Faculty of Physics, University of Belgrade Collaboration meeting CERN, 24 th of September 2015 ToF-LR status and future Jovan Puzović, Faculty of Physics, Belgrade

Faculty of Physics, University of Belgrade Collaboration meeting, Page 2 out of 10 Jovan Puzović, Belgrade SHINE team ToF-R Status -During the last 6 years ToF-R performs well, especially after changing HV system during In 2009 (pp158) had 24 dead pixels, some of them due to bad HV -In 2011 had 34 dead pixels, due to the HV -In 2013 (BeBe30) had 20 dead pixels, after some intervention on HV (repairing distributors) -In 2015 (ArSc) had 18 dead pixels, after changing entire HV system -It seems that ToF-R can be use for the years to come without problems

Faculty of Physics, University of Belgrade Collaboration meeting, Page 3 out of 10 Jovan Puzović, Belgrade SHINE team ToF-L Status -During the past few years ToF-L shows the significant decline in his performance due to aging (pp) – 45 dead pixels (pp) – 87 dead pixels (some of them because HV) (pp) – 77 dead pixels (after repairing distributors) (pp) – 90 dead pixels (ArSc) – 83 (after renovating of the HV using spare parts from ToF-R, restored 27 pixels but lose 13) -Beside dead pixels we have ~30 suspicious pixels with count which is more than 30% different comparing to neighboring pixels -Efficiency of the left wall is <90%, with tendency to go down -Two days ago I had to disconnect 2 more pixels

Faculty of Physics, University of Belgrade Collaboration meeting, Page 4 out of 10 Jovan Puzović, Belgrade SHINE team Reasons -After carefully examination of the reason for rapidly dying of the pixels on the left side we found several different reasons: 1.Broken PMTs on the light contact with scintillator 2.Bad PMT-s (vacuum?) or bad divider (causing overcurrent) 3.Bad connections between PMTs and the patch panel in the TPC hut 4.Bad connections between two patch panels

Faculty of Physics, University of Belgrade Collaboration meeting, Page 5 out of 10 Jovan Puzović, Belgrade SHINE team ToF-L status pixels examined in total 1.13 bad pixels not connected to TPC hut patch panel 2.8 good pixels not connected to patch panel in right place (remapped)! 3.16 pixels have broken connection between TPC hut patch panel and PMT(or broken HV divider), but good connection with readout electronics 4.15 pixels have broken connection between two patch panels 5.4 pixels have both connection broken 6.57pixels have good connection between PMT and readout electronics (dead due PMT) - Some pixels disconnected from HV, with reason

Faculty of Physics, University of Belgrade Collaboration meeting, Page 6 out of 10 Jovan Puzović, Belgrade SHINE team Cassette repair -We opened cassettes H11 and H17 -Replace bad PMTs with the spare one -H11, pixel 7, good connection, HV connected, PMT replaced -Cause overcurrent! Disconnected. -H17, pixel 1, HV Ok, has bad connection, but after removing the cassette, connection OK -H17, pixels 4 and 6, good connections, HV Ok, connection OK, PMT replaced -Only pixel 6 show some signal, but with lot of noise. -Cassette repair unsuccessfully!

Faculty of Physics, University of Belgrade Collaboration meeting, Page 7 out of 10 Jovan Puzović, Belgrade SHINE team Possible upgrade -Produce at least new cassettes with new scintillators and PMTs. Problems: 1.How will produce new cassettes and scintillators, 2.Russian PMTs are obsolete, cannot be found on the market 3.Using Buda wall scintillators needs mechanical adjustment inside the cassette 4.This imply that we have to remove all the cassettes and use good PMTs from the replaced one as a spare for the bad one. Lot of work, with great possibility to broke existing god pixels. Beside this, remaining old scintillators still have aging problem. 5.Calibration of the HV for the new PMTs will take a lot of time (Cosmic?) 6.Check all connections between two patch panels, and produce another backup patch panels with at least connections, and make connections between them (TPC hut and counting room). Space for these patch panels is also problematic. Doesn't look as a good strategy because after this upgrade we will still have 80% of old pixels which will continue to dying! Beside a lot of work and money. Ursula LeGuin: “Heal the wound and cure the illness, but let the dying spirit go.”

Faculty of Physics, University of Belgrade Collaboration meeting, Page 8 out of 10 Jovan Puzović, Belgrade SHINE team Possible upgrade Build the new left wall! Proposal: 1.Use the scintillators of the same size as we have already (optimized from NA49) 2.Use new technology for light detectors: MPPC, SiMP… (HV supply ~70V, cheaper system) 3.Use the already existing mechanical support system, try to integrate new scintillators+MPPC +electronics to present cassette 4.Repair or build new patch panels in TPC hut and counting room 5.Integrate new system to already existing readout chain or to new one (DRS4) R&D money for this (major!) upgrade granted from CB. First step: Establish the ToF-LR upgrade group with all the people (Krakow, Dubna, Geneva, Belgrade…) who want to participate in this project

Faculty of Physics, University of Belgrade Collaboration meeting, Page 9 out of 10 Jovan Puzović, Belgrade SHINE team Software ToDo 1.Analyze discrepancy between dead pixels reports from hardware point of view (our analysis; ToF-R 18 pixels) and software point of view (Szymon, Magda; ToF-R 120 pixels) (bad scintillators positions in database, undocumented cable mixing, bad maping…) 2.Incorporate ToF calibration procedure into Shine framework (Michal Naskret). Started on the beginning of this year, still no visible progress. 3.Incorporate ToF QA into global QA (urgent, not started yet) 4.Incorporate ToF HV monitoring into DSC (not urgent)

Faculty of Physics, University of Belgrade Collaboration meeting, Page 10 out of 10 Jovan Puzović, Belgrade SHINE team THE END