Energy resolution of several scintillating crystals...

Energy resolution of several scintillating crystalsusing differents readout systems

Measurements performed during Jul-Sept 2007 at the GSI

Martın Gascon

Particle Physics DepartamentUniversity of Santiago de Compostela

5th. October, 2007

Martın Gascon Energy Resolution of several scintillating crystals 5th. October, 2007 1

Contents

Tests performed

1 Energy resolution calibration using 1 cm3 CsI(Tl)

2 Energy resolution of CsI(Na) and BGO using APDs

3 Comparison between APDs and PIN Diodes

4 Energy resolution of LaBr3 using PMTs

5 Energy resolution of LaCl3 using PMTs

6 Non-Uniformities measurements

7 Best values obtained for energy resolution


1. Energy resolution calibrationusing 1 cm3 CsI(Tl)


Energy resolution calibration using 1 cubic cm CsI(Tl) + APDExperimental setup

The detector is electrically isolated by a grounded Faraday box

The detector and Preamplifier are placed in a metalic box with a humidity control system

The system is temperature monitorized


Energy resolution calibration using 1 cubic cm CsI(Tl) + APDBias Voltage Optimization

Bias Voltage Photopeak ch. Energy Resol. Photopeak ch. Energy Resol.300 937.3 ± 0.3 4.87 ± 0.08 937.1 ± 0.4 4.90 ± 0.08320 1254 ± 0.5 5.12 ± 0.09 1258 ± 0.5 5.16 ± 0.10340 1698 ± 0.7 5.37 ± 0.10 1705 ± 0.6 4.83 ± 0.09360 2357 ± 0.9 5.23 ± 0.09 2366 ± 0.9 4.79 ± 0.09380 3255 ± 1.3 5.14 ± 0.09 3266 ± 1.2 4.75 ± 0.08400 4517 ± 1.8 4.97 ± 0.08 4527 ± 1.6 4.57 ± 0.08420 6211 ± 2.3 4.62 ± 0.08 6222 ± 2.2 4.54 ± 0.08430 7275 ± 2.7 4.74 ± 0.09 7285 ± 2.7 4.71 ± 0.08

Table: Photopeak position vs Bias Voltage

Spectra for each Bias Voltage are taken twice,in order to check stability and to reduceuncertainties



Not saturated between 300 V and 420 V

There is no minimum in the energy resolution



Bias Voltage Amp. gain Photopeak ch. Energy Resol. Photopeak ch. Energy Resol.360 135 6307 ± 2.3 4.51 ± 0.08 6304 ± 2.3 4.81 ± 0.09370 113 6330 ± 2.3 4.71 ± 0.08 6332 ± 2.3 4.59 ± 0.08380 96 6330 ± 2.2 4.61 ± 0.08 6326 ± 2.4 4.62 ± 0.08390 81 6335 ± 2.4 4.85 ± 0.09 6340 ± 2.3 4.74 ± 0.08400 69 6296 ± 2.4 4.92 ± 0.09 6302 ± 2.3 4.74 ± 0.09410 59 6333 ± 2.3 4.71 ± 0.09 6333 ± 2.3 4.83 ± 0.09

Table: Photopeak position vs Bias Voltage

Varying Bias Voltage and Amplifier gain to keepconstant the photopeak channel

There is minimum of energy resolution around380 V


Energy resolution calibration using 1 cubic cm CsI(Tl) + APDAmplifier Gain

Linear along the whole dynamic range

the higher the Amplifier gain, the better the energy resolution


Energy resolution calibration using 1 cubic cm CsI(Tl) + APDAcquisition Time

There is a statistical deficit below 40 seconds

60 seconds give us a good energy resolution


Energy resolution calibration using 1 cubic cm CsI(Tl) + APDShaping Time

3 µs and 6 µs are a good trade-off


Energy resolution calibration using 1 cubic cm CsI(Tl) + APDFinal energy resolution

Temp. oC Photopeak ch. Energy Resol. Photopeak ch. Energy Resol.24.3 ± 0.1 6156 ± 2.3 4.96 ± 0.09 6154 ± 2.4 4.87 ± 0.0924.3 ± 0.1 6159 ± 2.4 5.08 ± 0.09 6156 ± 2.4 5.04 ± 0.0924.3 ± 0.1 6159 ± 2.3 4.75 ± 0.09 6152 ± 2.3 4.65 ± 0.0924.3 ± 0.1 6157 ± 2.5 4.97 ± 0.09 6155 ± 2.4 4.93 ± 0.0924.3 ± 0.1 6151 ± 2.3 4.81 ± 0.09 6155 ± 2.4 4.86 ± 0.09

Table: Ten spectra acquired for st = 3µs, t = 50s, HV = 380V and G = 105

Temp. oC Photopeak ch. Energy Resol. Photopeak ch. Energy Resol.24.3 ± 0.1 6220 ± 2.2 4.59 ± 0.08 6221 ± 2.3 4.68 ± 0.0824.3 ± 0.1 6219 ± 2.3 4.74 ± 0.09 6219 ± 2.2 4.68 ± 0.0824.3 ± 0.1 6219 ± 2.2 4.60 ± 0.08 6222 ± 2.2 4.59 ± 0.0824.3 ± 0.1 6220 ± 2.3 4.65 ± 0.08 6221 ± 2.2 4.63 ± 0.0824.3 ± 0.1 6216 ± 2.2 4.55 ± 0.08 6219 ± 2.3 4.73 ± 0.09

Table: Ten spectra acquired for st = 6µs, t = 50s, HV = 380V and G = 96

3 µs: Mean value: 4.89± 0.09 - Best value: 4.65± 0.09

6 µs: Mean value: 4.64± 0.09 - Best value: 4.55± 0.08


Energy resolution calibration using 1 cubic cm CsI(Tl) + APDEnergy resolution vs Energy

1170 keV is part of Comptom edge of 1332 keV of 60Co

The energy resolution is function of the square root of the incident energy photon

We used a 60Co, 137Cs and 152Eu sources


Energy resolution calibration using 1 cubic cm CsI(Tl) + APDEnergy resolution

The reported energy resolution obtained is 4.55 % is similar to the obtained in”Optimization of energy resolution obtained with CsI(Tl) crystals for the R3BCalorimeter” M. Gascon et al., Submited to IEEE Transactions on NuclearScience.


Albert Einstein

A theory issomething nobodybelieves, except theperson who made it.An experiment issomething everybodybelieves, except theperson who made it.


2. Energy resolution ofCsI(Na) and BGO using APDs


Energy resolution of CsI(Na) and BGO using APDsExperimental setup

Frustum shape crystals (170 mm length)

All are encapsulated into aluminium shielding

9x9 and 15x15 windows (1mm thick) (Face A and B)

Delivered by Scionix Holland.


Energy resolution of CsI(Na) and BGO using APDsExperimental setup

The detector is electrically isolated by a grounded Faraday box

The detector and Preamplifier are placed in a metalic box with a humidity control system

The system is temperature monitorized


Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Shaping Time - Face A

between 1 and 3 µs the energy resolution is approximately constant

3 µs requires the lowest amplifier gain


Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Acquisition Time - Face A

80 seconds is a good trade-off


Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Amplifier Gain - Face A

Linear along the whole amplifier dynamic range

500 is the situable one


Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Amplifier Gain - Face A and B

Face B provides more light collection

The higher the light collection, the better the energy resolution

300 is selected for Face B


Energy resolution of CsI(Na) and BGO using APDsCsI(Na) - Acquisition Time - Face A and B

The higher the light collection, the better the energy resolution



Energy resolution of CsI(Na) and BGO using APDsBGO - Shaping Time - Face B

between 1 and 2 µs the energy resolution is approximately constant

1 µs requires lower amplifier gain


Energy resolution of CsI(Na) and BGO using APDsBGO - Amplifier Gain - Face B


500 is selected, above this value noise is amplified.


Energy resolution of CsI(Na) and BGO using APDsBGO - Acquisition Time - Face B



African Proverb

Not to knowis bad. Not towish to know isworse.


3. Comparison betweenAPDs and PIN Diodes


Comparison between APDs and PIN DiodesExperimental setup

Filter + Preamp made by GSI

No chance of varying Bias Voltage


Comparison between APDs and PIN DiodesAmplifier Gain

Bad energy resolution

PINs Don’t need High Voltage

Faster stabilization


Comparison between APDs and PIN DiodesAcquisition Time

similar behavior to Hamamatsu

70 seconds is appropriated


Comparison between APDs and PIN DiodesShaping Time

1 µs and 6 µs are minima


Comparison between APDs and PIN DiodesExperimental setup

Canberra 2001A Preamplifier

PIN Diode S3590-08 from Hamamatsu


Comparison between APDs and PIN DiodesBias Voltage

PINs require much lower Bias Voltage

Faster stabilization (stable between 40 V and 80 V)


Comparison between APDs and PIN DiodesBias Voltage

60 V is selected

Energy resolution is 2 % worse for PIN diode


Comparison between APDs and PIN DiodesAmplifier Gain


750 is selected


Comparison between APDs and PIN DiodesAcquisition Time

Similar behavior to Hamamatsu

60 seconds is adecuated


Comparison between APDs and PIN DiodesShaping Time

3 µs and 6 µs are good trade off for both

Pin Diode are too noisy, so that they can not resolve energies below 400 keV

Pin Diode has worse energy resolution, but similar trend for energies above 500keV


4. Energy resolution of LaBr3

using PMTs


Energy resolution of LaBr3 using PMTsR329 - Experimental setup

Brillance 380 (Saint Gobain)

R329 Hamamatsu PMT


Energy resolution of LaBr3 using PMTsR329 - Bias Voltage

Last point is out of the curve


Energy resolution of LaBr3 using PMTsR329 - Bias Voltage

Varying Bias Voltage and Amplifier gain to keep constant the photopeak channel

1050 V is selected


Energy resolution of LaBr3 using PMTsR329 - Amplifier Gain

Not linear for gain higher than 40

36 is selected


Energy resolution of LaBr3 using PMTsR329 - Acquisition Time

120 seconds is selected


Energy resolution of LaBr3 using PMTsR329 - Shaping Time

1 µs and 2 µs are good trade off

after 2 µs saturates


Energy resolution of LaBr3 using PMTsXP1918 - Experimental setup

Brillance 380 (Saint Gobain)

XP1918 Photonis


Energy resolution of LaBr3 using PMTsXP1918 - Bias Voltage

After 1100 V is saturated


Energy resolution of LaBr3 using PMTsXP1918 - Amplifier Gain

Not linear from 40

36 is adecuated


Energy resolution of LaBr3 using PMTsXP1918 - Acquisition Time



Energy resolution of LaBr3 using PMTsXP1918 - Shaping Time

1 or 2 µs are selected


Energy resolution of LaBr3 using PMTsXP1918 - Energy resolution

4.11 % is the lowest energy resolution without saturation.


Energy resolution of LaBr3 using PMTsXP1918 - Energy resolution

The presented by Saint Gobain resolutions could be saturated

The relation between Photopeak channel/Compton is higher


5. Energy resolution of LaCl3using PMTs


Energy resolution of LaCl3 using PMTsExperimental setup

R329 PMT from Hamamatsu

Brillance 350 - 10 cm LaCl3 (1 and 2 windows)


Energy resolution of LaCl3 using PMTsR329 - Bias Voltage

After 1200 V is saturated


Energy resolution of LaCl3 using PMTsR329 - Bias Voltage

Varying the gain and Bias Voltage

1050 V is adecuated


Energy resolution of LaCl3 using PMTsR329 - Amplifier Gain

linear

40 is selected


Energy resolution of LaCl3 using PMTsR329 - Acquisition Time



Energy resolution of LaCl3 using PMTsR329 - Shaping Time

1 or 2 µs are selected


Energy resolution of LaCl3 using PMTsR329 - Amplifier Gain

Covering the window with aluminized mylar

linear

60 is selected


Energy resolution of LaCl3 using PMTsR329 -Energy resolution

5.78 % is the best energy resolution achieved.


6. Non-Uniformities measurements


Non-Uniformities measurementsExperimental setup

To collimate the source, we use Lead blocks of 5 cm length


Non-Uniformities measurementsNon-Uniformity definitions

Non Uniformity in the Ligth Output

is one of the factors worsening the energy resolution

at least, 2 methods are used to define it: G and δ

Definition of G

G =LOmax − LOmin

LOmed(1)

Definition of δ

LOLOmed

= 1 + δ(x − xmed

xmed) (2)

Notes

δ-value is independent of the number of measuring points, but G does not

infinite number of measuring points means G = 2 · δExample:

For a 10 cm lenght crystal, if we measure 9 points every 1 cm, we get:G = 1.6 · δ

(1) D.M. Beylin, et al., Nucl. Inst. and Meth., vol. A541, pp 501-515, 2005.(2) G. Ren, X et al.,Nucl. Inst. and Meth., vol. A564, pp 364-369, 2006.


Non-Uniformities measurements10 cm CsI(Tl) + APD + PMT

Spectra were taken using Cs-137 and Co-60 sources

Fitting the photopeak channel from the 1332 MeV gamma of a Co-60 source



G = 16.7 %; δ = 9.28% for 10 cm CsI(Tl) + HAMA

G = 9.6 %; δ = 5.33% for 10 cm CsI(Tl) + XP1918



Increasing the PMT gain and plotting as a function of distance to APD

Using a 1332 keV of Cobaltum 60 source (5 min/point)



Doing the sum of the photopeak channel for both


Non-Uniformities measurementsCsI(Na) - Non Uniformity in light collection - Face B

Collimated source of 60Co by 5 cm of Lead

Face A produced few light to perform this test


7. Best values obtainedfor energy resolution


Best values obtained for energy resolutionEnergy resolution

Crystal lenght Readout Premplifiera Shaping Bias Volt. Energy Resolutionb

CsI(Tl) 1 cm APDc Canb. 2001 6 µs e-m 4.50%

CsI(Tl) 1 cm Pin GSI-Preamp 6 µs - 18.7%

CsI(Tl) 1 cm Pin Canb. 2001 6 µs e-m 6.45%

CsI(Tl) 10 cm APD Canb. 2001 6 µs e-m 5.36%

LaBr3 3 cm R329 - 2 µs Wenzel 4.54%

LaBr3 3 cm XP1918 - 2 µs Wenzel 4.11%

CsI(Na) 17 cm APD Canb. 2001 3 µs e-m 17.1%

BGO 17 cm APD Canb. 2001 1 µs e-m 23.7%

LaCl3 10 cm R329 - 1 µs Wenzel 5.70%

LaCl3 (2w) 10 cm R329 - 1 µs Wenzel 8.35%

aThe Amplifier used was Ortec 572bEnergy Resolution for the 662 keV photon of a Cs-137 sourcecAPD is S8664-1010 from Hamamatsu


Conclusions

The calibration showed that the energy resolution value of 4.5 % is repeated with different electronicchains

The enery resolution of CsI(Na) and BGO are bad because its bad quality

The used window for the frustum like crystals produced an energy resolution worsening

There is difference of aproximately 4 % in the energy resolution between Face A and B in frustum likecrystals

The Filter and Preamplifier made by GSI for Pin Diodes don’t offer an energy resolution comparable toCanberra Preamplifier

Pin Diodes don’t need High Voltage, are stable between 40 and 80 V, have an energy resolution of 6.5% for 662 keV photons

Pin Diodes has worse energy resolution for low shaping times and for incident energies below 400 keVthan APDs.

LaBr3 produces so many light in a so short time that saturates common PMT working at tipical voltagevalues

Working at linear gain, the best energy resolution obtained for LaBr3 was 4.11 % for XP1918 PMT fromPhotonis

The best energy resolution for LaCl3 was 5.78 % for the R329 PMT from Hamamatsu


Bibliography

Technical Proposal for the Design, Construction, Commissioning and Operation of R3B.http://www-land.gsi.de/r3b/

H. Alvarez−Pol et al. A first proposal for the geometry of the Total Absorption Calorimeterdesign at R3B. Internal Note: R3B CAL 01/05. http://www.usc.es/genp/

C.W.E. van Eijk, P. Dorenbos, E.V.D. van Loef, K. Kramer, H. Gudel ”Energy resolution ofsome new inorganic-scintillator in gamma-ray detectors” Radiation Measurements, vol. 33, pp521-525, 2001.

Hamamatsu Photonics: Photomultiplier Tubes and Related Products

D.M. Beylin, A.I. Korchagin, A.S. Kuzmin, L.M. Kurdadze, S.B. Oreshkin, S.E. Petrov, B.A.Shwartz, ”Study of the radiation hardness of CsI(Tl) scintillation crystals,”Nucl. Inst. and Meth., vol. A541, pp 501-515, 2005.

G. Ren, X. Chen, S. Lu, Z.Li, X. Xue, D. Shen, ”Non-uniformity of light output in large-sizedCsI(Tl) crystals grown by non-vacuum Bridgman method”,Nucl. Inst. and Meth., vol. A564, pp 364-369, 2006.


Albert Einstein

Put your hand on a hot stovefor a minute,

and it seems like an hour.Sit with a pretty girl

for an hour,and it seems like a minute.

That’s relativity.


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