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Introduction - Fermilab by chenmeixiu

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									                    Making More Muons


  mu2e Conversion and higher intensity beams

                     Project X Physics Workshop




                       Chuck Ankenbrandt
                            Fermilab
                       November 17, 2007


November 17, 2007        Chuck Ankenbrandt   Fermilab
                                                        1
                     Game Plan for this Talk
My title (from the organizers) suggests three topics:
 Delivering protons from Project X to mu2e
     I will discuss this only briefly unless there are questions.
 Providing more/better muons than MECO
     This is the main topic of my talk.
     I will present preliminary ideas to induce brainstorming.
 Upgrading the detector for higher rates
     This is under active consideration by the collaboration.
     I will not discuss it here.




 November 17, 2007        Chuck Ankenbrandt   Fermilab
                                                                     2
                     Delivering the Protons
 From the Booster: Cf. Jim Miller’s mu2e presentation
 At similar intensities (~30 kW), but from Project X:
     Cf. Letter to Steering Group: “Using an ILC-Style 8 GeV H-
      Linac for a Muon to Electron Conversion Experiment” by C.
      Ankenbrandt, S. Geer, and E. Prebys (also backup slides)
 Up to ~ 200 kW (full Project X 8-GeV beam power):
  Extract one complete Recycler fill (1 to 4 Linac squirts) in
  a single turn at MI52 and transmit it via P150 line to the
  Accumulator. Inject the beam into the Accumulator using
  multi-turn (7-turn) transverse stacking in both transverse
  planes. That should be feasible because the transverse
  acceptances in the Accumulator are each about an order of
  magnitude larger than those of the Recycler.


 November 17, 2007        Chuck Ankenbrandt   Fermilab
                                                                   3
                     Muon Beam Introduction
 Muon Beams would be useful for …
     National or International Lepton Colliders (NLC or ILC!)
     Neutrino Factories
     Precision Physics beyond the Standard Model
       – Muon g-2
       – Muon EDM
       - m->e + g
       – Muon to electron conversion (mu2e): (focus of this talk)
 Muons, Inc/Fermilab recently got an SBIR grant to explore
  whether innovations in muon cooling can be used to
  improve Stopping Muon Beams, particularly for mu2e.




 November 17, 2007        Chuck Ankenbrandt   Fermilab
                                                                    4
                  Intro., continued: Approximate rates
 An 8-GeV proton beam on an optimized target produces
  about one charged pion of each sign per proton.

Approx. Rates                                                                      mu2e




                         Muon Collider           Nu Factory          From Project X         From Booster


Pbeam, MW                                    2                  2                     0.2                  0.027




Np/sec                             1.56E+15              1.56E+15               1.56E+14             2.11E+13




Mu/p collected                             0.1                 0.1                                     0.0025




fraction cooled                           0.07                0.7?                                            1




Muons/sec                          1.09E+13              1.09E+14                                    5.27E+10




  November 17, 2007                      Chuck Ankenbrandt           Fermilab
                                                                                                                   5
                 Stopping Muon/proton ratio
 Reaction of muon collider community: “Why is the ratio so
  small?”

 Reaction of stopping muon community: “How does
  MECO get such a large ratio?!”




 November 17, 2007      Chuck Ankenbrandt   Fermilab
                                                              6
     More intro.: Comparison of Front Ends

       Those familiar with muon colliders should realize that
       stopping muon beams have very different requirements.

                                 Muon Collider   mu2e Muon Beam

            Cost                 Is no object    Must be reasonable
            Collect both signs   Desirable       Undesirable
            Duty cycle           Pulsed          CW
            Beam cooling         Many stages     Single pass at most
            Reacceleration       Lots of rf      No rf
            Beam contamination   Not important   Important



  (If and when a muon collider exists, a stopping muon program
  could use the cold muon beam when the collider is not operating.)



November 17, 2007            Chuck Ankenbrandt    Fermilab
                                                                       7
                         MECO




November 17, 2007   Chuck Ankenbrandt   Fermilab
                                                   8
                    Stopping Muon Beams 101
     p + A -> p + X
     ~One charged pion of each sign per 8-GeV proton
     Pion decay length is 7.8 meters for p = mc
     p -> m + n decay kinematics in lab:
        Less than 29 MeV/c of transverse momentum
        Longitudinal momentum distribution of muons is uniform between
         about 60% and about 100% of pion momentum
        Polarization correlates completely with longitudinal momentum
 Passing the muons through material causes the momentum
  spread to grow (dE/dx causes longitudinal heating)
 Where the pions are: cf. next slide



    November 17, 2007       Chuck Ankenbrandt   Fermilab
                                                                          9
Momentum vs. Cosine of production angle (from C. Yoshikawa)
Momentum vs. Cosine of production angle (from C. Yoshikawa)




                                                              Alt. B
         MECO

                                                              Alt.A
                                  Concepts
 (a) p/m production
                               a)                         b)

  (b) momentum
      evolution

    HCC acceptance


 MECO acceptance


 SBIR Cooling Concept:
    6D particle density
     increase
    Absorber density
     decrease

 (From Mary Anne Cummings)

    November 17, 2007      Chuck Ankenbrandt   Fermilab
                                                               12
                        However, …
 Above example used collider target solenoid (20 T)
     Not a fair comparison with MECO (5 T)
     Perhaps not practical for mu2e


 Also, collaborators dislike proton beam pointed at detector

 Ergo, explore other concepts:




 November 17, 2007      Chuck Ankenbrandt   Fermilab
                                                                13
         Target + Wedge @ Edge of Dipole


                                                    target
                         Proton beam




                                                             BR=1 Tm
                    Start of match to HCC        wedge




Followed by low-Z absorber in HCC to cool the beam and reduce its energy.




November 17, 2007                      Chuck Ankenbrandt       Fermilab
                                                                            14
                  Advantages of Wedge@edge
     Hard momentum cutoff at ~ 150 MeV/c
     Eliminates wrong-sign particles
     Full width of target magnet is used: magnetic field volume is not wasted
     Particles heavier than muons stop in degrader, not in stopping target;
         thus much better hadron background rejection than in MECO design
     Electrons get eaten by high-Z wedge, thus probably not a problem.
     Better background suppression means might live with higher intensity
     Little dispersion in muon arrival times
     May have better mu/proton ratio:
            Uses pions at peak of momentum distribution
            Uses pions produced near zero degrees
     May be less expensive than MECO (maybe even fly under P5 radar?)
     Probably can operate with shorter deadtime after proton arrival
             =>More usable muons per proton
             =>Could use titanium or other material having Z greater than Aluminum
     Proton beam points away from experiment and is easily dumped.
     Produces polarized stopping muon beam
     Polarization can be varied by changing the thickness of the degrader


    November 17, 2007           Chuck Ankenbrandt   Fermilab
                                                                                     15
          Iron Toroid for Pion Collection




      Cartoon of target toroid (thanks to M. Popovic)




November 17, 2007        Chuck Ankenbrandt   Fermilab
                                                        16
                     Iron Toroid Muon Beam
 One Lint (16.7 cm) of iron alloy magnetized to 2.5 T:
     Attenuates by 1/e (but interactions in it produce more pions)
     Bends 400 MeV/c particle by 312 mr
     Degrades minimum ionizing particles by about 200 MeV/c


 So an iron toroid in the forward direction can:
     Make a parallel pion beam for a selected momentum p*
     Shift the momentum spectra at each prod. angle to peak at p*
     Pick p* to maximize muon flux after HCC at stopping target


 Works much like a DC horn

 Perhaps follow with Dipole+Wedge for muons, then HCC

 November 17, 2007         Chuck Ankenbrandt   Fermilab
                                                                      17
                             Summary
 Project X can supply protons for mu2e
     At Booster intensities, and
     Up to 150-200 kW


 Muons, Inc. and Fermilab are exploring alternatives to
  MECO for pion production, muon collection and delivery.
     Muon cooling via HCC looks promising.
     Effective use of cooling requires different production concepts.


 The mu2e collaboration is considering detector upgrade
  possibilities.



 November 17, 2007         Chuck Ankenbrandt   Fermilab
                                                                         18
                    Backup slides




November 17, 2007   Chuck Ankenbrandt   Fermilab
                                                   19
     Additional Capabilities/Other Compelling Physics
 (The MI-based neutrino program)
 A m->e conversion experiment: mu2e
     wants to momentum-stack in the Accumulator,
     then rebunch and slow-extract from Debuncher.
     It would benefit from cooling of stopping muons.
 A muon cooling experimental program:
     A prototype front end
       – Target station with low beam power
       – Muon collection, cooling, and re-acceleration
     A muon test beam (including slow-spill beam)
     Test concepts and components
 Etc.


 November 17, 2007        Chuck Ankenbrandt   Fermilab
                                                         20
     The original SNuMI connections

                                           AP-4 Line




                                                AP-5 Line




Euclid: “The shortest distance between two points is a straight line.”
November 17, 2007          Chuck Ankenbrandt    Fermilab
                                                                         21
                                          The proposed path

                               MI-20                        MiniBooNE

                MI-22

                                                                                                            Linac
                                                                                                                    Pre-Accelerator

   MI-30                                   MI-10                                      Pbar     I-8    Booster
                                                            MI                        Rings   M
                                                               -8
                                                                                                                               Switchyard


                        Main Injector




                                                                               AP-2
                                                                                        -3
                                                                                      AP
                                                                                                                         F49
MI-32                                                               Target

                                                                                                     P3




                                                                         -1
                                                                       AP
                                               MI-62
                                                                         F17                  Tevatron
                                                       A1
                                                                    P2
                                          MI-60
                                                            F0
  MI-40                                MI-52
                                                P1


        Abort
        Dump
                                                       Fundamental Geography
                           MI-50
                                                       of the Main Injector



The cheapest route between two rings is via existing beam lines.
   November 17, 2007                                 Chuck Ankenbrandt                               Fermilab
                                                                                                                                            22
            MI and RR time lines for NOnA


     Charge          MI Energy
MI
                                        Time, 15Hz


                                       Charge
                                       for MI

RR


                          <-20 Booster ticks->


         The Recycler is empty for as many as 8 Booster ticks.


 November 17, 2007        Chuck Ankenbrandt     Fermilab
                                                                 23
      Bending the beam out of the Recycler



                                                                 RECYCLER



                                                  Q522B                     Q522A




                    MAIN INJECTOR




      (The path into the Recyler will be implemented for NOnA)

November 17, 2007             Chuck Ankenbrandt       Fermilab
                                                                                    24
       Bending the beam into the P150 Line




                            P150LINE




   ~20 mr vertical bend out of Recycler and into P150




November 17, 2007     Chuck Ankenbrandt   Fermilab
                                                        25
                 Matching Recycler to P150 Line




The MAD output for the P150 line. The red arrows indicate the approximate separation between
the two dipole magnets, with the first being in the Recycler and the second in the P150 line.


     November 17, 2007               Chuck Ankenbrandt    Fermilab
                                                                                                26
            Matched Transfer Line from Recycler to P150
      BEAM AT NEL1=    1                                I=   500.0mA                                 BEAM AT NEL2=   14
H A= 2.4000         B= 53.100                  W=8000.0000 8000.0000 MeV                       H A= 0.62846        B= 11.324
V A=-0.80000        B= 14.100                FREQ= 53.00MHz WL=5656.46mm                       V A= -2.9004        B= 67.022
                                            EMITI=    0.900     0.900 3700.00
                                            EMITO=    0.900     0.900 3700.00
                                                     N1=     1    N2= 14
                                                     PRINTOUT VALUES
                                                    PP PE         VALUE
                                                   MATCHING TYPE = 8
                                                DESIRED VALUES (BEAMF)
                                                       alpha       beta
                                                x      0.6000    11.1000
                                                y     -2.9000    66.3000
                                                MATCH VARIABLES (NC=4)
                                                  MPP MPE         VALUE
                                                   1     6     -4.49451
                                                   1     8      4.76013
15.000 mm   X       1.000 mrad                     1     5 8893.92450                          15.000 mm        X        1.000 mrad
                                                   1     7 17000.00000
Z A=-5.00000E-02   B= 1.00000E-02                                                              Z A= 5.07258E-02         B= 1.00000E-02
                                                   CODE:   Trace 3-D v69LY
                                                   FILE:   rrp150.t3d
                                                   DATE:   02/18/2007
                                                   TIME:   14:50:32




 20.000 Deg   X    1000.00 keV                                                                 20.000 Deg           X   1000.00 keV
NP1=    1                                                                                                                  NP2= 14
  10.00 mm (Horiz)       0.0 Deg (Long.)




 B(v)
 E E                                Q                                                  Q                                      B(v)
                                                                                                                              E E
  12 3 4             5                  6                      7                           8                9                       13
                                                                                                                               101112




 10.00 mm (Vert)                                                                                            Length= 40164.98mm


  November 17, 2007                           Chuck Ankenbrandt                 Fermilab
                                                                                                                                         27
                     Synergies with SNuMI
 B->R->AS will:
     eliminate the need for the AP-4 line,
     provide opportunity for early commissioning of momentum-
      stacking in the Accumulator, and
     motivate mitigation of radiation issues in the enclosure.
 Modifications for SNuMI era:
       AP-5 line or equivalent will still be needed.
       There will still be a slot in the Recycler to transport the beam.
       We’ll need a fast extraction system for Recycler to P150 line.
       Only two “free” Booster batches will remain for other programs.




 November 17, 2007          Chuck Ankenbrandt   Fermilab
                                                                            28
                    B->R->AS Requirements
   Two dipole magnets (Cooling Ring Dipoles)
   Two Transrex Power supplies (available)
   Two quads such as existing Recycler quads
   Two trim dipoles and two trim quads
   All these components are available




November 17, 2007        Chuck Ankenbrandt   Fermilab
                                                        29
        Recent documentation (note contributors)


       Delivering Protons to the Antiproton Source after the Tevatron
                                Collider Era
         Charles Ankenbrandt, David Harding, David Johnson, David McGinnis, and Milorad Popovic
                                                Fermilab

                                             March 6, 2007



                                                  …
       Communications with Dixon Bogert, Bruce Brown, Steve Geer, Nancy Grossman, Dave Neuffer,
       and Eric Prebys contributed to the development of the ideas presented here.




November 17, 2007                    Chuck Ankenbrandt           Fermilab
                                                                                                  30
                     Abstract=Summary
 “A way to deliver 8-GeV protons from the Booster to the
  Antiproton Source via existing enclosures and beam lines
  is described. By using the existing 8-GeV line and most of
  the Recycler as parts of the beam path, the scheme avoids
  the need for new civil construction and new beam transport
  lines. In this way, as soon as the Tevatron Collider era is
  over, the Antiproton Source can be rapidly transformed
  into a very useful pair of proton storage rings for various
  applications.”




 November 17, 2007      Chuck Ankenbrandt   Fermilab
                                                                31
            Momentum-stacking in the Accumulator
 “Self-Bunching of a Coasting Beam in the Accumulator”
                     by Dave McGinnis
 Conclusion of that paper:
        “For the projected SNUMI intensity of 14.1x1012 particles in
         the Accumulator at a 95% momentum spread of 15.9MeV, and
         an RF feedback gain of 14dB, the beam should be stable with a
         factor of two margin. This result can be tested by cooling
         100mA of antiproton beam on the stacking lattice (h=0.10) to a
         frequency width of 7.9 Hz.”
 B->R->AS would enable commissioning of momentum
  stacking in the Accumulator
     http://beamdocs.fnal.gov/SNuMI-public/DocDB/ShowDocument?docid=198




    November 17, 2007           Chuck Ankenbrandt   Fermilab
                                                                           32
                    8 GeV Linac (Project X) and mu2e

                              Chuck Ankenbrandt
                                  Fermilab

                          Mu2e Collaboration Meeting
                               August 1, 2007



                          My Preferred title:
  Linac & Recycler & Accumulator & Debuncher: Consider the Possibilities
                          (Like 1969 movie)




November 17, 2007            Chuck Ankenbrandt   Fermilab
                                                                           33
               Considering the possibilities




November 17, 2007      Chuck Ankenbrandt   Fermilab
                                                      34
                                      Outline
     1) Introduction/Overview

     2) Linac & Recycler & Accumulator & Debuncher:
            Consider the Possibilities
     a) Review/discuss Fermilab BEAMS-DOC-2812-V:
        Using an ILC-Style 8 GeV H- Linac for a Muon to Electron Conversion
           Experiment by Ankenbrandt, Geer, and Prebys
     b) Update of that note

     3) Summary/Conclusions




    November 17, 2007            Chuck Ankenbrandt   Fermilab
                                                                               35
    8 GeV
    Proton sources




                                                  Proton Linac (H-)
                                                     8 GeV?

H-


t



         November 17, 2007   Chuck Ankenbrandt   Fermilab
                                                                      36
                             1) Introduction/Overview
     The question that is addressed is:
     How will mu2e get proton beam in the Project X era?
     In a note to Young-Kee Kim’s Steering Group,
     we (Geer, Prebys, and I) discussed that question.
     In this talk, I will briefly review and update that note.
     For completeness, a copy of that note is included in this document.
     Assumptions that went into that note:
     1) By the time that Project X is commissioned, mu2e will already be running (concurrent with NOnA or SNuMI)
      using beam from Booster to Recycler to Accumulator to Debuncher.
     2) Lab management will want to decommission the present Linac and Booster once Project X is commissioned.
     What’s new since the note was written:
     1) Rumor has it that experts are pessimistic about the feasibility of slow extraction from the Recycler. If verified, that
      would preclude running directly off the Recycler.
     2) Ways have been conceived for using more beam from Project X; variations of option 3a. (Thanks to interesting
      conversations with Tom Roberts and Dave Johnson)
     3) Hence I’ve been thinking more recently in terms of an intensity upgrade rather than a mere continuation of mu2e at
      similar intensities.




    November 17, 2007                          Chuck Ankenbrandt              Fermilab
                                                                                                                                   37
                          Title page of the note
     Using an ILC-Style 8 GeV H- Linac for a Muon to Electron Conversion
      Experiment
     C. Ankenbrandt, S. Geer, and E. Prebys


     Fermi National Accelerator Laboratory, PO Box 500, Batavia, IL 60510
     Abstract


            We describe how the H- beam from an ILC-Style 8 GeV H- Linac can be
      collected, rebunched, and slowly extracted to provide a beam suitable for a muon to
      electron conversion experiment (mu2e). The scheme would permit simultaneous
      operation of the muon program with the future NuMI program, delivering O(1020)
      protons per year at 8 GeV for the mu2e experiment.




    November 17, 2007               Chuck Ankenbrandt     Fermilab
                                                                                            38
                                              INTRODUCTION
     In a communication to the Fermilab long-range steering committee, D. McGinnis [1] has proposed to upgrade the
      Fermilab proton source by replacing the existing Linac/Booster with an ILC-Style 8 GeV H- Linac delivering 9 mA in
      1 ms long pulses at 5Hz. There would be 7 Linac pulses per 1.4 sec Main Injector cycle, each pulse containing 5.7 
      1013 H-. The first 3 pulses would be injected via H- injection into the Recycler. The circulating 1.7  1014 protons
      would then be extracted in a single turn and transferred to the Main Injector to be used for the NuMI program. This
      would leave up to 4 Linac pulses, which could also be injected into the Recycler, available for an 8 GeV physics
      program. Previous notes have described how 8 GeV protons from the Booster can be transferred to the Fermilab
      Antiproton source [2], then rebunched and slow extracted [3] to produce a primary beam suitable for a muon to
      electron conversion experiment [4]. In this note we describe how protons from the McGinnis scheme [1] can be used
      for a muon to electron conversion experiment. We assume that the scheme described in References [2] and [3] to
      deliver protons from the Booster to the Accumulator for the experiment will have already been implemented by the
      time the new Linac is commissioned. It is also assumed that the present Linac and Booster will be decommissioned
      shortly after the new Linac is commissioned, so beam for the experiment would have to come from the Recycler. One
      way to accomplish this would be to run the experiment directly off the Recycler; the other way would be to transfer
      beam to the Accumulator. The two alternatives are discussed in the following paragraphs.




    November 17, 2007                        Chuck Ankenbrandt             Fermilab
                                                                                                                             39
                    Directly off the Recycler (probably not feasible)

     Once per Main Injector cycle, one Recycler fill (5.7  1013 protons) would be used for
      the muon to electron conversion experiment. The protons would be rebunched into about
      7 equally-spaced bunches, then slowly extracted for about 0.7 seconds from the
      Recycler near MI52 and transferred to the Antiproton Source enclosure via the P150
      line. The beam would then be transported directly to the experiment, bypassing the
      Accumulator. That would require a new beamline in the Antiproton Source enclosure
      connecting the P150 line to the transfer line to the experiment. The other three available
      Linac cycles would not be used. This scenario would provide about 50 kW of beam
      power at 8 GeV with a duty cycle of about 50% for the muon conversion experiment. It
      would preclude other uses of 8 GeV beam which require the Recycler.




    November 17, 2007               Chuck Ankenbrandt      Fermilab
                                                                                                   40
                           Recycler to Accumulator
        Various ways to take beam from the Recycler to the Accumulator for the experiment can be conceived. Subsequent beam
         processing in the Accumulator and Debuncher would then be similar to the plan that uses beam from the Booster. a) In one
         scheme, one complete Recycler fill is extracted in a single turn at MI52 and transmitted via P150 to the Accumulator. The beam
         is injected into the Accumulator using multi-turn (7-turn) transverse stacking in both transverse planes. That should be feasible
         because the transverse acceptances in the Accumulator are each about an order of magnitude larger than those of the Recycler.
         That scheme would provide about 50 kW of beam power to the experiment with a duty cycle of about 90%. The three other
         available Linac cycles could be used for other 8-GeV physics. b) Another method would “steal” about 1/7th of the beam destined
         for the Main Injector. The beam occupying one seventh of the circumference of the Recycler would be kicked out and
         transmitted to the Accumulator via the path described previously. No stacking would then be required in the Accumulator. That
         would provide about 21 kW of beam power for the experiment with a duty cycle of about 90%. It would also create a useful
         abort gap in the Main Injector beam. The four other cycles available from the Linac could all be used for other 8-GeV physics.
         c) The third method would “steal” Accumulator-length batches from each of the four Recycler fills not destined for the Main
         Injector. Each of those could then be separately rebunched in the Accumulator, transferred to the Debuncher, and slowly
         extracted over 200 msec. That would provide about 28 kW of beam power for the experiment with a duty cycle of about 50%.
         The rest of these four cycles could be used for other 8-GeV physics.




    November 17, 2007                            Chuck Ankenbrandt                 Fermilab
                                                                                                                                             41
           Update: intriguing options for more proton
                          beam power.
     1) Full 200-kW capability using transverse stacking into the Accumulator:
              a) Take two linac squirts at a time into the Recycler;
              b) Single-turn extract the whole circumference at once ;
              c) Transverse stack into the Accumulator;
              d) Form a single bunch in the Accumulator;
              e) Transfer to the Debuncher;
              f) Slow spill from the Debuncher;
              g) Repeat this process twice per Main Injector cycle.
     2) As above, but using momentum stacking:
              a) Take two linac squirts at a time into the Recycler;
              b) Extract Accumulator-length batches at 33-ms intervals;
              c) Momentum stack into the Accumulator;
              d) Form a single bunch in the Accumulator;
              e) Transfer to the Debuncher;
              f) Slow spill from the Debuncher;
              g) Repeat this process twice per Main Injector cycle.




    November 17, 2007                   Chuck Ankenbrandt        Fermilab
                                                                                  42
                           Email from Nagaslaev
     From vnagasl <vnagasl@fnal.gov>
     Sent Monday, July 30, 2007 8:40 pm
     To ankenbra@fnal.gov
     Subject Accumulator apertures
       Chuck,
       I think principal limitation of the Accumulator acceptance after
     necessary rearrangements would be
     around 20 pimm unnormalized. However, one of the horizontal limitations
     currently is Extraction
     Lambertson (15 pi), and one would need to increase substantially the
     EKIK power in order to bring it
     to 20 pi.
       These numbers are not official.
       Vladimir




    November 17, 2007                  Chuck Ankenbrandt       Fermilab
                                                                                43
                     Summary from beam note
 If the proton source is upgraded with an ILC-style 8 GeV
  Linac, it appears there are several options that would
  enable an intense beam of 8 GeV protons to be provided,
  with the appropriate bunch structure, for a muon to
  electron conversion experiment.




 November 17, 2007        Chuck Ankenbrandt   Fermilab
                                                             44

								
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