Status of CLAS12 PCAL project S. Stepanyan JLAB

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

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

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

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

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

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

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 2.05 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

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