P. Pakhlov (ITEP) presented by G.Pakhlova EKLM status Reminder: EKLM general layout & past years...
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Transcript of P. Pakhlov (ITEP) presented by G.Pakhlova EKLM status Reminder: EKLM general layout & past years...
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
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
20/06/2014 2/19
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, 1.3×1.3mm2; 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”
20/06/2014 3/19
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’13WLS 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 produced20/06/2014 4/19
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.20/06/2014 5/19
of the first half of 2014 was/is
The main task
assembly and installation
it is almost done!
20/06/2014 6/19
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
20/06/2014 7/19
LogisticsShipping 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 preamplifiersWayne 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.
20/06/2014 8/19
Preparing framesDeinstallation 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 layers20/06/2014 9/19
Assembly
20/06/2014 10/19
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.
20/06/2014 11/19
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.TestsAfter 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.
20/06/2014 12/19
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!
Conservative estimate (TDR):direct measurements of background at
KEKB tunnel & dose, scaled with luminosity
Present Monte Carlo simulation
Neutron background rate at 0.5 MIP threshold
measured: hottest 6Hz/cm2 @ L=1.5×1033/cm/s extrapolated: ~160kHz for the longest strip in the outermost layer @ L=8×1034/cm/s
~140 kHz for the most noisy strip
Doze, accumulated at SiPM after 10 years of operation
measured: 1.5mSv/week @ L=1.5×1033/cm/s extrapolated: ~40 Sv/10 years @ L=8×1034/cm/s
<< 1 Sv/10 years
The long-standing MC puzzle:
20/06/2014 13/19
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).
20/06/2014 14/19
Summary
20/06/2014 15/19
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
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 &
20/06/2014 16/19
Dmitry Liventsev
Ushiroda san
Leo Piilonen
David Cinabro20/06/2014 17/19
Gary Varner
20/06/2014 18/19
to ITEP engineers
who worked on R&D, construction, mass production…
20/06/2014 19/19
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