Tests of scintillators

CsI, CsI(Na), BGO, NaI(Tl)

CsI(Tl)

CsI(Na)

170 mm

15 x 15 mm9 x 9 mm

Energy of PMT 1 (small window)

Ene

rgy

of P

MT

2 (

big

win

dow

)

CsI(Na) scintillator with 2 PMT readout

Full absorption

Measurement without collimation 137Cs, 661 keV

Energy of PMT 1 (small window)

Ene

rgy

of P

MT

2 (

big

win

dow

)

CsI(Na) measured with a collimated source

Sum (e

nerg

y)

Ratio (position)

Energy spectrum (sum of 2 PMT’s energies)

Sum of 2 PMTs energies

Energy resolution 9.6% at 661 keVConstant for the position of the interaction

Position resolution (ratio of the PMT’s energies)

Light division between 2 PMTs

15 cm

10 cm

5 cm

Position resolution

0 2 4 6 8 10 12 14 160.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1 Y =0.29835-0.00312 X+0.0029 X2

light

div

isio

n be

twee

n P

MT

s

position in scintillator, cm

Position resolution

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00

2

4

6

8

10

12

14

16

18po

sitio

n in

sci

ntill

ator

, cm

light division between PMTs

Position resolution 1.5 – 3 cm

0.0 0.2 0.4 0.6 0.8 1.00

1

2

3

4

5ab

sorp

tion

dist

ance

, cm

energy, MeV

CsI

Ge

Mean absorption distance

Readout with one PMT

1000 1500 2000 2500 3000 3500 4000 4500 50000

100

200

300

400

coun

ts

energy of one PMT

5 cm

10 cm15 cm

CsI, pure

Energy resolution

Resolution 17 – 19 %

Sum energy

Position resolution

Light division between 2 PMTs

15 cm

10 cm

5 cm

Position resolution

2 4 6 8 10 12 14 16 180.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0 Y =0.32407+0.16521 Xlig

ht d

ivis

ion

betw

een

PM

Ts

position, cm

Position resolution

0.5 1.0 1.5 2.0 2.5 3.0 3.5

2

4

6

8

10

12

14

16

18

20

posi

tion,

cm

light division between PMTs

Position resolution 2 – 8 cm

BGO

Energy of PMT 1 (small window)

Ene

rgy

of P

MT

2 (

big

win

dow

)

BGO scintillator with 2 PMT readoutScintillator was illuminated by Cs137 source (661 keV) without a collimator

Strong nonuniformity of light yieldalong the crystal distance

BGO collimated measurement

Full absorption

BGO collimated measurement

Full absorption

1)Light yield is strongly non uniform along the crystal distance

2)Light separates always in the same proportion between left and right sides

3)Energy resolution ≈18% (big window) ÷ 24% (small window)

BGO results

CsI(Tl)

7% at 661 keV

2.5 cm2.5 cm

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