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The MINOS Far Detector

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The MINOS Far Detector Powered By Docstoc
					NuMI




MINOS




        The MINOS Far Detector

         Cosmic Rays and their neutrinos are
                being collected now.
        How does this work, and of what use is
                      this data?
            Alec Habig, Univ. of Minnesota Duluth,
                 for the MINOS collaboration
NuMI

                      The MINOS
MINOS                 Experiment
                         • Main Injector Neutrino
                           Oscillation Search
                            – Will utilize NuMI beam from
                              Fermilab
                         • Front-to-back nm oscillation study
                            – Produce well-studied nm beam
                            – Measure nm spectrum just after
                              production with “Near Detector”
                            – Measure again 735 km later with
                              “Far Detector”
                         • Beam goes from Fermilab to the
           735 km
                           Soudan Mine Underground Lab

Neutrino 2002, May         Alec Habig                       Page 2
25-30, 2002, Munich
    NuMI




                          The Far Detector
    MINOS



                                      • Steel/Scintillator sampling
                                        calorimeter
T                                          – 5.4 kt, 8m diameter, 31m long
o                                          – 486 layers, each made of:
                                                • 1” steel
F
                                                • 1 cm plastic scintillator
e
r                             8m           – Magnetized to ~1.5 T
m
i
                                      • Design goals
l                                          – ne/nm/p discrimination
a
            15m
                                           – Good energy resolution
b
                                                • For both m and showers
                                           – Good timing, both hit-to-hit and
                                             absolute
    ½ of the Far Detector
                                                • For particle direction and
                                                  synching with Fermilab beam
    Neutrino 2002, May             Alec Habig                                 Page 3
    25-30, 2002, Munich
NuMI




           Far Detector Progress
MINOS




                                        • Construction began
                                          August 2001
                                        • Now up to about plane
                                          #225
                                           – Almost halfway done!
                                           – First half complete in
                                             July when it will be
                                             magnetized
                                        • Taking Cosmic Ray
                                          data as it is built
                                           – Each plane
                                             independently
                                             instrumented
       Plane #200, May 3, 2002
Neutrino 2002, May         Alec Habig                        Page 4
25-30, 2002, Munich
NuMI




                  Particle Detection
MINOS




                                         • 4.1 cm x 8m scint strips
                                           bundled into “modules”
                                             – Light channeled out via 2-
                                               ended fiber
                                         • Each plane’s strips are
                                           90o from the last
                                             – “U” and “V” views
                                         • 17 GeV MC m shown
                                           below from side, in U,V
   28
       28
        20
          20
            20                      From FNAL
                 20
Neutrino 2002, May              Alec Habig                         Page 5
                      28
25-30, 2002, Munich        28
NuMI




                      Multiplexing
MINOS




                               • Light detected by 16
                                 pixel PMTs
                               • 8 fibers per pixel,
                                 ganged together with:
                                     – Maximal physical strip
                                       separation
                                     – Minimal in-PMT cross-
                                       talk
                                Fiber Layout



                                               One of 3 Ham. M16
                                               PMTs in this “Mux Box”
                                16 mm
Neutrino 2002, May        Alec Habig                              Page 6
25-30, 2002, Munich            M16 PMT
    NuMI




               Front End Electronics
    MINOS




• Fibers from each strip end are multiplexed onto PMT pixels
• Signals amplified, shaped, and tracked+held by “VA” chips
   – Calibration charge can also be injected in the same place as PMT
     charge for functionality check and calibration of full electronics path
• Timing information sent upstream from this “Front End” rack




   Neutrino 2002, May              Alec Habig                         Page 7
   25-30, 2002, Munich
NuMI




                      Data Gathering
MINOS



                                    • VME “Master” crate
                                         – VA Readout Controllers
                                           “VARC”s
                                            • Charge from PMTs digitized
                                              by 14-bit ADCs
                                            • Time stamped to 1.6ns by
                                              internal clock
                                         – 2/6 or 2/36 pre-trigger applied
                                         – Hits given absolute GPS time
                                    • Data read out over PVIC
                                      bus to computer room
1 of 16 VME crates                       – 4/5 plane software trigger
Digitizes 72 mux boxes                     applied, hits time ordered
Each w/3 16-pixel PMTs                   – Data formatted in ROOT

Neutrino 2002, May          Alec Habig                          Page 8
25-30, 2002, Munich
 NuMI




                       De-multiplexing
 MINOS




• Scintillator strip ends are multiplexed 8-1 per
  electronics channel
• How to figure out which strip a particle really went
  through?
• Matching hits on both ends of a strip helps in the
  simplest track case
• For multiple hits on a plane and showers:
    – All the different possible “hypotheses” of which strip was really
      hit tested against the possible real physics
    – Best fitting hypotheses saved
• Reconstructing close multiple muons very difficult!

 Neutrino 2002, May             Alec Habig                        Page 9
 25-30, 2002, Munich
NuMI

                      A Cosmic Ray
MINOS                 De-multiplexed
• Success rate for Cosmic Rays:
       – 94% of hits correctly associated with their strips
       – 97% of CR events successfully sorted out




CR m before De-multiplexing                CR m after De-multiplexing




Neutrino 2002, May            Alec Habig                          Page 10
25-30, 2002, Munich
 NuMI




                       Light Injection
 MINOS




• Calibration using controlled light:
    – LEDs illuminate 8-10 calibration fiber ends each
    – Fibers carry light from LED to shine on ends of scint strip fibers
• Varying light levels used to map out detector and
  phototube response
• Regular pulsing at a constant light level during normal
  operations
    – Tracks changing detector response
    – Flags problems with optical path
                                                          Light from calibration
                                                          fibers illuminating
                                                          ends of fibers
                                                          from the scintillator
                                                          where they are
 Neutrino 2002, May             Alec Habig
                                                          bundled Page 11
 25-30, 2002, Munich
       NuMI




                            Cosmic Rays
       MINOS


                                              • As planes are added to the
                                                detector, they contribute to
                                                the data acquisition
                                              • Currently taking Cosmic Ray
                                                data
                                                      – CR rate: 1000 m/strip/month,
                                                        2% stop in detector
                                              • Excellent “beam” for detector
                                                commissioning
                                                      – Real particle data provide end-
                                                        to-end test of all hardware,
                                                        software systems
CR-m light output with expectations
~10 pe at mid-strip (sum of both ends)        • Good calibration source
                                                      – Geometry, gain, timing,
                                                        reconstruction software
      Neutrino 2002, May                 Alec Habig                           Page 12
      25-30, 2002, Munich
NuMI




                      CR Calibrations
MINOS




• Physical plane locations are surveyed as the planes
  are raised
       – CR m draw nice straight lines
       – Residuals to the m fits are not bad with nominal plane
         geometry, excellent with survey-corrected data
• Timing calibrations
       – CR m are nice straight lines moving at b=1
       – Use this physics to find and fit absolute timing offsets

                                               Timing offsets (ns) vs. channel.
                                               Different delays in different
               Need t0 fit plot                electronics paths are
                                               clearly seen, as is the few (2.6)
                                               nanosecond resolution
Neutrino 2002, May                Alec Habig                        Page 13
25-30, 2002, Munich
NuMI




                      Initial n Searches
MINOS




                                          • Atmospheric n are
                                            present in the data
                                             – Contained vertex search
                                               being refined
                                             – Up-going m search
                                               underway as part of CR
                                               timing calibrations
                                          • Reconstruct timing of m
An up-m!                                    tracks
                                             – Down-going CR’s have
                                               b=1
                                             – Up-going n-induced m
                                               have b=-1
Neutrino 2002, May           Alec Habig                       Page 14
25-30, 2002, Munich
     NuMI




                           Summary
     MINOS




                                                • The MINOS Far
                                                  Detector construction is
                                                  nearing the ½ way point
                                                • Data being taken as the
                                                  detector grows is used
                                                  to validate and calibrate
                                                  both hardware and
                                                  software
                                                • Will be ready for beam
                                                    – Plus atmospheric n work
                                                      can be done with
                                                      magnetic field!
                                                         • n/n separation

First n! An up-going m seen on the evening      The presenter gratefully acknowledges support
      Neutrino 2002, May           Alec Habig                                     Page 15
of March 2002, 2002 – MINOS works!
      25-30, 22, Munich                         for this poster from the National Science
                                                Foundation via its RUI grant #0098579

				
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posted:9/28/2011
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