Overview of the SHMS System

1
Overview of the SHMS System

• 12-GeV Hall-C Plans Project Status
• Howard Fenker, JLab

2
Top View SHMS HMS SpectrometersSHMS 5.5
Degrees and HMS at 11.5 Degrees
Dipole
Q3
Q2
Q1
Bender
8.5
5.5
Target
Beamline
HMS Spectrometer
3
Cut View through Detectors

• Hall overview including range of motion

4
SHMS Design Parameters
5
The SHMS Magnets
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HB Magnet
HMS Q1
SHMS HB
7
Q1 Magnet
Flange for JLAB Cryo Control Reservoir
40 cm warm bore
Bath cooled coil clamped preloaded
Q1 Pole Coil are conformal map of window
frame magnet
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Q2,3 Magnet Models
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Dipole
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Magnet Status

• Magnets
• HB developing contract with MSU/NSCL
• Q1 Contract awarded 7/8/09 to SMI
• Q2, Q3, D Reviewing Vendor Response
• Superconductor
• Reviewing Vendor Response
• Cryoreservoirs
• Bids just in
• Power Supplies
• Finishing Specs for Procurement

11
Shield House Support Structure
Shadow-Shield allows significant weight reduction!
Status cleaning up Reference Design in final
preparation for awarding Engineering contract.
12
The SHMS Detectors

• Trigger Hodoscopes
• S1X, S1Y, S2X scintillator Paddles JMU NSF
  MRI
• S2X Quartz Bars NCAT NSF MRI
• Tracking
• 2x6 Drift Chamber Plane SOS-style HU NSF MRI
• Alignment Stands for above CWM NSF MRI
• PID
• Noble Gas Cerenkov (NGC) Ar/Ne UVa NSF MRI
• Heavy Gas Cerenkov (HGC) C4F8O U. Regina
  12GeV (NSERC?)
• Preshower/Shower Calorimeter Pb-Glass Yerevan
  12GeV
• p/K Cerenkov x2 Aerogel Catholic U. / Ms State
  MRI?
• Cerenkov Gas Controls Xavier U. of La DoE
  EPSCOR?

13
Trigger Hodoscopes

• S1X, S1Y, S2X Scintillator Hodoscopes will use
• 131314 40 paddles (BC408) fishtails
• 10cm wide w/0.5cm overlap
• 52 Philips 2262 w/JLab bases
• 28 ET PMTs (9814B or 9214B) and bases.

14
Trigger Hodoscopes
S2Y 21 Quartz Bars 2.5cm thick 5.5cm
wide 0.5cm overlap ET9814QB and XP2020
S1X, S1Y, S2X Mounting Detail
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Drift Chambers
10cm x 6.35cm cell as in SOS HKS
SOS Resolution 180 microns
60
U
U
X
X
V
V
X-plane PCB Artwork
16
Calorimeter Top View
(Engineering coordinates !)
Preshower Counter (re-used SOS blocks)
Shower Counter (re-used HERMES blocks)
Preshower width Module (lg.blockPMT) 97.0
cm Space for cables 10.0 cm Total
width 2 x107 214 cm Shower width 14
Blocks 14x9 126 cm Max. width 214 cm
17
HERMES BlocksPMTs are already at JLab and
undergoing cosmic-ray tests
Elements from low-rate regions of HERMES
Calorimeter selected for use in the SHMS.

• COSMIC RAY TEST _at_ JLab
• 100 blocks performed to date.
• Problems in 20 blocks found and fixed (Arthur
  Mkrtchyan).
• Test of remaining blocks in progress.

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Calorimeter Mounting Assembly
Shower Counter
Preshower

• At least two persons will be needed to stack
  shower blocks.
• Front window of shower counter (honeycomb) must
  be sufficiently strong to hold pressure of 224
  blocks.
• Need at least 1-1.5 gap between Shower and
  Preshower.

19
Noble Gas Cerenkove/p separation for Pgt5 GeV/c

• 2.5 m long gas radiator in simple enclosure at 1
  atm.
• Four mirrors --- each 75/2cm tall x 80/2cm wide.
• Four 5 PMTs at top and bottom (Hamamatsu R1584).

20
Heavy Gas Cerenkovp/K separation for Pgt3.4 GeV/c
Gap between the set and K curves takes into
account the SHMS momentum bite and a possible 0.1
atm error in the setting of the gas pressure
regulator.
21
HGC Preliminary Design Drawings
22
HGC Preliminary Design Drawings
Hamamatsu R1584 PMT and Adapter (Hardin Optical)
Quartz Viewport
23
Optics Simulations

• Both Cerenkovs are co-ordinating design efforts.
• Available tools
• 2D Raytrace program used in design of HMS
  Cerenkov.
• 3D Geant4 studies making use of 50000 event SHMS
  white spectrum provided by Tanja Horn.

2D Raytrace Output ? R155cm Spherical
Mirrors. ? Asymmetric SHMS envelope
dictates different mirror and PMT placements
for d.
24
Background Estimate Knock-on Electrons

• Major source of background
• Below-threshold particles knock atomic e- with
  sufficient energy to produce Cerenkov radiation.
• Largest contribution from small-angle p-
  scattering, where the Coulomb interaction
  cross-section is large.
• Expected to be larger effect at higher momenta.

Photoelectron Cut 1 2 3 4
Estimate performed for Argon, which is worst case
gas (largest Z). Expect pion rejection rate of
10001 over full momentum range.
25
Electron-Pion Discrimination

• The most stringent requirements arise when the
  SHMS is set to negative polarity.
• Both p-/e- and e-/p- separations are required

Conclusion Most challenging electron-pion
discrimination requirements can be met by
Calorimeter in combination with Noble Gas
Cerenkov.
26
Pion-Kaon Discrimination

• Both p/K and K/p separations are required.
• Aerogel or TOF must supplement Heavy Gas Cerenkov
  at low momentum.

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Detectors in Shield House (standard
Configuration) with heavy gas Cerenkov
Dipole
NG Cerenkov
S1X S1Y
Calorimeter
116 cm
Wire Chambers
Aerogel
S2X S2Y
HG Cerenkov
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Detector Arrangement with FPP in the Shield House
Dipole
NG Cerenkov
S1X S1Y
FPP
Calorimeter
Wire Chambers
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Detector main frame and Cerenkov slid sideways
into service position
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Vertical Section Thru Shield Houseconduits
between detector and electronics
Removable Roof Blocks 5 tons each
Fixed Roof
Cutout for Beamline
Conduit
Computer Floor
Conduit
31
Project Schedule Highlights

• Long-lead procurements moved forward
• Magnets, Cryoreservoirs, Superconductor
• Magnet Power Supplies
• SS/SH Fabrication Details Contract FY10
• SS/SH Procurements moved back to FY12
• 12GeV Detector Funding remains in FY12

32
Project Schedule Status
TODAY
33
SHMS Schedule
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Summary

• Successes
• Magnets Moving Ahead Q1 HB Q2 Q3 D
• Support / Shield Contract soon. Weight reduced.
• Excellent Detector Designs. Passed reviews.
• Detector procurements already started
• Possible contributions beyond scope
• Challenges
• Keep long-lead contracts moving
• Interleave Installation Schedule with 6-GeV