Characterization of large frustum CsI(Tl) crystals...
Transcript of Characterization of large frustum CsI(Tl) crystals...
FAIR (Facility for Antiproton and Ion Research)
Characterization of Characterization of large frustum CsI(Tl) crystalslarge frustum CsI(Tl) crystals
for the Rfor the R33B CalorimeterB CalorimeterMartín Gascón
H. Alvarez, J. Benlliure, , D. Cortina, I. Durán Universidad de Santiago de Compostela, Spain
R3B Calorimeter
The calorimeter array will surround the R3B target, measuring both gammas (0.510 MeV in CoM) and protons (up to 300 MeV).
Concerning gammas, it must fulfils two requirements: to provide the ray multiplicities and their sum energy, and for other experiments, it must measure the individual ray energies for spectroscopic purposes.
On the other hand, the detector has to stop and measure the total energy of energetic light charged particles with good energyresolution
In order to ensure the nominal values of the requirements in all the angular domain, the polar angular segmentation and the thickness of the scintillation material will be optimize for separate angular regions.
New accelerator facility in Darmstadt (Germany) p,stable and radioactive ion beams Primary intensity 1012 ions/s @ 230 GeV/u Good beam quality (cooling techniques)
CALIFA: A Calorimeter for in-flight emitted gammas and light charged-particles for R3B Experiment
Conclusions
Detector requirements (Technical proposal for the design of R3B - 2005)
CsI(Tl) 13 cm long
(1) FAIR Project. www.gsi.de/fair/(2) R3B Technical Proposal. wwwland.gsi.de/r3b(3) R3B Gamma Calorimeter Development. Universidade de Santiago. www.usc.es/genp/
References
SORMA WEST 2008 – Symposium on Radiation Measurements and Applications. Berkeley, California, USA 25 June, 2008SORMA WEST 2008 – Symposium on Radiation Measurements and Applications. Berkeley, California, USA 25 June, 2008
R3B is a versatile experimental setup for full kinematics studies of exotic beam reactions at relativistic energies ( ~700 MeV/nucleon in the laboratory system)
4 s is a tradeoff between loss of energyresolution
and avoiding pileup effects.
Best values are obtained between 20 and 50 seconds
depending on the counting rate.
CsI(Tl) Crystals TestsCsI(Tl) Crystals Tests
We observe important differences between the light collection non uniformity and energy resolution for the two samples coming from the same provider.
The samples offering the “best records” in the visual inspection evaluation are not necessary correlated with the best values for light collection non uniformity and energy resolution.
The best results in energy resolution are related with low light collection non uniformity. We can establish an accepted threshold of light collection non uniformity around 2 % (this point is being evaluated with light collection simulations).
A 13 cm long crystal, ESR (VM2000) wrapped , coupled to an APD, inside the Faraday Box for test purposes
Best and worst cases ( gain adjusted to match the
same photopeak channel)
Experimental setup
Bias-voltage dependence Shaping time
Non-Uniformity in Light Output
FAIR and R3B experimentFAIR and R3B experiment
M E A S U R E M E N T S
Energy resolution
Ten crystals samples from five manufacturers have been tested. P1P2P3P4P5 labels the different manufacturers and (S1S2) correspond to different samples from each provider.
CsI(Tl) Crystals TestsCsI(Tl) Crystals Tests
Bi-frustum crystal coupled to a LAAPD
Photopeak position vs. bias voltage
for a particular detection system
Acquisition time
Energy resolution as a function of the bias voltage
Sample TranspP1-S1 B B B Y 1,5 9,3P1-S2 M B B Y 4,5 6,8P2-S1 G M G Y 2,2 6P2-S2 E M G Y ---- 6,8P3-S1 M M B N ---- 8,3P3-S2 M M B N 2,3 6,6P4-S1 B M M N 1,8 6,5P4-S2 B M M N 4,3 7,7P5-S1 E G G Y ---- 7,3P5-S2 E G G Y 10,4 8,7
Cuttingedge
Surface Mech. tolerances
LONonU (% )
Best DE/E (%)(γ-ray 662 keV)
LOmax/min stands for the highest/lowest
photopeakchannel LOave is the average of all the
recorded LO values.
ProviderP1 1,1/4,5P2 2,2/---P3 ---/ 2,3P4 1,8 / 4,3P5 ---/10,4
G (%) S1/S2
Lightoutput nonuniformity for different crystal samples.
ProviderS1 S2
P1P2P3P4P5
E/E % (optimal shappingtime)
9,3 (3µs) 6,8 (4µs)6,0 (4µs) 6,8 (6µs)8,3 (3µs) 6,6 (4µs)6,5 (4µs) 7,7 (4µs)7,3 (4µs) 8,7 (4µs)
Average energy resolution ( @ 662 keV) for crystals from different providers
Summary of results obtained within this work. B stands for bad, M for moderate, G for good and E for excellent. Y and N
corresponds to those samples with dimensions respecting the SS ISO 27681m standard.
Nonuniformity ( best and worst cases )
Next Steps
Simulation of the detector response with a light production, transport and collection program (Litrani) to optimize the crystal geometry
To perform in beam measurements with a prototype
20x10 mm2 S86641010 APD from Hamamatsu
Energy resolution vs .photon energy measured with Co60, Cs137 and Bi207radioactive sources
Tests ofTests of