Status of the RPD project

1
Status of the RPD project

• E. Burtin, CEA-Saclay
• COMPASS Collaboration Meeting, May 11,2007
• Context
• Calibration commissioning set-up
• Test of ring B scintillators at Saclay
• Status of other subprojects
• Ring A
• Readout
• Trigger
• Mechanical support for 2007

2
Context
Ring B
Ring A
3
Context
Late 2006 The whole project was identified as
being very late It was decided
to replace scintillators, PMT and light guides
No trigger readout !
Mechanical design remains a critical
point March 2007 Protvino designer is not
available anymore April 2007 The hadron run
was postponed to 2008

• Decision
• Continue with the counters construction
• Do a calibration/commissioning run with halo
  muons in 2007
• Use a simplified mechanical design to hold the
  2 barrels together

4
Calibration commissioning

• Goals
• Measure characteristics of all counters
• Attenuation length
• Light yield
• Light propagation
• Timing resolution vs position
• Measure time offsets
• With real tracks
• With laser system
• Check DAQ of RPD
• Check proton trigger board
• with halo muons
• set-up installation sept. 24

5
Installation in the hall
Top view
Halo muons
Trigger on coincidence between facing hodoscopes
2.35 m
Si concrete
PT
Side view
PT
-0.5 m
Allow rotation of the barrels by -45, 0, 45,
90
6
Design of ring B scintillators
Thickness 1 cm
At Protvino, light guide fabrication
At Saclay opened one counter, found many small
scratches on the surface
(polishing?)
7
Cosmic ray test bench
PMTs XP 2020 (not brand new) Trigger
coincidence of the 4 references DAQ 1 GHz
sampler (44channels) Analysis waveform
processing
8
Light yield and attenuation

Saclay Protvino Number of ?e ( _at_
1MIP) 60 (cosmics) 120 (hadron
beam) Attenuation length 70-80
cm 85 cm Speed of light in scint.
6.1 cm/ns 6.3 cm/ns
Light yield is low. Same counter ? QE of PMT ?
Method ?
Vladimir Polyakovs concern What is the
fraction of good counters ( gt 60 ph. electrons)?
9
Timing resolution
HV low
1 day per point
Position (cm)
?(tB) 250 ps is achieved at Saclay was 430
ps at Protvino by a diff. method
Production of Ring B scintillators can be
started
?(TOF) 350 ps can be expected
10
Fiber prototype
120cm length, 2 cm thickness, 100 WLS fibers 1.2
mm diameter 90 photoelectrons/MIP (protvino)
Time resolution
Oscilloscope signals
? 330 ps (center)
B scint w/ Light-guide
B Scint w/ Fibers Light-guide
11
Ring A (Mainz Bonn)
15
Geometry 12 counters 50x6.35x0.5 cm3
Received Scintillator Bicron
BC404 PMT EMI 9813B active bases
(Mainz) Magnetic shielding studied soft Iron
and mu-metal Light guides UVT plexiglass
fishtail - cant find a company to make
the material with good size - Fallback
solutions standard plexiglass or twisted UVT
Ready in July
12
Proton trigger (hadron running)
Decision FPGA based solution
VME board V1495 from CAEN Evaluation and
programmation at Saclay CFD Sum splitters
Mainz Bonn Discriminators
Cern pool gt The
board can be tested with halo muon tracks
13
Readout (Saclay Warsaw)
3 F1 TDC channels per PMT (with Time
overThreshold recording) 1 SADC channel per PMT
DAQ elements needed 1 9U VME 1 CPU 4
Catches 16 TDC-CMC
4 TCS receivers
1 multiplexer 3 SADC modules
1
Gesica
2 Odin Slinks 2 fiber
pair links,
No show stopper
14
Mechanical support for 2007
Ring B
Ring A
New central mechanical structure to be
designed and built

• Modify existing structure for new Ring A (6-gt12
  elements)
• Fix to existing support of Ring B

15
Assembly (1)
16
Assembly (2)
17
Assembly (3)
18
Assembly (4)
19
Conclusions

• Ring B scintillators gt start construction
• Ring A gt ready in July
• Readout gt has to be ready for
  sept 15.
• Trigger with hodoscopes, test proton trigger
  board in 2007
• Mechanical support for 2007
• Available surface in experimental Hall
• Rotation (45, 0, 45 90)
• Need to build new system to assemble the ring A
• Ask for green light from the collaboration
• Calibration commissioning set-up in 2007