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Xenon Detector
Xenon Detector Group
Contents
• Cryostat Construction
• Detector Preparation
• Schedule
1
Cryostat Construction
• Xenon Cryostat is NOT DELIVERED YET
Cryostat
Construction
Cold Vessel
•Thin Window Welding
•PMT Support Inst. Test
•Vacuum Leak Test
•Pressure Test
•Cryogenic Test
Honeycomb Panel
Construction
•Pressure Test
•Low-Temp Test
2
Schedule Reported in the Last Meeting
•
•
•
•
Week 19-23 June:
– Warm vessel: Complete welding of all nozzle
(3 days).
– Cold vessel: Complete welding of CF 100
flanges, braze the cooling tube (3 days)
Welding test of the windows (2days)
– New foil fabrications (4 days).
– Define Honeycomb materials and geometry (2
days) delivery (15 days)
Week 26-30 June:
– Test box preparation: warm window test box
(1day); cold window test box (3days).
– Welding of warm window on the test box (2
days) + helium leak test (1day)+ mechanical
test (1day).
– Machining of cold vessel (5 days).
Week 3-7 July:
– Welding of cold window on the test box
(2days)- helium lesk test (1day).
– New honeycomb delivered – mechanical test
cold window (1day).
– Welding window on cold vessel (2days)
Week 10-14 July:
– Test warm vessel (2days).
– Helium test of cold window (1day)
– Honeycomb mounting and cold test
preparation (1day)
– Pressure test cold vessel, 4 bar, (1day)
•
•
•
•
•
•
Week 17-21 July:
– Dry out cold vessel (1day)- helium leak test of
metallic sealing on covers (1day).
– Mounting of the phototube supporting
structure (2days)
– Welding of the L bracket to hold the arches
(phototube supporting structure) (1day)
– Installation of super insulation and
temperature sensors (1day)
Week 24 -28 July:
– Alignment and vessel integration (3days)
– Bellows welding (3day)
Week 31July - 4 Agust:
– Helium leak test on the welds (1day)
– Internal polishing (3days)
– Cleaning and dryout (2days)
Week 7- 12 August:
– Preparation and installation of equipmnets for
the cryocenic test (1day)
– Cryogenic test (4days)
Week 14- 18 August:
– Helium leak test of cold vessel (2days)
– Prepartation of shipmenet (2days)
Week 21- 26 August:
– Delivery to PSI
End Oct
End Dec
3
Why is Cryostat Construction Delayed?
• Thin window welding and related tests
took longer time than expected, which is
now successfully completed.
• PMT support did not fit the cold vessel wall
because of deformation that had appeared
during construction process.
4
PMT Support Installation Test
• Cold vessel construction procedure
Assemble and weld
Thin window welding
Machining
Leak test
Honeycomb panel
Installation into
the warm vessel
• Test was performed on 29/Sep/06, but …
Reality
Ideal
Xenon
coming in.
•Several mm gap
~6mm
Support
structure
cannot
come in
•LXe R.L. 2.89 cm
5
Protocol Update
• Discussion between SIMIC and INFN
– Update schedule including remachining of the
cold vessel wall
– Check points at milestone activities
• He Leak Test, Pressure Test, etc.
– Assign another SIMIC engineer who can
respect the schedule in a cautious manner
– In case of schedule slippage without any
acceptable reason, we will stop SIMIC and
continue at a different manufacturer.
6
Remachining of the Inner Vessel Wall
• Aviolamer (Pianezza, TORINO)
– 6-axis milling machine
– 3D Coordinate Measuring Machine
632.1
631.6
632.0
634.5
635.9
7
PMT Support Installation Test
• The welded thin window was
removed for this procedure
• Scraped away the inner wall
by 5mm at maximum
• PMT support successfully
installed
• Checked with a gap gauge
of 200 mm with the
supporting structure installed
on 22/Jan/2007
8
Vacuum Leak Test with Metal Gasket
•
He vacuum leak test of the cold vessel
with Helicoflex sealing (metal gasket) at a
sensibility of 10-9 cc atm/sec on
14/Dec/2006
•
OK at the upstream side, but not OK at
the downstream side because of
welding
•
Fixed by filling the hall with a metal piece,
and tested again on 18/Dec/2006
9
Pressure Test
•
Test up to 4 bar on 19/Dec
•
Displacement measured at 4 different
locations
•
The test was repeated twice
–
–
1st test OK
2nd test
•
Water leak at the upstream flange,
which was later found to be due to
scratch on the groove.
•
This was fixed and checked in another
vacuum leak test performed on
22/Dec/2006
4 Bar!
10
Comparison with Simulation
• Displacement measured at 4 bar
1.2mm
0.55mm
1
4
3
1.3 mm
Dial. N.1
2
Modeling
1.25mm
1.7 mm
Dial. N. 2
11
Thin Window Welding Again
• The honeycomb panel and PMT structure are used to
guarantee that there is no gaps between them. SIMIC is
now drilling the blind thread holes to restrain the panel.
Thin Window Welding
PMT Holder Inst. Test
Vacuum Leak Test
Pressure Test
•Cryogenic Test
Position of the blind holes
12
Honeycomb Panel
Production
Honeycomb Panel – Brief Retrospect
• The 1st panel broke down in pressure test
as reported in the last meeting
• New (2nd) panel was designed
– Honeycomb thickness 19mm  26.5mm
– High module prepreg 0.75mm 1mm
– Transition with fabric only  Taper
Transition
Honeycomb
panel
Thin window welded
on the cold vessel
1st honeycomb panel
pressure test
1st panel
OK on this side
2nd panel
14
Pressure Test of the 2nd Panel
• Pressure test was stopped at
2.5 bar to check the panel
internal surface
– Small crack on the surface
• The panel was tested again with
proper SIM between the panel
and test box
– Curvature of the panel OK
– Curvature of the test box NO
SIM
SIM
• Succeeded to apply up to 4 Bar
– Repeated 4 times
– Break down at the end
Pressure
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The 3rd Panel
•
•
Internal reinforcement at the edges.
Fiber with lower module but with a better Elongation (T300, used in
aerospace applications with over 20 year service history).
– 1.5mm prepreg thickness with 8 piles (1mm in the 2nd panel
•
Space-approved Resin epoxy (Hysol EA9361)
Internal reinforcement
“Coca-Cola can” shape
16
Construction of the 3rd Panel
• The 3rd panel requires more intermediated construction steps and a
lot of preparation of parts prior to gluing and assembly
1.
2.
3.
4.
5.
Forming the external skin
Forming the honeycomb
Machining the honeycomb
Forming the external skin
Gluing the reinforcement
to the central honeycomb
in the primary mold
6. Gluing the external skin to
the honeycomb using
paste adhesive
7. Gluing the internal skin to
the rest parts with paste
adhesive
Two additional molds are
necessary
External skin
Internal skin
Central
honeycomb
Internal
reinforcement
17
Construction Status of the 3rd Panel
• Delivery to Pisa in this week
• Pressure and low temperature test soon after that before bringing to
SIMIC on 21/Feb
Rohacell
Z reinforcement
Outer Skin
Honeycomb glued to the Z
reinforcement and rohacell
Inner skin
18
Updated Construction Schedule
Cryogenic Test
Shipping to PSI
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Detector Preparation
Xenon Storage
Cables and Related Electronics
NaI Detector for Pi0 Calibration
C-W Proton Acc  Peter’s Presentation
Nickel 9 MeV Gamma Generator
Xenon Storage
•
•
~900L in liquid, largest amount of LXe ever liquefied in the
world
Very stable
–
–
Pressure raise 0.003MPa/h w/o cooling
0.111 MPa  0.2 MPa in 44 hours
GXe pump
(10-50L/min)
Heat exchanger
GXe storage tank
Getter+Oxysorb
Cryocooler
(100W)
LN2
LN2
Cryocooler
(>150W)
Liquid pump
(100L/h)
Purifier
LXe Calorimeter
Liquid circulating
purifier
1000L storage dewar
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Cables and Related Electronics
• Signal and HV cables have
been already laid down
• Signal Splitter and HV power
supply are ready, too
• HV Controller
– GUI for Xe HV control
– Runs in monitor mode of
meganalyzer
– 2D PMT map with markers
– Some more functions
– Will be tested soon with real HV
modules
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NaI Detector for Pi0 Calibration
•
•
•
9 NaI (Tl) Crystals, 62.5x62.5x305mm
Each viewed by 2 APDs (5mm x 5mm)
Electronics Test with MEG DAQ (DRS) at PiE5
–
–
Cosmic-Ray data
Need to improve S/N
•
•
APD with larger active are
2 x 5mm x 5mm  10mm x 10mm
60o
COMIC DRS Data
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24
25
New
Neutron BG Measurement
• Multiple locations with different detectors (PiE5 in Dec/2006)
–
–
–
–
C
Bonner Sphere
NaI activation method with Cd foil wrapping
Total flux 3.7 n /sec/cm2, Thermal flux 0.5n /sec/cm2
Small enough for Xe Detector PMT operation
A
B
m beam
•4” x 4” cylinder;
•activation technique
•thermal and non-thermal
separattion by using Cd-wrapping
method
• Precise measurement of thermal
neutron flux and estimate of non
thermal neutron flux.
•3He counter
•2”, 3”, 5”, 8”, 10”, 12”
spheres
• Neutron energy spectrum
determination:
•sphere response functions
•numerical unfolding codes.
26
m radiative decay
g
e Lower beam intensity < 10
Is necessary to reduce pilem
ups
n
n
Better s , makes it possible
7
t
to take data with higher
beam intensity
(rough) relative
timing calib.
< 2~3 nsec
A few days ~ 1 week to get
enough statistics
p0 gg
LED
Laser
PMT Gain
Higher V with
light att.
p- + p  p0 + n
Can be repeated
frequently
p0  gg (55MeV, 83MeV)
p- + p  g + n (129MeV)
Laser
10 days to scan all
volume precisely
alpha
(faster scan possible
with less points)
e+
LH2 target
Xenon
Calibration
PMT QE & Att. L
Cold GXe
LXe
g
e-
Proton Acc
Li(p,g)Be
Nickel g Generator
LiF target at
COBRA center
K
17.6MeV g
Bi
Tl
F
Li(p, g1) at 14.6 MeV
Li(p, g0) at 17.6 MeV
New
~daily calib.
Can be used
also for initial
setup
off
9 MeV Nickel γ-line
on
quelle
Illuminate Xe from
the back
Source (Cf)
transferred by
comp air  on/off
NaI
3 cm 20 cm
Polyethylene
0.25 cm Nickel plate
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Schedule
• Available online at
– http://meg.web.psi.ch/subprojects/install/xenon.html
•April
•Cryostat delivery to PSI
•Alignment at PiE5
•Start of PMT installation
•May
•Complete PMT installation
•Check electrical connection
•Start evacuation
•June
•Pre-cooling
•Liquefaction
•Purification
•Liquefaction (liquid transfer) will end
on 17/June
After the detector is ready,
1. PMT HV adjust, gain calibration,
and a-source (and Cosmic-Ray)
data acquisition (2 Weeks)
2. Proton Acc DAQ (2 Weeks)
3. p0 run (3 Weeks, 10 Days full DAQ)
17/June End of Liquefaction
4. Radiative m decay run with lower
beam intensity (2 Weeks)
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Summary
• Cryostat construction
– Many problems occurred, but they are getting solved one by one
– Honeycomb panel will be delivered to Pisa in this week and
tested before bringing it to SIMIC
– Cryostat delivery to PSI in April after a cryogenic test
• Detector preparation is in good condition
– Calibration procedures
• pi0
• C-W Acc
• Nickel g
– Neutron measurement performed again
• BG level is expected to be small enough for the xenon detector
operation
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