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Muon Beamline and Detectors Tracker Calorimeter Cosmic Ray Veto

Muon Beamline and Detectors Tracker Calorimeter Cosmic Ray Veto. George Ginther 14 February 2013. Introduction (adapted from material generated by S. Feher ).

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Muon Beamline and Detectors Tracker Calorimeter Cosmic Ray Veto

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  1. Muon Beamline and DetectorsTrackerCalorimeterCosmic Ray Veto George Ginther 14 February 2013

  2. Introduction(adapted from material generated by S. Feher) • The goal of the Muon Beamline is to facilitate selection and transport an intense beam of low momentum negative muons (~1018 stopped muons during three years of operation of the experiment) to a target, located in the Detector Solenoid, where many of those muons stop • The majority of the stopped muons will be captured by the target nuclei, and many others will decay in orbit into electrons and neutrinos • The intent is to search for evidence of the conversion of stopped muons into electrons • The tracker detects the electrons and suppresses backgrounds through high resolution reconstruction of the electron’s track • The calorimeter and cosmic ray veto detectors provide additional information to identify and suppress backgrounds to confirm the signal (should it occur)

  3. Components • Vacuum enclosures • and associated seals, feedthroughsand vacuum pumps • blanks for pump down tests • Collimators • Muon stopping target • Tracker • Calorimeter • Muon beam stop • Detector support • And support for installation and detector maintenance • Stopping target monitor • Shielding around the TS and DS • Cosmic ray veto detectors • …and associated readout, instrumentation and infrastructure

  4. Muon Beamline Requirements(adapted from materials generated by S. Feher) • Support and align the detectors • Install the detectors • Maintain vacuum in the Production Solenoid (PS), Transport Solenoid (TS) and Detector Solenoid (DS) vacuum space • Prevent migration of radioactive molecules from PS to the detector region • Charge and momentum select particles, preferentially muons, from the particle beam spiraling downstream from the PS to DS • Reduce the heat load to the TS superconducting coils • Protect the detectors from neutron and proton background • Capture muons in the stopping target • Stop the rest of the muons that were not captured inthe stopping target and reduce the background in the detectors generated by the secondary protons and neutrons • Monitor the number of captured muons at the stopping target

  5. Detector Requirements(Summarized from materials generated by A. Mukherjee, S. Miscetti and C. Dukes) • Tracker must have superior position resolution • Minimize material in path of muons • Tracker and calorimeter must be able to function in vacuum and not spoil the vacuum due to leaks/outgassing • Cosmic ray veto must have high efficiency to identify cosmic rays that have the potential to generate signal like events • Minimize penetrations through the cosmic ray veto • Detectors must have good time resolution and handle high rates • Detectors must have low mean times between failures and high uptimes • And survive the accumulated radiation doses • Detectors should be serviceable/repairable in a short time when necessary

  6. Docdb-1383

  7. Tracker • Total of 21600 gas filled straws in 18 stations • 5mm diameter each • 25mm diameter wire in center of straw • Detector is ~3m long • High voltage ~1500V • Argon/CO2 gas • LV power (~20kW) and cooling • High currents (perhaps up to 10kA) • Additional instrumentation for precision monitoring • Magnetic field, temperature and alignment • Clean room for detector during servicing • Local dehumidification (perhaps 5kW) • Chiller and phase separator

  8. Calorimeter • 1936 LYSO crystals arranged in 4 vanes • Each crystal readout with two large area APD’s • Detector is ~ 1.3 m long • High voltage • Laser calibration • Radioactive source calibration • Neutron source bunker

  9. Docdb-2323

  10. Neutron Absorbers(adapted from materials generated by S. Feher) • Standard concrete blocks? • End Cap Shielding designed to be moved downstream to allow access to the detectors inside the DS.

  11. Cosmic Ray Veto • Three layers of extruded scintillator counters with embedded wavelength shifting fibers • Require 2/3 adjacent counters in different layers to define a muon and a ~50 ns veto window • 58 modules, each with 36 counters • 2,088 counters, each with 4 fibers • 16,704 photodetectors: SiPMs • 330 m2

  12. Cosmic Ray Veto Jason Adams, Zach Drumheller

  13. Detector Support Structure S. Feher- DOE CD-1 Review

  14. Infrastructure • Power and cooling for large loads • Emergency power • Climate control (and cleanliness) • Stable base of operation • Support loads/maintain detector alignment • Facilitate operations • Space for signal processing and controls (racks) • Routing of cables and other services---trench • Cryogen and gas distribution • Safety • Radiation (protection and shielding), fire safety, cryogens, Oxygen Deficiency Hazards, magnetic fields, large volume vacuum spaces (confined spaces), high pressure gases, egress paths • Lighting • Access (for receiving, storage and to detector elements) • Materials handling • Crane/house air

  15. Initial Phases of Experiment Operation • Installation • Getting the equipment into place • Locations for pumps, chillers, infrastructure • Routing of services • power distribution • vacuum and cryo lines • signals and controls • Access and clearance for assembly/installation (an ongoing concern) • Staging/storage areas for support equipment/tooling (an ongoing challenge) • Commissioning • Putting the equipment into service • Need to keep detector clean while other activities are underway in parallel • Detectors must be accessible • Operate tracker and calorimeter in service position • Calibration too? • Precision mapping of detector solenoid field • Establishing transmission of muon beam to target

  16. Ongoing Experiment Operations • Operation • Expect to operate around the clock most of the year • Recording data • Calibrations • Select positive muons • Operate detector solenoid at reduced current • Normalization • Anticipate no access to detector level while beam is being delivered • May need to ramp down solenoid to service detector • Anticipate regular need for access (frequency not determined but not likely less than once a month) • Maintenance • Anticipate accessing detectors in DS bore perhaps once a year • Likely a several week operation • Keeping the equipment running at peak efficiency and addressing features observed during operation

  17. Equipment storage during detector opening • External beam stop? • Muon Stopping Target Monitor (and associated supports and infrastructure) • Clean room components • Clean room dehumidifier • Scaffolding or access components (ladders) • Scissors lift (or two)? • Ladders • Detector rail system and supports • Hydraulic pump cart • IFB blank • Tool boxes

  18. Backup Slides

  19. Vacuum System Design Five major components (excluding the beam pipe - part of the Solenoid System): • PS Enclosure • DS Enclosure • Vacuum Pump Spool Piece (VPSP) • Instrumentation Feed-through Bulkhead (IFB) • Cryostat Interconnects • External Vacuum System • dry screw pumps, turbo molecular • cryopumps, pipes, valves • Powering, Monitoring and Interlocks • Above 10-3 torrinterlock at the DS activates: • Tracker HV off • Gate valves for the cryo pumps closed • By-pass valves opened • ----accommodate remote handling S. Feher- DOE CD-1 Review

  20. Collimators Col 5 Col 3d Collimators are made of copper ~1000 kg each Col 3u Col 1 COL3 need to be rotatable To select Positive particles as well for calibration purposes S. Feher- DOE CD-1 Review

  21. Muon Beamline Shielding Design External MuonBeamline Shielding Concrete blocks are envisioned to place around the Transport Solenoid region Exact configuration strongly dependson the cryostat support structure S. Feher- DOE CD-1 Review

  22. Stopping Target Design Stopping Target: 17 flat 200 µm thick pure aluminum discs Tungsten support; low volume, alignment might require extra stiffening S. Feher- DOE CD-1 Review

  23. Stopping Target Monitor Stopping Target Monitor is a germanium detector monitoring muonic X-rays from the capture process outside of the vacuum volume S. Feher- DOE CD-1 Review

  24. Proton Absorber The proton absorber made of polyethylene, is a tapered cylindrical shell 0.5 mm thick with a radius slightly smaller than the inner radius of the tracker. S. Feher- DOE CD-1 Review

  25. Muon Beam Stop Approximate weight: 3300Kg S. Feher- DOE CD-1 Review

  26. Docdb-1383

  27. End Closed(Provided by Jeff Brandt)

  28. Side Views Closed and Open(provided by Jeff Brandt)

  29. Top View Closed(provided by Jeff Brandt)

  30. Top View Open(provided by Jeff Brandt)

  31. Tracker Requirements • Geometric • No mass at r<~40cm, • Low mass for ~40<r<85cm • Performance • High-side resolution for 105MeV/c electron: p< 180KeV/c • Acceptance ≥ 20% • Operation • Low leak rate at 10-4Torr ambient • System MTBF > 1 year • Repair time <2 daysfrom time tracker is accessible to time tracker is ready to reinstall • Tolerate 500kHz/cm2 rate A. Mukherjee - CD-1 Review

  32. Tracker Geometric Requirement Target Measure these Blind to these A. Mukherjee - CD-1 Review

  33. Tracker Resolution Requirement Why asymmetric? • An important background is DIOs, below 105MeV/c • Upward smearing brings background into signal region … bad • Downward smearing moves signal into background … not as bad Signal E (MeV) A. Mukherjee - CD-1 Review

  34. Tracker Conceptual Design • 18 “stations” with straws transverse to beam • Naturally moves readout and support to large radii A. Mukherjee - CD-1 Review

  35. Tracker Straw Assemblies • 100 straws, in two staggered layers, form one panel A. Mukherjee - CD-1 Review

  36. Tracker Straw Assemblies • 6 panels → a “plane” • 2 planes → a “station” • 18 stations in Tracker A. Mukherjee - CD-1 Review

  37. Calorimeter Requirements The calorimeter requirements are described in Mu2e-doc-864. • The calorimeter will be used to confirm that a reconstructed track is well-measured and was not created by a spurious combination of hits in the tracker. • Measure the position of the conversion electron  σ(x) ≤ O( 1 cm). • Compare the energy deposited in the calorimeter to the reconstructed track momentum  σ(E) ≤ O( 2 %). Energy scale small w.r.t. resolution. • Check the time of the energy deposit in the calorimeter to a time determined from the tracker σ(t) O(≤ 1 ns). • Provide particle identification to separate, for example, electrons from muons. • Provide a trigger that can be used for event selection • Keep functionality in a 50 Gy/year radiation environment  L.Y loss < 10% S.Miscetti, DOE CD1 review

  38. Calorimeter Baseline Design • 1936 LYSO crystals arranged in 4 vanes ~ 1.3 m long. • Electrons spiral into the transverse, checkerboard face of the array. • APDs and FEE on back side. • 4 vanes represents the best balance between acceptance and crystal volume (cost). Z= Beam axis Vane dimension: 13x33x132 cm3 Crystal+APD length ~ 13 cm S.Miscetti, DOE CD1 review

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