1. Status of CLAS12 PCAL project
S. Stepanyan
JLAB

2. Agenda of the meeting Project status - Stepan Stepanyan
PCAL cosmic tests, experience with fADCs - Cole Smith
PCAL installation, mounting fixture, schedule - Bob Miller
Plans for EC PMT repairs - Cole Smith
FADC as time measuring device and as a real-time scalers - Sergey Boiarinov/Chris Cuevas
Electronic cables, tests and fixes - Gegham Asryan
AOB
2/20/13
CLAS12 workshop, Feb. 20, 2013

3. CLAS12 PCAL
To contain full shower from high energy (> 6 GeV) electrons and photons, and to resolve close clusters
from high energy p0 decay
Alternating layers of lead sheets (2.2 mm) and scintillator strips (10 mm) with three stereo readout views, UVW (5 layers per readout view), total of 5.5 r.l.
Extruded scintillator strips, 4.5x1 cm2, with two holes along the strip for light readout (FNAL), 84 strips in U-layer, 78 strips in V- and W-layers
Light transport from scintillator to PMT via 1 mm diameter green wave-shifting fibers from Kuraray inserted inside the holes in the strips, 2 fibers per hole
Total number of readout channels 1152 (6x192)
2/20/13
CLAS12 workshop, Feb. 20, 2013

4. CLAS12 PCAL: Status update 02/20/2013
Four out of fully assembled five modules are tested
By the end of the month, cosmic test of the Module-V will be in progress, and stacking of the last module will start
It is expected to complete assembly of Module VI in June, 2013
Four PCAL modules are now ready for installation
Design of the installation is started and should be ready in June-July, 2013
Estimated time for installation, including cabling, is 2-3 weeks/module
ESB
EEL 5 2 1 3 4
2/20/13
CLAS12 workshop, Feb. 20, 2013

5. QA&C: scintillators, fibers, lead sheets
As part of QA&C, the following measurements have been performed for all modules:
Light yield for several points along the scintillator strips for strips L>200 cm (since from the original production piece two scintillators have been cut one with L>200 cm and another L<200 cm, light yield measurements of the longest will determine the quality of the shorter one)
Light transmission of 20% of fibers from each batch
Thickness of lead sheets at several uniformly distributed points
Outcome of QC measurements:
Only one scintillator has been rejected so far, Sector 6, W63, Layer 3 (only 4 layers left to measure, out of 90 layers)
Few lead sheets were rejected due to corrosion, waviness or incorrect dimensions
2/20/13
CLAS12 workshop, Feb. 20, 2013

6. Bad strip: Sector 6, W63, Layer 3
Several measurements have been made with different fibers
Measurements with similar length strip were alternated to make sure system is stable
2/20/13
CLAS12 workshop, Feb. 20, 2013

7. Scintillators and fibers for five modules
Light yield (pedestal subtracted) at the end of the fiber (480 cm from the PMT). Light is generated with small piece of scintillator.
Light yield (pedestal subtracted) at 10 cm from the near edge. Fiber length from the edge of the strip to PMT ~25 cm
2/20/13
CLAS12 workshop, Feb. 20, 2013

8. Lead sheets 28 right angle triangular sheets per module
Thickness at 36 points per sheet is measured using ultrasonic thickness gauge
Design range for thickness mm to 2.31 mm
Note: Graphs include all 36 points of 28 sheets for each module
2/20/13
CLAS12 workshop, Feb. 20, 2013

9. What next Finish test of Module 5 Finish assembly and test of Module 6
Repair PMTs on EC modules in the Hall, cable and check
Install PCAL modules, cable and check
Collect spears and useful leftovers (scintillators, PMTs, dividers, mu-metals shields, connectors, fibers, cables)
Write a geometry document for the reconstruction and simulation software
Write a NIM article
2/20/13
CLAS12 workshop, Feb. 20, 2013