Transcript R&D on CsI(Tl)

R&D on CsI(Tl) + APD
Optimisation of the energy resolution
M. Gascón
I.Durán
R3B calorimeter
Main characteristics (from R3B Tech Proposal) :
Total absorption efficiency
80 % (Eg=15 MeV lab)
Very large crystals
Eg sum
s(Esum)/<Esum> <10%
(same as DE/E)
g Multiplicity
s(Ng)/<Ng>
DE/E for g
DE/E for p (up to 300 MeV)
Calorimeter for p
< 10%
Moliere Radius
2-3 %
Scintillation properties
Detector granularity
3%
Large crystals
Dynamic range
Large dynamic range for detecting p,g
Inner radius 35 cm ( house Si trackers)
R&D on crystals + readout systems
Design based on CAD + GEANT4 full simulations
see http://www.usc.es/~genp -> calorimeter -> reports and talks
Calorimeter sectors
Due to the Lorentz boost we identify three sectors:
45
130
15
88
ECM = 10 MeV
β = 0.82
Demonstrator meeting, Madrid May-09
Crystals
!?
R3B/EXL meeting Milan Oct-06
Crystals
M. Mozynski et al., NIM A 485(2002)504 (API LAAPD)
Hamamatsu
Photonis
St Gobain
Material we used for test
CsI (Tl)
10x10x10, 10x10x50 ,10x10x100, 10x20x170 mm
CsI (pure) 10x10x10, 10x10x50 ,10x10x100 mm
LaCl3(Ce) 10x10x10, 10x10x50 ,10x10x100, 10x20x170 mm
XP3102
Standard 10-stage, 25 mm tube, borosilicate glass, bi-alkali
XP1918
Standard 10-stage, 19 mm tube, fused silica, UV bi-alkali
XP1901
Standard 10-stage, 19 mm tube, lima glass, Green bi-alkali
S8665-55 (CMS)
5x5 mm
S86641010(PANDA)
10x10 mm
S5345+ API
19 mm2 UV extended (200-1000 nm)
R3B/EXL meeting Milan Oct-06
R&d on crystals and APDs
Crystals from StGobain (France) tested
coupled to LAAPD from Hamamatsu (Japan)
and API (USA)
Data-taking setups

Standard pulse-height analysis :
- preamplifiers: Canberra 2001A, Ortec R142
- Shapping amplifier: Canberra 2022
- Multichannel analyzer: Ortec Maestro or
Amptek MCA-8000
 Pulse-shape analysis :
- Oscilloscope Tektronix TDS3054B
- Off-line Digital filtering: Trapezoidal finite-impulse algorithm
Not used for APDs but providing the best results for PMT!
R3B/EXL meeting Milan Oct-06
Experimental setup
Test at Genp-Lab (USC)
Test at Genp-Lab (USC)
APD gain vs. Bias Voltage
5 cm length
The energy resoltution shows a minimum
when
The APD Bias Voltage=380
The energy resoltution depends on the APD
gain and the Bias Voltage
~380V Dgain/DV= 2.84 %
Dependence on shapping time
For small crystals 4ms is a good compromise between energy-resolution
and pile-up
Dependence on the acquisition time
Best results achieved for acquisition times between 30-60 s
These curves conatin two effects: statistics and bias voltage drift.
Could be solved by controling Temperature and Bias Voltage
Dependence on Amplifier Gain
Energy resolution improves by increasing the amplifier gain
Best results
Study of the non-uniformity
Energy resolution dependence
on the first interaction point
Non-uniformity ~ 8.4 %, to compare
with < 3% measured by St. Gobain
Light collection uniformity CMS CAL
P. Sempere PhD Thesis
CsI(Tl) Resolution
Energy resolution improves
for increasing energy
CsI(Tl) with a
60Co
source
(1171 keV) and (1332 keV)
R3B/EXL meeting Milan Oct-06
Some conclusions
• Several test (wrapping, optical coupling,amplifier gain, shapping time) have been
performed to optimise the energy resolution of CsI(Tl)
•APDs from API showed the best energy resolution for CsI(Tl) crystals
•APDs S8664-1010 from Hamamatsu showed a very good energy resolution
almost independent on the crysal size
• The main drawback of APDs vs PMT is the strong dependence of the gain with
Temperature and Bias Voltage
How to improve the resolution:
-Better stabilisation of both temperature and bias-voltage.
- Better optical coupling --> Scionix
- Surface coating --> Ukranian Institute for Crystals
- New generation of scintillating crystals
T and V dependence
Both Crystals and APDs response depends on Tº
T must be kept very stable ! ~0.1o
otherwise, T should be accurately measured in order to keep gain
constant by controlling the bias voltage
Characterization of S8664-1010 APD
T. Ikagawa et al., NIM A 538(2995) 640
T stabilisation ~0.1ºC keep the gain variarion ~ 0.3%
Temperature stabilisation
Refrigerator 4-5 º C
radiator
Ceramics
Cold focus
~ 10ºC
Resistor warm focus
T probe
T stable within 0.1ºC
Humidity control box < 30% (1%)
T controller
22ºC
Allow pulse shape analysis
with Tektronix TDS3054B
Further tests through prototype
• Good results are only achieved when there is a perfect matching between the
crystal exit surface and the APD entrance area
Type 2
View of the Barrel
average
dimensions
3x1x13 cm
Crystal type-2 Bi-frustrum shaped
Waiting for an agreement with StGobain and IMPLanzhou(China) --> Price drop!
Exit face fits to LAAPD S8664-2010 under negotiation
First prototypes done at Lanzhou (China
Study of St. Gobain vs IMP Lanzhou crystals
Tests performed with API APD
Crystal dimensions 1x1x1 cm
Very similar behaviour
Resolution achieved
IMP Lanzhou
St. Gobain
R3B Type Crystal
Uniformity of the crystal
Wrapped with ESR (from 3M), tested with 60Co
2500
Relative Light-out(arbitrary Uits)
2400
The light-out uniformity is 2.8%
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CsI Position
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