Xenon Detector Status Report
Xenon Detector Group
Contents
• Liquid Phase Purification
• PMT R&D final report
• Detector Preparation Status
• Cryostat Construction
• 1000 liter dewar
• Xenon transfer
• Gas phase purifier
• Liquid/gas transfer
• PMT test at Pisa & PSI
• Pi0 calibration
• NaI detector stage
• Target
• Xenon
• Waveform analysis update
• Schedule
2/55
Liquid Phase Purification
3/55
Circulation Scheme
Purifier Cartridge
Molecular sieves,
13X 25g water
Pressure
Temp
Freq. Inverter
OMRON
230V
50Hz
PT
PMT’s
Temperature Sensor
Circulation starts
4/55
Specification
• Purifier cartridge
• 500cc cartridge filled with Molecular sieves (13X)
(1/16inch pellet type, 25g water can be absorbed)
• The cartridge can be regenerated by heating before
operation (Watlow heater)
• Pump
•
•
•
•
Centrifugal low temperature fluid pump (Barber Nichols)
Δp=0.2MPa
53Hz operation, 3175rpm
100liter/hour, 5000 hours operation  more than 600
times purification cycle of 800 liter xenon
5/55
Result
•
•
•
16/Feb
17-19/Feb
21-23/Feb
•
24-26/Feb
•
•
•
•
•
•
Pre-cooling
Liquefaction
Liquid pump test
Pump speed 53Hz (3180rpm)
Purification test
Pump on/off, gas-phase purification
26/Feb-4/Mar
5-8/Mar
6-9/Mar
10/Mar
Long-term operation
Gas-phase purification
γ’s from Ni, Al, N nuclei
Recovery
1m
2.5m
5m
Alpha data
before Starting Purification
Pump Operation
In ~10 hours, λabs ~ 5m
6/55
Comments and Remarks
• During evacuation before liquefaction, liquid nitrogen pipe
was cooled to keep water contamination in the cryostat.
• Contamination level is calculated to be > 150ppb.
• Liquid level was monitored by measuring temperature
above the pump head.
• 52W cooling power is usually required to operate the LP.
When the pump is operated, 2.4 times cooling power was
needed (estimated with LN2 consumption rate)  62W
additional heat load.
• ΔPV = 0.2 MPa x 100 liter/h = 55W
7/55
Purifier Design
•
•
•
•
Xenon from the bottom bypass the wall
to the pump/purifier.
Reuse the cover plate used in the LP test.
Simple cylindrical cryostat.
Delivery in Oct/05.
8/55
PMT R&D Final Report
Photocathode R&D
First Ver.
Second Ver.
Third Ver.
Photocathode
Rb-Cs-Sb
K-Cs-Sb
K-Cs-Sb
Material to
reduce surface R
Mn layer
Al Strip
Al Strip (doubled)
Q.E. @ 165K
~6% (LP data)
~16% (LP data)
~4 times g.t. 1st Ver.
(Tokyo data)
Rate dependence
Output deterioration
Stable
10/55
Base circuit R&D
First Ver.
Gain fluctuation
under high rate B.G.
Second Ver.
Zener diode implemented
Stable under high B.G.
but noise appears
Third Ver.
Filter implemented
noise removed
Stable under high rate B.G.
reported in the last Review
Meeting
Tested in Pisa
11/55
Mission : Finalize the low pass filter design
Low pass filter is built in
by adding resistors serial
to Zener
If the resistance is too small,
filtering will not work.
With too large resistance, the
effect of Zener will be little under
high rate BG environment
Optimum resistance is ~100KOhm, Let’s test !
Test the power of the filter by changing the resistance
Test the gain stability under high rate B.G.
(i.e. rate dependence test)
12/55
Set up
Recommended
from HPK
production side
Type ZR Base
Reference
PMT
PMT #1
241Am
Rate
LED
200KΩ
PMT #2
100KΩ
5zeners
51KΩ
1zener
51Ω
PMT #4
1zener
1zener
1zener
1zener
1KΩ
Filtering
power
PMT #3
1zener
1zener
1zener
13/55
Oscilloscope snapshots & Pedestal RUN
…see how the filter works
Without Filter
… Noise observed, wide pedestal
With Filter,
no noise observed,
narrow pedestal
No noise observed
PMT #1
200KΩ
Filtering
power
Rate
dependence
PMT #2
PMT #4
1zener
100KΩ
5zeners
51KΩ
1zener
1zener
1zener
1KΩ
51Ω
PMT #3
1zener
1zener
1zener
1zener
noise observed
14/55
Rate Dependence Test
Reference PMT
Type ZR Base
Crowding
LED
241Am
LED :
PMT stability
monitor
Reference PMT
PMT with Zener and Filter
R=100KOhm
STABLE up to ~10 micro A
No Zener Diode
[micro A] 15/55
Summary of PMT R&D
•
Photocathode
•
Base Circuit
•
We finalized photocathode R&D last year; K-Cs-Sb + AL strip
•
Zener diode was added to reduce voltage drop under high rate background w/o
increasing heat load from the registers (2nd version base).
PMT performance improved against high rate but unacceptable noise appeared.
Possible solution to the problem of noise from Zener diode was presented in
the last review meeting ;
•
•
Implementation of Low pass filter to base circuit (3rd Version base).
•
•
•
We confirmed that with the 3rd version base circuit, noise from Zener
diode is successfully removed and PMTs show good performance under
high rate B.G. environment.
The design of PMT has thus been finalized.
The results are quickly reported to HPK, and they have started the base
circuit production in March.
Now, PMTs for the final detector are being delivered to PSI and Pisa.
16/55
Detector Preparation Status
•Cryostat construction
•1000 liter dewar
•Xenon transfer
•Gas phase purifier
•Liquid/gas transfer
•PMT test at Pisa and PSI
•Pi0 calibration
•NaI detector stage
•Hydrogen target
•Xenon
Cryostat Status
•Tenders and procurements.
•Cold joints.
•Window status.
•Internal structure.
18/55
Tenders and procurements
Tenders have been organized in three parts:
1. Conventional part
2. Purchasing of the cold sealing
3. Cold and warm windows
SIMIC (http://www.simic.it) has won the tender (1) for the best price
and for other reasons.
This company is going to purchase a low magnetic permeability
stainless steel (<1.008). Furthermore they are going to perform the
cold test at the company.
19/55
Tenders and procurements
However…
•
•
•
The company had a lot of trouble to find the material with the specified magnetic permeability. They tried several
commercial material with no success.
We suggest them to heat treated the stainless steel and they obtain an improvement of magnetic permeability with the
316L.
The material did not meet the specification. Up now they found only the material for the big flanges.
•
•
Low magnetic permeability is achieved when the material are in fully annealed condition bellow 1.02 at 0.02 T (200 G)
A special material with low magnetic permeability can be obtained, but the time was more them six month, with min
quantity of 50 ton.
•
We know that nickel help to form the austenitic phase that is not ferromagnetic and we found that the AISI 310 have a
nickel content higher than the 316L (19-22 % versus 10-14%).
Finally SIMIC checked the permeability and now they are trying to acquire all
material before August to recovery the time lost. (Estimated delivery date is
the end of 2005 at PSI.)
We are going to visit them at the end of July to check if the have the material and
they promise us to start cutting the material in the first week of August. So the
welding and the machining of the parts is taking place in September October.
20/55
Our worries on the schedule
Our worries are that SIMIC can not respect the preliminary planning
that was sent us, in which the cryostat will be at PSI at the end of 2005.
The reasons are the following:
• Machining and welding can be done in 2 months.
• Testing the separated parts and assembling them take more than 3
months, even if everything goes well.
• SIMIC has to do mechanical test and leak test of the inner vessel
and the vacuum vessel separately.
• After that SIMIC has to mount two vessel together with installing
the instrumentation and the super insulation.
• SIMIC has to check the additional welding and do cold and leak
tests. Those operations are not simple and require additional tooling
and time.
21/55
Cold joints.
We inquire the specification to three companies:
Those companies are specialized in metallic sealing.
•
•
•
GARLOCK GmbH
High Tech Metal Seals N.V.
Advanced Products NV Parker Seal Group Europe
•
We should have the metallic sealing end of October.
22/55
Window status
We inquire the specification to three companies for the metallic part:
• Zanon
• Cinel
• SIMIC
We are going to supply the material to the companies to build the test
structure.
We inquire the specification to three companies for the honycomb:
• Plyform
• RAV
• SALVER
We should have the windows at the end of October.
23/55
Window studies
•
•
•
The heat treatment of the material was studied in
collaboration with the metallurgic department of Mechanical
and Nuclear engineering of Pisa.
Several mechanical tests were done and several thermal
cycles were made to study the hardening of the material.
We sent the specification to the companies for building the
windows (leaving three option for the construction to be
discussed).
24/55
The window mechanical test
Final thermal treatment
aged 16 h at T= 650°
s=1400 Mpa
25/55
The Internal structure
We try to simplify the machining of the arcs to make them more
precise. We need to make some more iteration in our group to
discuss about some issues like cabling.
Radial holes
Centering system for the lateral structure
26/55
Inner holder Prototype
Cable drain structure
Holder
• Inner holder prototype
• Made of Delrin (POM)
Spacer
• Light material
• Low water absorption
• Easy to machine
Cover
Base & Filler
R
Cable
• Cable embedded in Stycast
for inner slab.
• Cable structure is made using
plastic mold.
• Mold is made of Delrin instead
of metal
• We don’t need to use mold
release which could
deteriorate light yield.
PMT
Delrin mold
• The prototype will be tested
in LXe.
Cable structure prototype
27/55
1000 liter Xenon Dewar
• Delivered to PSI on
20/May/2005.
• Refrigerator, all sensors are
installed.
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
Tom Haruyama, Feb 2003
28/55
Installations to the 1000 liter dewar
•
•
•
Refrigerator/heater installed 4/July/05.
All sensors are ready.
Liquefaction test is schedule in the week of
the review meeting.
29/55
Xenon Transfer Lines
•
Gas phase purifier
•
New system is ready.
Turbo pump
MIDAS slow
controller
Circulation pump
Getter Puri.
30/55
VCR
Vacuum insulated
Xenon Transfer Lines
• Liquid xenon transfer
• Vacuum insulated hose
• Low temperature valve
(bellows sealing)
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
31/55
PMT test status
Pisa PMT facility
•Description of the
Facility
•Description of the
test procedure
•Results on the first
bunch of PMTs
33/55
Usage of the Pisa test facility
•Test of the calorimeter PMT in a
condition as close as possible as the
final experiment
•PMTs immersed in LXe (165 K)
•Am alpha-source
•blue LEDs
•Operated in a safe condition
•No Xe loss
•No night shifts
•Used to study and solve the
“resistivity” problem
•Used to study and solve the “Zener
diode” problem
•Now: mass-test of PMTs
•First 130 PMTs received and being tested
34/55
Principle of operation
•A reference PMT is kept immersed
•The tested PMTs can be easily inserted/removed
without evaporating the xenon
•Particular care in the material choice/cleaning
procedure to minimize xenon contamination
α-source
LEDs
35/55
Test procedure
1.Clean PMT
•Acetone
•Ultrasonic bath
2.Install PMT into linear movement & cross
•leak check
3.PMT warming up to remove moisture
•20 minutes warm GXe “oven”
•10 minutes warm GXe circulation/purification
4.PMT freezing
2h30 per PMT
•Open gate valve & move PMT down
•30 minutes in cold GXe
5.PMT immersion
•measurement cycles
6.PMT recovery
•PMT raised & gate valve closed
•30 minutes warming before opening/replacement
36/55
PMT mass test
•Test of 400 PMTs for the final experiment
•The test is divided in three steps:
1.Measurement of the gain at 800 Volt (g>10^6)
2. Rate dependence test (linear up to 4 uA)
3. QE and timing resolution measurement to classify PMTs
37/55
Gain measurement
•Usual way
•Flashing LED at different amplitudes
•Comparison with Hamamatsu test sheets (Anode
Luminous Sensitivity/Cathode sensitivity)
bad PMT
38/55
Rate dependence test
•The amplitude of LED #1 is measured in presence of a
background current induced by a “biasing” LED #2
•The overlinearity is recorded for each LED setting and
plotted against the current
•A good linearity up to 4 uA is accepted
Reference PMT = no Zener
overlinearity
PMT with Zener
bias on
bias off
39/55
QE test
•Comparison between the alpha-source
light seen by measured PMT and
reference PMT
•Symmetric configuration to minimize
absorption effects
•The test is repeated for at least 2
measured PMT
relative orientations
TEFLON stop
source
reference PMT
40/55
First results
frequency
cumulative tested PMTs
•130 PMTs received at beginning of may
•Results for first 80 PMTs in first 1.5 months (190 tests)
shown
•2.8 PMTs/day
date
PMTs per day
41/55
Results on the web
•As soon as the tests are performed
they are inserted in a MySQL
database and visible from the web
•Click on the link to get a summary
test sheet
•Several tests exist for one PMT in
different conditions (HV/Xe purity/
orientation)
42/55
Data sheet sample
43/55
PMT evaluation
•Several tests are performed on
a single PMT
•We evaluate the PMT
performance by a complete
analysis of the various tests
•Estimate linearity
•Average QE over files
•A particular PMT (ZA1985) is
repeatedly tested once in ten
days to check
stability/reproducibility of
measurements.
...
rms non corrected = 6%
44/55
QE stability/reproducibility
•The QE of a single PMT was measured in different orientation
and for several hours
•The “raw” QE distribution (black) is compared to the QE
distribution of PMTs inside LP during last test (green)
•arbitrary normalization @ 15%
rms = 3.2%
45/55
Energy resolution
•The resolution (right tail) on the alpha source
peak is measured as a function of the charge for
the reference PMT.
46/55
Timing resolution
•The timing resolution of each PMT is measured
with alpha source
•Quite well reproduced by data
47/55
PMT test at PSI
• PMT test in liquid xenon by using
the LP.
• 238 PMTs can be tested at once.
• Long term stability of the LP.
• Purity of xenon can be monitored
in a usual way.
• 2 months for one test
•
•
•
•
PMT replacement
Evacuation/liquefaction
Purification
Recovery
• Preparation of the 1st test started
in June.
• Delay of PMT delivery caused by
base circuit modification.
48/55
PMT test at PSI cont’d
• 30 PMTs tested in the Pisa test
facility will be tested in the LP (1st
test).
• 20 PMTs used in previous tests
are left;
• 12 PMTs in same positions.
• 8 PMTs in the positions
PMTs tested
in Pisa
• with different distance and similar
angle to an alpha source (4)
• With similar distance and different
angle to an alpha source (4)
• Schedule
•
•
•
•
11/July PMT inst. to the cryostat
18/July evacuation
25/July liquefaction & purification
1/Aug~14/Aug test & recovery
Stay
Different d and
similar θ
Similar d and
different θ
49/55
NaI Detector Stage design
Anti
Counter
•
•
•
g
p0
up
NaI detector (~100kg) needs to be moved 2 dimensionally
at the opposite side of the xenon detector.
The movable stage and motor need to be magnetic
tolerable with reasonable positioning accuracy.
Test under COBRA field  OK
Linear slider
Screw drive
No bearing ball
Prism guide
down
g
target
Linear slider: http://www.tollo.com
Motor:
http:// www.animatics.com
Example
Motor
50/55
LH2 target
•All material for test of the first prototype has arrived at Pisa.
•We are assembling the mylar windows.
LHe in
GH2 in
9 cm
5 cm
LH2
support cylinder
Vacuum
copper
LHe out
5 cm
180 cm
51/55
Xenon
• We have 850 liter at PSI !
• 100 liter is on the way!!
52/55
Analysis Update
Waveform analysis
DRS Time calibration & Xe time resolution
•
Domino speed
fluctuated about 2.5%.
•
•
Domino speed fluctuation
Noise subtraction
(This problem will be
fixed with new
mezzanine board)
Using clock channel,
the fluctuation can be
corrected (Time
calibration).
Spike noise is removed
finely!
•
Xe time resolution
(Front 4 PMTs)
improved to 123psec
•
•
Clock channel
Fitting with template
waveform
Time calibration and
spike noise
subtraction were done
No calib
Gain calib
Time calib
TDC
180ps
150ps
123ps
140ps
54/55
Schedule
55/55