1. P. Pakhlov (ITEP) presented by G.Pakhlova EKLM status  Reminder: EKLM general layout & past years activities  Key challenge of this year: assembly and installation  Future and current tasks: electronics, firmware, tests, software  Summary B2GM @ KEK, 20 June, 2014

2. EKLM general layout 14 forward + 12 backward layers 2 backward outermost layers are filled with shielding: not useful for physics, higher background from backward side 104 sectors should be installed + 6 spare = 110 sectors to be assembled The new system should fit the existing mechanical structure, including sector’s frame and cover sheets 20/06/20142/19

3. EKLM general layout Scintillator strips are produced by “Uniplast” (Vladimir, Russia); this vendor produced scintillator for HERA-B & LHCb’s ECAL; near sub detector T2K; WLS fiber is Kuraray WLS Y-11(200)MSJ multi-clading 1.2mm diameter; SiPMs: Hamamatsu’s MPPC S10362-11-050C, 1.3×1.3mm 2 ; specially designed for T2K near detector; chosen as the most radiation hard among several vendors; The base element is a scintillator strip; Scintillator light is collected by WLS fiber and transported to the photodetector: SiPM SiPM matrix Minor thing: optical gel SUREL(St.Petersburg, Russia); connectors are produced by “Uniplast” 20/06/20143/19

4. Scintillator modules mass production 15 strips are glued to modules, convenient for transportation and assembly production was carried out in ITEP for 1.5 years August’12 – December’13 WLS fiber is processed (cut, milled, mirrored, glued to connector) and then glued with optical gel to the strips groove in total 16500 strips/ 1100 modules were produced 20/06/20144/19

5. Average light yield from near & far ends is 2 times larger than assumed for TDR: 50 p.e. from near end (average over ~8000 long strips) vs 24 p.e. achieved at R&D for TDR Rejection threshold is 1.3 times larger than assumed TDR value Strips quality In total ~2% of produced strips were rejected. Light yield in p.e. # of strips long strips (>2m) rejection threshold short strips (<2m) Improved light collection efficiency is a warranty of robustness of the system against radiation damage, high background rate and of better physics performance. 20/06/20145/19

6. of the first half of 2014 was/is The main task assembly and installation it is almost done! 20/06/20146/19

7. Logistics Scintillator modules; support net & fixings shipped from ITEP Frame & Al covers used from the old RPC system; important stage was disassembly of RPC Cables & connectors purchased by KEK; crimped at assembly Preamplifiers purchased by VPI; pig tail soldering and tests at Wayne State U. SiPMs purchased by KEK 20/06/20147/19

8. Logistics Shipping from ITEP: no big problems except for loss of one sector (sent 110  found at KEK 109)? If fail to find, one spare sector less. minor damages that are repaired at assembly: several SiPM-fiber connectors become loose  glued with epoxy; few nodes of I-beam support net get unstuck after many moves from place to place  glued with cold welding. Shipping of preamplifiers Wayne State U. did not deliver the required soldering & test rate  solved with the kind help of KEK (Ushiroda & Sumisawa): ½ is soldered at Wayne + ½ is soldered by a company, recruited by KEK; test of preamplifiers during assembly by ITEP staff. Much bigger problem was discovered recently: because of 5% dead preamps channels and/or insufficient amount of order, preamplifiers for the last 12 sectors lost. The new batch of missing preamps have been ordered by Wayne SU in May, but they will be produced and shipped to KEK only by the end of July. This delays the completion of assembly and installation by 3 months  interference with CDC group. 20/06/20148/19

9. Preparing frames Deinstallation of forward/backward EKLM RPC modules was carried out in April’13/January’14 Dismounting RPC forward/backward was carried out in November’13/January’14 Processing & preparing frames to reuse done by ITEP technicians November’13– May’14 new holes were drilled, old ones sealed in 112 frames + 8 spare frames will be used to fix polyethylene (note: ×2 more effective than polystyrene) shield in 2 outermost backward layers 20/06/20149/19

10. Assembly 20/06/201410/19

11. Assembly By now produced: 90 (out of 110/109) sectors fully assembled; + 12 sectors half-assembled (no preamplifiers) will be finished in one week, to be resumed for one more week in September Started November’13, still ongoing. 20/06/201411/19

12. Installation 2 sectors were installed in backward EKLM in May’13: test installation. 56 sectors were installed in forward EKLM in April’14: the company worked very efficient – it took only ~ 1.5 week; and very carefully – only one outer connector was broken, immediately repaired. 46 backward sectors to be installed in fall campaign. Tests After installation test with oscilloscope that all channels are live and cosmics is seen at proper rate (>1 Hz at 20 p.e. threshold); No quantative tests of light yield is still possible. 20/06/201412/19

13. Neutron background rate with conservative TDR estimate and with MC simulation (still underestimates neutron background) are roughly consistent, while the MC neutron radiation doze accumulated by SiPMs is ~100 times smaller than in TDR: It was recognized recently (thanks to our COMET colleagues), that in MC simulation we have ignored the important Birks' law! We naively implied that ionization energy converts to scintillation light linearly independent of ionization source, while Birks' law predicts much smaller (factor of 5-7) light yield for neutron- induced (low energy proton) scintillation compared to MIP. Hopefully, this solves the puzzle! The long-standing MC puzzle: 20/06/201413/19

14. DAQ & cosmics tests Minimal firmware at DAQ boards is provided by Hawaii group, which allow to start the system: set HV, thresholds, read out to COPPER. However, to take full advantage of the created KLM (both EKLM and BKLM) system (maximum efficiency, optimal background suppression, robustness, use of the excellent time resolution and amplitude information) much more work on implementation of extra firmware is required: - calibration, adjustment of HV and thresholds, trigger, fit of the signal Plan to start immediately after finish of backward EKLM installation. Need to involve experts from T.Shevchenko INR (Kiev, Ukraine), who are ready to work full time for this job + cooperation with VPI (D.Liventsev). 20/06/201414/19

15. Summary 20/06/201415/19 The important stage is almost finished! After final installation, a hard work on commissioning is expected. However, it is time to many people, who made good job

16. for extremely effective organization of all logistics issues at KEK, (de)installation, disassembly and many-many other important contributions without which it would be impossible to work for our group for training of all new ITEP assembly shifts, work on electronics and after- installation tests, coordination of work between ITEP-KEK-WayneSU-VPI-Hawaii Sumisawa san for their daily work on assembly & 20/06/201416/19 Dmitry Liventsev

17. Ushiroda san Leo Piilonen David Cinabro 20/06/201417/19 Gary Varner

18. 20/06/201418/19 to ITEP engineers who worked on R&D, construction, mass production…

19. 20/06/201419/19 to ITEP stuff & David Besson K.Belonozhenko, B.Bobchenko, Y.Kuznetsov, S.Mineev, O.Kachalina, Y.Novozhlov, E.Novikov, A.Semennikov, A.Frolov, S.Veselov from MEPhI T.Aushev, K.Chilikin, R.Chistov, M.Danilov, A.Drutskoy, P.Katrenko, R.Mizuk, G.Pakhlova, P.Pakhlov, E.Solovieva, I. Tikhomirov, T.Uglov