the beam power could reach 500 kW, the main
issues will be heat removal and activation. For this reason, two reactions from the figure are of particular
interest: Li(p,n) and D(d,n). For the former, a liquid lithium target would be used, while for the latter it
would be a heavy water target. In both cases, the heat could possibly be carried away using a flowing
target and this would also increase the volume of target over which the activation is spread. For safety
reasons, lithium is again preferred as it is solid at room temperature.
In this project, we plan to undertake detailed simulations of the neutron production and heat deposition in
a liquid lithium target, do a conceptual design of the moderation and reflection system to deliver the
neutrons to uranium 235 samples and of the Mo99 collection system, based on existing designs. We will
determine the beam requirements to deliver an economically competitive system. If practical, we will
then design a target for a liquid lithium target and test this out using one of two possible low energy
proton facilities at RAL: the Front End Test Stand (FETS) [28] or the new accelerator to be installed and
tested by Siemens. Although neither of these will achieve the required current, they will at least allow the
target to be tested with a proton beam of the current energy.
WP5 Tasks for Mo99:
1) Modelling of neutron production and heat deposition within the liquid lithium target.
2) Study of heat transfer within the lithium and possible cooling mechanisms.
3) Requirements for a liquid lithium target and comparison with existing targets.
4) Study of neutron capture and delivery to the uranium.
5) Extraction of Mo99 and the resulting rate of production.
6) Comparison with other production mechanisms.
7) Conceptual design of a Mo99 production target station.


Security Applications
Of particular interest in this area is the screening of cargo containers transported across borders either
by truck, train or ship for shielded nuclear materials. These are otherwise difficult to detect quickly by
other means. The requirements are challenging as 90% of the world’s trade moves via sea-going
containers. As these tend to arrive in ports in bulk on large container ships, they need to be scanned

                                                    12
quickly, in less than 1 minute per container. The containers themselves are large: around 2.6m by 2.6m
in transverse dimensions and up to 12m long and the material they contain is diverse. The successful
delivery of one consignment of nuclear material could be catastrophic, nevertheless the false positive
rate must be kept very low to avoid significant disruption to trade. As a result, a number of techniques for
detecting this material are under study or already in use.
One of those under study is the active scanning of containers using neutrons, which result in prompt
photon production when interacting with uranium-235 or plutonium-239. These characteristic photons
can then detected by using detectors surrounding the container, though discriminating a signal from the
background can be very difficult. Due to the variable nature of the material potentially surrounding the
nuclear material to be detected, an intense neutron beam is required with a range of energies up to a
limit of 10 MeV, at which point the activation of oxygen becomes important.
Here, we plan to undertake a simulation study to determine in detail what the requirements are for the
neutron beam and whether either of the two projects described above would bring improved
performance or lower cost than the other studies taking place and hence could also be developed in this
direction.
WP5 Tasks for Security:
1) Determine beam requirements for the scanning system.
2) Review projects already underway.
3) Determine performance of a system based on either the solid or liquid lithium option described
   above, depending on the requirements.
4) Compare the potential performance with the existing projects.


2.6. Work Package 6: Conventional Neutrino and Super-Beams
So-called ‘conventional’ neutrino beams are generated as a tertiary beam from the decay of secondary
pions that have been produced by the interaction of a proton beam with a low-Z target. A magnetic horn
system is used to capture and focus a single sign of pions. All existing accelerator-driven neutrino
facilities use this technique. T2K is the latest [29], beginning operation in 2010 and currently recovering
from the recent earthquake having apparently been spared serious damage. In collaboration with
Japanese physicists, the RAL High Power Targets Group was responsible for delivering the T2K target
system for operation at up to 0.75 MW. This will push the pulsed power limits of what can be achieved
with a monolithic graphite target [3]. A photograph of the installation of the T2K target into the 1st
magnetic horn using remote handling equipment is shown in Figure 6.




                   Figure 6. Installation of T2K target into 1st magnetic horn.


                                                    13
Scientists in Europe, the US and Japan are actively pursuing the extension of this conventional
technique to primary proton beam powers of over 1 MW. Such a ‘Super-Beam’ is likely to be the next
neutrino facility to be developed, for which the target system is widely acknowledged to be the limiting
technology. There are many similarities in target requirements for the various plans, in particular the
design, analysis and manufacturing techniques, also in materials testing and diagnostics. However,
differences in beam parameters and existing infrastructure mean that the optimal target technology
choice may be different e.g. for the 0.7 - 2 MW LBNE facility at FNAL, the T2K road map to 1.66 MW and
the proposed 2 MW LAGUNA LBNO facility at CERN. After the success of the T2K project, the UK group
responsible for the target has been invited to play a key role in the design and analysis of target systems
for these projects. This work package comprises a multi-strand Super-Beam target development
programme, making maximum use of previous experience and synergies in techniques and technologies
for the different projects. This will involve the consideration of various technologies and their relative
advantages, disadvantages and limits, with prototyping of critical processes. Simulations will be
benchmarked by carrying out off-line heat transfer experiments. These experiments would utilise and
upgrade the roots blower circuit already constructed for WP8 by incorporating an induction heater and
diagnostics equipment. On-line material damage experiments will be specified and followed up if
opportunities arise. This work will enable the selection of the optimum technology for the first neutrino
Super-Beam to be developed.
Most of the facilities in this proposal require a beam window to separate the accelerator vacuum from the
target station, which is typically at atmospheric pressure. Also, many target designs rely on a window to
contain the coolant. A study will be included in this work package to identify beam window candidate
materials and optimise the design and geometry to minimise static and dynamic stresses and
temperatures for the different Super-Beam facilities. This study may also be extended to other facilities in
the proposal.


T2K road map to 1.66 MW
Although the recent earthquake has interrupted the intensity progression of the T2K facility, when it is
operational again the beam can be expected to increase in intensity from 150 kW towards the target and
beam window design beam power of 750 kW, and to follow the 5 year ‘road map’ to 1.66 MW. The T2K
international collaboration anticipates the RAL High Power Targets Group to retain its current
responsibility for the target and associated systems, and to develop new concepts for operation at higher
beam powers. This forms the first strand of the Super-Beams work package.


Long Baseline Neutrino Experiment (LBNE) at FNAL
In 2010 the RAL HPTG completed a conceptual design study of target components for the Long
Baseline Neutrino Experiment (LBNE), carried out by 3 staff-years of effort funded by Fermilab. The
study considered a beam energy of 60 GeV or 120 GeV for operation at both 0.7 and 2 MW. The higher
power option would utilize the Project X beam, construction of which is a high priority for Fermilab after
the Tevatron ceases operation. The study investigated a number of different concepts using beryllium as
a potential target material as an alternative to the baseline graphite. The resulting report made a number
of technology recommendations which will be used as input to a forthcoming US DoE CD-1 review.
Figure 7 shows one plot from this study, the Lorentz stresses in a combined target and horn inner
conductor at the peak of the horn current pulse.
LBNE management at Fermilab have indicated a strong interest in the RAL group taking this work
forward over the following 3-4 years. This provides the second motivation for this work package.



                                                    14
    Figure 7. Lorentz stresses in a combined target and horn inner conductor at peak of
                                       current pulse.


LAGUNA Long Baseline Neutrino Observatory (LBNO) neutrino programme at CERN
The FP7 funded EUROnu project to study the technical challenges and compare the physics
performance of Superbeams, Beta Beams and Neutrino Factories will be completed in 2012. The target
research component of this study is included in the Super-Beam work package, with the objective to
produce a Conceptual Design Report for a Super-Beam using a proposed 4 MW 5 GeV Superconducting
Proton Linac (SPL) at CERN . This work is being carried out by the RAL HPTG working in collaboration
with CEA at Saclay, IN2P3 at Strasbourg and the Cracow University of Technology. Figure 8 shows
velocity vectors in a computational fluid dynamics model of a concept for a helium cooled packed bed.
Following on from EUROnu, the LAGUNA-LBNO proposal for a CERN neutrino programme was
favourably reviewed by the EC in April 2011 and is expected to begin in September 2011. A modest
(0.25 SY) contribution to the RAL HPTG has been included to ‘[develop] a basic conceptual design of the




           Figure 8. Velocity contours on a section of a CFD model of a packed bed target.
target and focusing region […], using expertise obtained in the design of a similar system for a graphite
target for the T2K (Japan) project and in studies for a beryllium target for the LBNE (FNAL) project.’ The
proposal is for a 2 MW beam which could operate at 3-5 GeV, 50 GeV or 400 GeV. Support for this work
will form the final thread of this generic Super-Beams work package.
WP6 Tasks (inclusive of all facilities under consideration):
1) FLUKA and ANSYS simulations of candidate target and beam window materials.
2) Specification of preferred candidate materials for target and beam windows over range of required
   operating conditions. Specification of material irradiation tests and off-line shock fatigue tests
   required to estimate material lifetimes.


                                                   15
3) Beam window design and specifications.
4) Determine operating limits of helium cooled graphite targets and develop detailed designs.
5) Explore potential of air, helium and water cooled beryllium targets.
   a) Develop detailed design of at least one beryllium target.
6) Develop detailed design of packed bed target of either Ti or Be spheres.
   a) Target windows and container design.
7) Specification of preferred target technology for each facility.
8) Prepare generic conceptual design of Super-Beam Target Station.
   a) Outline design of target integration with horn including Remote Maintenance concepts.
9)   Off-line heating and cooling tests: inductively heated and helium cooled pebble bed target.


2.7. Work Package 7: Muon to electron conversion experiments
Both Mu2e in the US and COMET in Japan are experiments being designed to search for the coherent
conversion of a muon to an electron within the field of a nucleus, the signature of which is a mono-
energetic 105 MeV electron. This would be an example of charged lepton flavour violation, which has
never been observed. Both experiments require a target station that shares similarities with a NF/MC
target station, namely a high Z target within the bore of a solenoid to maximize the production and
capture of low energy pions. The solenoid is axially graded to capture and focus pions in the reverse
direction. A curved transport solenoid selects a single sign of low energy muons which are captured in
the nucleus of an aluminium target. These experiments are aiming to be more sensitive to charged
lepton flavour violation by four orders of magnitude compared to the previous measurement. COMET is
the first phase of the COMET/PRISM programme, with PRISM being an FFAG accelerator-based
experiment making use of a pulsed proton beam of power 2 MW or more, which improves the sensitivity
by two further orders of magnitude, which would allow precise measurements of the muon-to-electron-
conversion process across many different types of nuclei. The purpose of the work package is to
maximise impact by developing common areas and thus position the UK to exploit opportunities as they
arise.


Mu2e
The baseline Mu2e pion production target is a water cooled thin gold rod. A collaboration between RAL
staff from the HPTG, the Project Engineering Group and ISIS is currently carrying out a conceptual
design study of the Mu2e experiment target, components and systems. This is required to produce a
conceptual design at the 10% level for an imminent CD-1 review by the US Department of Energy.
Fermilab is currently funding this work at a level of 2-3 SY.
A pre-CD-1 Director’s review on May 3rd 2011 stated: ‘We commend the project for securing extra
engineering help, particularly the High Power Target expertise of the RAL group. Significant progress
has been made towards the conceptual design, but significant work still remains to be done. Going
forward, the project should continue with plans to utilize the resources of RAL engineer’s through the
preliminary and final design.’ This study will be completed by September 2011, and to take the work
forward as requested by Fermilab would require funding of the UK group.


COMET
COMET is being proposed at the J-PARC proton accelerator laboratory in Japan, where UK groups
including RAL have much experience working through our contributions on the T2K neutrino oscillation
experiment. COMET will take the same proton beam, running at 8 GeV and 56 kW, slow-extracted to


                                                   16
approximately 106 bunches over two seconds. The current design calls for a water-cooled tungsten rod,
however the collaboration recognises the need for optimisation in terms of both the target material and
cooling methods. The COMET collaboration have constructed, as a prototype R&D project, the world's
first superconducting pion capture solenoid which is being operated in the proton beam the RCNP
laboratory in Osaka. Other related R&D projects include irradiation studies at the Kyoto University
Research Reactor of the aluminium stabiliser for the superconducting coils that are used across the
experiment. UK university groups at Imperial College and UCL have been heavily involved in the
conceptual design process for COMET and are seeking funding to strengthen UK participation in this
project.
WP7 Tasks:
1) Develop conceptual design of muon production target including optimum material selection and
   cooling method.
2) Final design of production target.
3) Design of production target support and integration system within solenoid.
4) Design of target handling, replacement and disposal system.
5) Beam window/end cap design.
6) Conceptual design of Target Station.
7) Prototyping of target manufacture.
8) Prototyping of target support and integration system.


2.8. Work Package 8: Generic fluidised powder target research
A research programme supported by ASTeC is being carried out by the HPTG at RAL to study the
practical implementation of fluidised, flowing powder as a new high power target technology. The
motivation is to investigate whether such a technology can combine some of the advantages of a solid
target with those of a liquid while avoiding some of the disadvantages of either. To date, the research
has studied the fluidisation of tungsten powder using air or helium as the carrier gas. The powder flows
within a horizontal pipe opening out into a free jet, after which it is re-circulated using a vacuum lift. This
configuration may be suitable for a Neutrino Factory, a Muon Collider or a Spallation Neutron Source
e.g. for an ADSR. It is intended to extend this research to the use of a low-Z material powder which may
be more appropriate for application to a Super-Beam.
Numerical simulations are not generally useful in the study of the behaviour of bulk powders, and so the
research programme is necessarily predominantly experimental. Fortunately, many of the questions
relating to the implementation of a flowing powder target can be investigated experimentally and,
crucially, off-line. Also, unlike mercury, powdered tungsten is non toxic. These factors mean that a highly
productive experimental programme can be undertaken at a relatively modest cost. To this end, a test rig
has been constructed and commissioned at RAL that will be used to further the research programme.
The test rig has so far demonstrated that tungsten powder can be readily conveyed both as a continuous
dense phase flow within a partially filled pipe and as a stable and coherent open jet. Material fractions
approaching the static bulk powder material fraction of 42±5% have been achieved, at flow velocities of
around 4 m/s and a mass flow rate of around 8 kg/s in a 2 cm diameter pipe. So far it has been possible
to recirculate powder in the lean phase at up to 2.5 kg/s by a 4 m vertical vacuum lift. Figure 9 shows an
example of unstable flow within a glass pipe.
This work package seeks to exploit the previous investment in this area and develop the rig into an
increasingly realistic prototype of a target system. The first objective is to achieve a full pipe ie solid
dense phase flow, then optimise the recirculation system to enable an upgrade to CW operation. A
significant piece of work is then required to carry out experiments on erosion and its mitigation to enable

                                                      17
medium term CW operation, although it is not anticipated to be able to develop the current rig to the level
of long term running tests.
A proton beam interacting with a contained fluidised target system would generate significant secondary
heating in the pipe wall. This may be mitigated to some extent by heat transfer to the flowing powder.
With medium term CW operation of the rig, heat transfer experiments are planned to measure this effect.
This would use the same power supplies and upgrade to the roots blower circuit required for the packed
bed studies of WP6, and so there would be further sharing of equipment costs between the two work
packages.




       Figure 9. Discontinuous dense phase flow of tungsten powder within a glass pipe.

An application for an on-line test of a tungsten powder sample with a few high intensity beam pulses has
been accepted to run on the HiRadMat facility, currently under construction at CERN. The purpose of the
experiment is to investigate whether rapid expansion of the carrier gas could cause damage to the wall
of a contained powder or deterioration of an open jet. This will be one of the first experiments to operate,
with a tentative experiment date of autumn 2011. A CERN research student has been recruited to carry
out the experiment in collaboration with RAL staff.
A more complete experiment is included in this proposal to observe any effects of powder interaction
with the pipe wall via rapid expansion. This would use a Laser Doppler Vibrometer to distinguish
between the powder and secondary particle interactions with the pipe wall.
It has been suggested that the strong magnetic fields e.g. from a solenoid or magnetic horn in a neutrino
facility may cause charged powder grains to be captured and focused, causing damage to any
downstream beam window. It is planned to test the effects of ‘static’ charge offline using a suitable high
field magnet, and if possible to measure the effects of proton beam interactions on-line at the HiRadMat
facility in a third experiment on this facility.
WP8 Tasks:
1) Flow rig development for tungsten powder
   a) Flow optimization to achieve solid dense phase flow (ie full pipe flow), and investigation of low-
       flow limit.
   b) Gas lift and recirculation optimization.
   c) Upgrade to CW operation.
   d) Erosion tests and development of mitigation techniques.
2) Heating and cooling tests of heat transfer between powder and pipe wall. Develop concept for pipe
   wall and cooling in e.g. Neutrino Factory scenario.
3) Develop suitable diagnostics for monitoring and control.
4) Pulsed proton beam test at HiRadMat facility, CERN, using Laser Doppler Vibrometer to measure
   stress waves generated in powder container.
5) Off-line investigation of magnetic field effects on fluidized powder.
6) In-beam investigation of magnetic field effects on fluidized powder at HiRadMat facility, CERN.

                                                    18
7) Identify suitable low Z powder and repeat of 1-6 above.
8) Outline circuit design including active powder handling issues.
9) Conceptual design of Target Station.




                                                   19
3. Management
3.1. Project Organisation
The management structure for this project will consist of the following bodies:
Executive Board (EB): This will be responsible for the day-to-day running and financial management of
the project. It will ensure that the project milestones are being met, monitor the expenditure and make
any corrections that are necessary. The EB will consist of the PI (Rob Edgecock (STFC)) and the deputy
PI (Chris Densham (STFC)) and the Work Package (WP) managers. It will meet on a monthly basis.
Steering Group (SG): Although this is now a separate proposal, many of the activities being undertaken
originate in UKNF or have close connections to the other Accelerator R&D proposals. As a result, it is
planned have a body, the Steering Group, which will oversee the four proposed projects. This will be
chaired by Ken Long (Imperial) and for this project, the representatives will be the PI and deputy PI. The
SG will meet about twice per year, will receive reports from each project and advise on progress and
possible problems.
Work Packages (WP): The project consists of the 8 Work Packages described in Section 2. Each of
these is assigned a Work Package Manager (WPM). The current list of these is shown in Table 1. The
WPM will be responsible for the day-to-day running and financial management of the WP and will report
on progress against milestones, deviations from the expected expenditure profile and problems to the
EB.
                         Table 1: Work Packages and Work Package Managers
    Work                                   Description                                   Manager
   package
       1         Generic tools for high power target development and              David Jenkins (STFC)
                 operation
       2         ISIS upgrades                                                     Matt Fletcher (STFC)
       3         Thorium energy amplifiers                                        Rob Edgecock (STFC)
       4         Neutrino Factory solid target                                         Goran Skoro
                                                                                        (Sheffield)
       5         Low energy thermal neutron production                            Rob Edgecock (STFC)
       6         Conventional neutrino superbeams                                 Chris Densham (STFC)
       7         Muon to electron conversion experiments                          Chris Densham (STFC)
       8         Generic fluidised powder target research                         Chris Densham (STFC)
Project meetings: In addition to the meetings already discussed, it is planned to hold general meetings
of the four accelerator R&D projects being proposed twice per year, if approved, so that each project
maintains a close collaboration with the others. This high power target project will hold meetings of all
participants a further two times per year. The individual WPs will meet regularly, at least once every two
months.

3.2. Cost & Financial Management Plan
The full costs for the project, separated into Work Packages are shown in Annexes A and B. They are
also summarised in Je-S.


                                                    20
The financial management of the project will take place as follows. Each WP will be assigned a separate
ASTeC project number within the Shared Services Centre. It will be a main responsibility of the WPM
manager to monitor the actual expenditure on this project number against expectation. The ASTeC
financial team will provide tables of the expenditure on a monthly basis. These will be sent to the PI and
each of the WPMs and the latter will then report on this to the SC. The SC will ensure that action is taken
to fix any significant deviations from the expected spend profile.
Approval will be required for all travel and hardware expenditure. Travel with a total cost of less than
£1000 will need to be approved by the corresponding WPM. Costs above this limit must be referred to
the PI by the WPM. Hardware costs of less than £5000 can be approved by the WPM. Costs above this
will need to be approved by the EB.

3.3. Schedule
The project is scheduled to last for 4 years. All of the WPs will continue for this duration, except for WP4,
the Neutrino Factory solid target. As UKNF is in a managed withdrawal phase, we plan only to finish off
the work already started and complete this in time for the International Design Study Reference Design
Report due in 2013. As a result, this WP is scheduled only for the first year of the project.
As described above, a number of tasks have been defined for each WP and these have been used to
create milestones. The schedule for the project has been defined in terms of these milestones and is
shown in a Gantt chart in Figure 10.




                                                     21
Figure 3.1: Schedule for the Project




    Figure 10. Gantt chart




                22
3.4. Milestones
As described in Section 3.3, the milestones for the project have been created from the tasks defined for
each WP. As this is an R&D project, these tend to be more detailed at the start and become more
general as the project develops. The milestones are shown in for each WP in Annex 2 and are
summarised in the Gantt chart of Figure 10.

3.5. Critical Path
This project consists of a number of R&D programmes on targets at or beyond the frontiers of current
knowledge. The main aim is to identify and test possible routes forward, rather than delivering working
target stations at this stage. As all the work being done is R&D, by its very nature there is potential for
slippage in the milestones and it is not possible at this stage to identify what will be the critical path item
for each WP. Instead, in section 3.6 and Table 2, we have identified the main technical risks for the
project. Each of these could result in a delay in the work or its termination. The EB will monitor progress
against the milestones and take remedial action if this is required.

3.6. Risk analysis
Technical risk: An analysis of the main technical risks for each of the WPs is given in Table 2.
                                      Table 2: Project Technical Risks
WP             Description              Likelihood     Impact     Risk                Mitigation
                                           (0-5)        (0-5)
 1    Not possible to identify               1             2        2     Secondary methods, such as
      reliable, long term target                                          cooling water temperature, are
      temperature measurement                                             currently employed and can still be
      devices                                                             used.
 1    Not possible to develop                2             2        4     Develop and implement the
      complete set of systems for                                         systems that can be developed.
      the online monitoring of
      targets
 1    Not possible to identify long          2             2        4     Develop systems for shorter term
      term strain rate systems for                                        measurements, but ensure these
      high radiation environment.                                         can be replaced after failure.
 2    Existing ISIS target cannot            2             3        6     More significant changes required
      be easily modified to 0.5MW.                                        to achieve 0.5 MW.
 2    1 MW ISIS target not                   1             4        4     Determine maximum possible
      possible.                                                           beam power.
 2    5 MW ISIS target not                   3             3        9     Determine maximum possible
      possible.                                                           beam power.
 3    Not possible to design beam            2             4        8     Determine what the maximum
      window for 4 MW beam in an                                          useable beam power is.
      ADSR.
 3    Not possible to implement 4            2             4        8     Determine the maximum possible
      MW target within an ADSR.                                           beam power.

                                                      23
 4   Not possible to test tungsten         1            3        3    Verification of bulk tungsten not
     in HiRadMat facility                                             possible for a Neutrino Factory
 4   Yield strength of bulk                2            3        6    Use alternative target technology
     tungsten not large enough.                                       for Neutrino Factory.
 4   Irradiated tungsten too brittle       2            3        6    Use alternative target technology
 4   Tungsten chain shown not to           2            3        6    Use alternative target technology
     be feasible
 4   Target station shown not too          2            5       10    Reduce beam power, capture
     be feasible with baseline                                        solenoid magnetic field, etc, until
     parameters                                                       feasible.
 5   BNCT: binary ice cannot               2            5       10    Study alternative target layouts.
     provide sufficient cooling.
 5   BNCT: funding not available           2            4        8    Demonstrate target feasibility and
     for clinical trials                                              collaborate with overseas
                                                                      colleagues on clinical trials.
 5   BNCT: Siemens accelerator             3            3        9    Collaborate with IBA instead.
     does not work
 5   Moly99: beam current                  3            4       12    Study beryllium and other neutron
     achievable with liquid lithium                                   production reactions.
     target too small
 5   Moly99: Mo99 extraction               2            5       10    Determine what is achievable for
     efficiency too small                                             comparison with other
                                                                      possibilities.
 5   Security: Proposed                    1            5        5    Stop studies.
     production methods cannot
     meet requirements
 5   Security: Proposed methods            2            5       10    Stop studies.
     not competitive
 6   Proposed target technologies          2            4        8    Study more complex target types.
     unable to meet requirements
 7   Proposed targets incapable            2            4        8    Investigate other target options.
     of delivering physics goals
 8   Show-stopper found for                2            5       10    Stop studies.
     powder jet target


Financial risk: A number of the targets being studied in this project are in the early stages of
development. Nevertheless, hardware will need to be purchased during the project to complete the work.
There is, therefore, a risk related to the cost of this hardware. In all cases, the costs included are the
best estimate of what will be required, but as this is an R&D programme, there are significant
uncertainties. The biggest sources of risk are:



                                                   24
   WP1: An estimate has been made of the cost of the instrumentation and the testing that will be
    required. However, until the work starts, there is an uncertainty on what may meet the requirements
    and hence how much it will cost.
   WP4: The biggest hardware cost in this work package is the model tungsten chain. The
    manufacturing technique for this still has to be identified and hence there is an uncertainty on the
    cost of this manufacture.
   WP5: The biggest cost for this WP is the binary ice cooling machine for BNCT. Until the proof-of-
    principle experiments are finished, it is uncertain whether this technique will work and what the
    required cooling power will be, though modelling suggests it will work. The cost of the biggest binary
    ice machine has been included. It is likely that a smaller machine will be required and this cost will be
    less in reality.
   WP6: The hardware costs for this WP are to build and test, both offline and online, target options for
    Superbeam projects. The options to be tested and the scope of the tests depend on the outcome of
    the design work done beforehand. This leads to an uncertainty in the costs of these tests.
   WP8: The hardware costs are for the upgrade of the powder test rig. These upgrades will not be
    required if early tests find significant problems with the technology itself.

References
[1] D.J.S. Findlay, Operational experience with high beam powers at ISIS, in Proc. 42nd ICFA Advanced
        Beam Dynamics Workshop on High-Intensity, High-Brightness Hadron Beams (HB2008),
        Nashville, Tennessee, USA, 25-29 Aug 2008.
[2] J.R.J. Bennett et al, Nuclear Instruments and Methods in Phys. Res. B 126 (1997) pp 105-112.
[3] T. Nakadaira et al, T2K Target, AIP Conf. Proc.: 981 (2008), pp. 290-292.
[4] J.R.J. Bennett et al, Lifetime and strength tests of tantalum and tungsten under thermal shock for a
        Neutrino Factory target, Nuclear Instruments and Methods in Phys. Res. A 646 (2011) pp 1-6.
[5] J.E. Campagne et al, Physics potential of the CERN-MEMPHYS neutrino oscillation project, J. High
         Energy Phys. 04 (2007) 003.
[6] P. Hurh et al, High Power Target R&D for the LBNE Beamline: Status and Future Plans, in Proc. 43rd
        ICFA Advanced Beam Dynamics Workshop on High-Intensity, High-Brightness Hadron Beams
        (HB2010), Morschach, Switzerland.
[7] S.Peggs et al, Conceptual Design of the ESS-Scandinavia, Proceedings of PAC09, Vancouver, BC,
       Canada, 2009, pp. 1485-1487.
[8] See http://www.euronu.org/.
[9] S. Henderson, SNS Progress, Challenges and Upgrade Options, Proceedings of EPAC08, Genoa,
        Italy, 2008, pp. 2892-2896.
[10] X. Ding et al, Optimized Parameters for a Mercury Jet Target, Proceedings of PAC09, Vancouver,
        BC, Canada, 2009, pp. 2748-2750.
[11] C.J. Densham et al, The Potential of Fluidised Powder Target Technology in High Power
        Accelerator Facilities, Proceedings of PAC09, Vancouver, BC, Canada, 2009, pp. 1833-1835.
[12] See for example http://en.wikipedia.org/wiki/Spallation.
[13] See http://myrrha.sckcen.be/.
[14] See http://www.akersolutions.com.
[15] J. R. J. Bennett et al, Journal of Nuclear Materials 377 285–289 (2008).
[16] F. J. Zerilli and R. W. Armstrong, Journal of Applied Physics 68(4), 1990, pp 1580-1591.

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[17] Hessler et al, Proceedings of IPAC’10, Kyoto, Japan, 2010, pp 3948-3950.
[18] G. P. Skoro et al, Dynamic Young’s moduli of tungsten and tantalum at high temperature and stress,
        Journal of Nuclear Materials 409 40-46 (2011).
[19] Stupp et al., N Eng J Med 352 (2005) 987-996.
[20] Yamamoto et al, Radiotherapy and Oncology 91 (2009) 80–84.
[21] Detta and Cruickshank, Cancer Res March 1, 2009 69, 2126.
[22] Culbertson et al, Applied Radiation and Isotopes, Volume 61, Issue 5,(2004), 733-738.
[23] See http://en.wikipedia.org/wiki/Pumpable_ice_technology.
[24] Beasley et al, Proceedings of IPAC’10, Kyoto, Japan, 2010, pp 711-713.
[25] P.Webster (DoH), Private communication.
[26] Z.Y.Guo et al, Proceedings of LINAC 2004, Lubeck, Germany, pp 312-314.
[27] Ciavola et al, Proceedings of LINAC 2002, Gyeongju, Korea, pp 676-678; Hollinger et al,
        Proceedings of LINAC 2006, Knoxville, Tennessee USA, pp 232-236; Belchenko et al,
        Proceedings of the Second Asian Particle Accelerator Conference, Bejing, China, 2001, pp 849-
        851.
[28] Letchford et al, 22nd Particle Accelerator Conference (PAC07), Albuquerque, NM, USA, 2007,
        1634-1636.
[29] Y. Itow et al, The JHF-Kamioka neutrino project, hep-ex/0106019, 2001.




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