Liquid Xenon Detector

1
Liquid Xenon Detector

• Xenon Detector Group

2
Contents

• Cryostat Construction
• PMT
• Cryogenic/Gas System
• (Calibration ? Carlos presentation)
• Liquid H2 Target and NaI Detector
• Slow Control
• Measurements of UV Light Reflection on Al and
  PEEK
• Schedule

3
Cryostat

• Vessels
• Windows
• Status Schedule

4
Cryostat Construction

• The main construction activities
• The main flanges are assembled, welded and
  pre-machined.
• All parts of the vessels are prepared and
  assembled.
• The cold and warm vessel are leak tested using
  provisory covers.
• The two vessels are machined, providing the
  necessary apertures.
• The windows are welded on the body.
• Leak and pressure tests are performed.
• The phototube support structure is installed and
  adjusted.
• The attachments to fix the structure are welded
  on the cold vessel.
• Temperature sensors and heaters are installed.
• The two vessels are assembled together.
• The connection between them are done. Bellows are
  welded.
• A leak test of those weld is done.
• A cryogenic test is performed.
• Another leak test after the cryogenic test is
  repeated.

Step 1
Step 2
Step 3
Step 4
Step 1
Step 2
Step 3
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Construction Procedure
Assemble and weld Leak test
Machining
Warm
Pressure Leak test
Assemble and weld
Assemble two vessels Weld Chimneys Leak
Cryogenic tests
Install Windows Install sensor, PMT support
attachment, etc.
Assemble and weld Leak test
Machining
Cold
Assemble and weld
Pressure Leak test
Step 1 Step 2 Step 3
Step 4
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Warm/Cold Vessels
Dec/ 2005
Feb/ 2006
Apr/ 2006
Apr/ 2006
7
Leak Test before Machining

• The cold and warm vessels were leak tested using
  provisory covers.
• Cold vessel test 28-29-April-2006, Warm vessel
  8-May-2006
• Some problems were found in the cold vessel
• Excessive deformation were found during the test.
• The provisory covers were only touching the
  flanges. Sealing plaster was used to make them
  vacuum tight.
• An internal structure were added to control the
  deformation of the cold vessel.

No Cover 1Bar Pressure
Outer Vessel OK
provisory Covers

• Finite Element Analysis
• Excessive deformation of the inner flange.
• The real covers maintain the shape.
• However we have a concern on the integrity of
  cold sealing, whether a local slip can occur
  between the cover and flange.

With Cover 1Bar Pressure
8
Machining
1

• Cold Vessel
• Cu cooling pipe will be welded on the back
• Warm Vessel

9
Bellows/Chimneys

• Pressure Test OK
• Up to Dp4Bar

10
Windows

• A thin foil is welded to a 5mm thick intermediate
  frame.
• Backing with a honeycomb/carbon fiber panel for
  the cold window.

Honeycomb/CF panel
Cold Window
Intermediate frame
Honeycomb/CF panel
Weld
Weld
Cross section A-A
0.4mmt window
Al honeycomb
CF
Intermediate 5mm frame
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Window Test Preparation

• A 5 mm intermediate frame was welded to the test
  box.
• After that the frame is cut out and welded to the
  vessel.
• Preparation of test box. 14-May-2006

Warm window test box
Cold Window
Warm Window
Pressure
Pressure
Cold window test box
Honeycomb/CF panel
Leak test
12
Warm Window Test

• One warm window was tested
• Mechanically it was O.K.
• However during the test leak was found
• SIMIC realized that their construction proposal
  for windows was not feasible. They took three
  days to weld the foil to the 5 mm intermediate
  frame and 10 days to find leaks. After that the
  window was leaking during the test.

13
Cold Window Test

• One cold window was tested
• Mechanically it was NOT O.K. ? Next slide
• The welds were leaking.
• SIMIC tried to repair the TIG weld using a
  brazing material, causing a disaster on the
  intermediate frame.

14
Honeycomb/Carbon Fiber Panel Trouble

• Mechanically the honeycomb/CF panel was NOT O.K.
  at Dp3.7 bar. (Design value of the cryostat
  pressure tolerance is 3.0Bar)
• The honeycomb/CF panel broke at one side.
• FEA with sophisticated laminated elements ? OK
• This buckling is attributed to local defects.

OK on this side
15
New Design of the Windows

• New design proposed by SIMIC
• The windows are welded directly on the bodies.
• A leak test is performed on this weld on the
  body.
• This design implies modification of the
  honeycomb

Honeycomb/CF panel
Cold Vessel
Weld
Weld
Warm Vessel
Turn up the edges and weld along them
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New Honeycomb/CF Panel Design
How can we solve the problem on the Honeycomb/CF
panel? Change the material to avoid transition
from the high modulus fiber to low modulus fiber
around the edge and replace the filler
material. We are contacting Hexcel
(http//www.hexcel.com) experts for advice.

• Previous design
• 5 plies of fiber sheets on each side of the panel
• 45/-45/0/-45/45
• Total thickness of 0.7 mm.
• Around the edge we use low modulus fiber sheets
  to make the bend (inter laminar method) and a
  filler material of epoxy with glass micro spheres
  (beads) inside.
• The honeycomb thickness is 19 mm and the density
  is 50 kg/m3.

• New design
• 8 piles of fibers
• Total thickness of 1.0mm
• A thicker honeycomb 24 mm with the same density
  (50kg/m3) to increase the inertia
• A fabric fiber with an intermediate modulus will
  be used to avoid the transition.
• Thus internal reinforcement will be made around
  the edges.

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Xenon Detector Platform Installation

• Movable stage for the xenon detector
• Operating position
• Parking position
• Mounting activity at PSI by Pisa group
• started on 4/June and finished on 9/June
• Tested successfully with 1.60.6 ton weights on
  it.

2
3
1
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Necessary Operation

• After the windows are welded on the two vessel,
  we need to do the following operation
• A leak test on the window welds
• A pressure test closing all the aperture and
  covers.
• After pressure tests of two vessels are done, we
  have to perform a leak test again.
• The PMT support structure is installed and
  adjusted. The attachments are welded on the cold
  vessel.
• A temperature sensors, heaters are installed.
• The two vessels are assembled together.
• The connection between them are done. Bellows are
  welded.
• A leak test of those weld is done.
• A cleaning and hand polishing is done on the cold
  vessel.
• A cryogenic test is performed.
• After the cryogenic a leak test is performed
  again.

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Cryostat Construction Schedule

• 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

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PMT

• Final Delivery
• Insertion to holders
• Room temperature test

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PMT Final Delivery and Test Status

• Newly delivered PMTs (250) in 2006
• LP 4th PMT test
• 100 new PMTs tested, finished on 17/Mar/2006
• Pisa test facility
• Test of 102PMTs finished on 12/May/2006
• 50 more PMTs (delivered in June) will be tested.
• Delivered PMTs (We need 846 PMTs in total)
• 870 PMTs ordered and delivered
• 107 PMTs returned and 120 PMTs will be returned
  (tgt0.3mm) to Hamamatsu
• 264 PMTs delivered for replacement

• Hamamatsu investigated further
• 5 PMTs w/ large tilt but w/o any remaining
  chlorine
• High temp/humidity test ? OK

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PMT Installation
5
6
1
7
2
8
3
4
9
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PMT Installation contd

• Window slope measurement
• Done for all PMTs
• Installation status
• Side 40 (out of 48) holders ready. PMTs with
  large D(0.3mm) have been replaced.
• Once installed, but later Hamamatsu provided
  replacements.
• Outer 18 (out of 22) holders ready
• Inner 18 (out of 24) holders ready
• Top/bottom not started yet
• Inner holders are located in a vacuum chamber (LP
  cryostat) to remove humidity as much as possible
  before installation to the detector

Inner, Outer, Top/Bottom
Side
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PMT test before installing into the detector

• Signal check before installing into the detector
• NIM HV module
• Oscilloscope
• Measurements
• All cable connections are checked simultaneously
• Current (mA) at 800V
• Pedestal distribution

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Assembly hut
Air Filter
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Liquid H2 Target and NaI Detector
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p0 Calibration
Anti Counter

• p-p?p0n
• p0(28MeV/c) ? g g
• 54.9 MeV lt E(g) lt 82.9 MeV
• Need Anti-Counter (NaI) at the opposite side
• Movable to scan the acceptance
• Timing counter (PbScinti) in front of the NaI
  detector for timing calibration
• Another interesting possibility
• Abandon NaI detector in coincidence
• Detect one g with the xenon detector
• Convert another ? in a 0.1X0 converter close to
  the H2 target
• Detect conversion and measure conversion point
  with a special counter
• Measure e branch of the pair in the chambers
• H2 target and NaI detector with a movable stage
  are essential.

g
up
p0
g
down
target
q
Eg
p0
Eg
Requiring qgt170o FWHM 1.3 MeV Requiring q gt
175o FWHM 0.3 MeV
28
Liquid Hydrogen Target

• Liquid Helium Cooling
• Installed to the position through the insertion
  tube
• Thin entrance window (100 micron Mylar)

29
Liquefaction Test

• Several tests
• Super-insulation
• Material of LHe inlet
• In the last test we liquefied some hydrogen
• Terminated because of exhausting available helium

30
NaI Mover Construction

• 3x3 NaI crystals
• For covering the xenon detector acceptance
• /-30cm in z
• /-60o in f
• and /-30o in q
• All motions are motor-driven and remotely
  controllable

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Detector Preparation Status

• 3x3 NaI crystals
• Readout electronics
• APD Hamamatsu S8664-55
• 2 on 1 crystal
• BD voltage 400V, 5mmx5mm
• Pre-AMP GND GN-0261
• (Shaper)
• Temperature monitor and control
• PT100
• Peltier
• Plastic scintillator (Pb converter) with
  fine-mesh PMTs for timing calibration
• Simulation
• Just started

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Cryogenic/gas system
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Cryogenic/Gas system
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Slow Control
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Slow Control

• Xenon Detector System
• Storage
• pressure, valves
• Gas purifier
• valves, flow meter, pressure, pressure reducer
  control
• 1000L dewar
• valves, pressure, temperature, refrigerator
  control, LN2 flow, heater
• Detector
• Valves, pressure, temperature, surface level,
  strain gauge, refrigerator control, LN2 flow,
  heater
• Liquid purifier
• Valves, surface level, level control, LN2 flow
• NaI mover
• Motor control, position sensor

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Scheme
SCS Module 2 Gas Purifier
SCS Module 1 Storage
SCS Module 0 NaI Mover
SCS Module 4 Detector liquid Purifier
MSCB Ethernet Adapter
SCS Module 3 1000L Dewer
Network
Xenon SC Backend PC
Backend backup
Main Slow Control Logging Alarm
Xenon LabView Interface Status History Display
The backend PC handles signals between SCS modules
37
Measurements of UV light reflection on Al and PEEK

• We asked spectroscopic LENS laboratory in Firenze
  to perform some measurements and to provide us
  experimental data about the properties of
• PEEK (used in the inner holders)
• Aluminium (used in the others)
• (we are very grateful to them for their kindness
  and helpfulness).

Reference frame for the measurements qinc
300 ? qref 300 qinc 450 ? qref 00 qinc
600 ? qref -300

• Results indicates
• gt10 reflection on Al
• negligible on PEEK
• Checking with LP data

linc 160 nm (UV light).
Movable optical prism
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Schedule
39
Schedule

• Cryostat delivery at the end of August
• PMT assembly installation and cabling takes 35
  days.
• Detector setup (evacuation, liquefaction,
  purification) takes 45 days
• Detector can be ready in November
• DAQ can be started when liquefaction finishes
• p0 calibration at the end of 2006 run

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Up-to-date Schedule

• Now on Google Calendar (public)
• http//www.google.com/calendar/embed?src3ci8a2d11
  cqeogq7g99j5sssm840group.calendar.google.com