14 Jun

Report
EKLM status
P. Pakhlov (ITEP)
presented by G.Pakhlova
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
20/06/2014
The new system should fit the existing
mechanical structure, including sector’s
frame and cover sheets
104 sectors should be installed
+ 6 spare =
110 sectors to be assembled
2/19
EKLM general layout
The base element is a scintillator strip;
Scintillator light is collected by WLS fiber
and transported to the photodetector: SiPM
• 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;
•Minor thing: optical gel SUREL(St.Petersburg, Russia);
connectors are produced by “Uniplast”
20/06/2014
SiPM
matrix
3/19
Scintillator modules
mass production
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
15 strips are glued to modules, convenient
for transportation and assembly
in total 16500 strips/ 1100 modules were produced
20/06/2014
4/19
Strips quality
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
# of strips
rejection threshold
In total ~2% of produced strips were rejected.
long strips (>2m)
short strips (<2m)
Light yield in p.e.
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
The main task
of the first half of 2014 was/is
assembly and installation
it is almost done!
20/06/2014
6/19
Logistics
Frame & Al covers used from
the old RPC system; important
stage was disassembly of RPC
Cables & connectors
purchased by KEK;
crimped at assembly
Scintillator modules;
support net & fixings
shipped from ITEP
SiPMs purchased
by KEK
20/06/2014
Preamplifiers purchased by
VPI; pig tail soldering and
tests at Wayne State U.
7/19
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.
20/06/2014
8/19
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
20/06/2014
9/19
Assembly
20/06/2014
10/19
Assembly
Started November’13,
still ongoing.
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
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.
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.
20/06/2014
12/19
The long-standing MC puzzle:
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:
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
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 neutroninduced (low energy proton) scintillation compared to MIP.
Hopefully, this solves the 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
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
20/06/2014
15/19
Sumisawa san
Dmitry Liventsev
for their daily work on assembly &
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
20/06/2014
for training of all new ITEP assembly
shifts, work on electronics and afterinstallation tests, coordination of work
between ITEP-KEK-WayneSU-VPI-Hawaii
16/19
Leo Piilonen
Gary Varner
Ushiroda san
David Cinabro
20/06/2014
17/19
to ITEP engineers
who worked on R&D, construction, mass production…
20/06/2014
18/19
to ITEP stuff &
T.Aushev,
K.Chilikin,
R.Chistov,
M.Danilov,
A.Drutskoy,
P.Katrenko,
R.Mizuk,
G.Pakhlova,
P.Pakhlov,
E.Solovieva,
I. Tikhomirov,
T.Uglov
K.Belonozhenko,
B.Bobchenko,
Y.Kuznetsov,
S.Mineev,
O.Kachalina,
Y.Novozhlov,
E.Novikov,
A.Semennikov,
A.Frolov,
S.Veselov
David Besson
20/06/2014
from MEPhI
19/19

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