The Simulation of the quenching factor and the channeling effect for the CsI(Tl) and NaI(Tl) crystals

Juhee Lee and Sunkee Kim 151-747 Seoul National University Shillim-dong Kwanak-gu Seoul Korea, Republic of.

In the saturation model, the scintillation efficiency can be described by the stopping power of an ion and the concen-tration of activated ions. It is supported by the experiments for the electron, proton and alpha(fig.1) and can be ex-tended to other ions of higher atomic numbers. With that relation and the simulation tool, we can reproduce the mea-sured energy spectrum of a scintillation detector. We use MARLOWE and TRIM as BC and MD simulation tools respec-tively. When an ion goes into the symmetric axis or plain, it can interact with only electrons, thus, its penetration and light yield are drastically increased. It is due to the channeling or blocking effect according to the start position of an ion. We can simulate these effects in MARLOWE and estimate the measured energy spectrum with this consideration.

THEORETICAL BACKGROUND

RESULTS

AB-STRACT

Scintillation efficiency

Energy loss functions

Fig.1 Scintillation efficiency of CsI(Tl)Black ones are experimental results and Red ones from calculation.

Fig.2 The electronic Stopping Power in the amorphous CsI

Red line is MARLOWE and Blue line TRIM.

5keV 10keV 15keV 20keV 50keV

[111]13.65.5

11.44.6

10.34.0

9.63.5

7.73.1

[100]12.35.8

10.34.1

9.33.8

8.73.3

6.92.5

[110]9.4

7.9

7.2

6.7

5.32.2

Table.1 Comparing of the axial critical angles A Cs ion goes into the symmetric axes of CsI(Tl).

Black one is Lindhard ‘s 2, Red one of Fig6.

Fig.3 Quenching factors for Cs in CsI(Tl)

Fig.4 Quenching factors for NaI(Tl)

Red is for Na ion and Black for I ion.

Fig.9 Measured energy of tail events

Fig.7 Penetrations from a lattice point

5keV 10keV 15keV 20keV 50keV

[100]14.44.0

12.13.8

10.93.4

10.23.0

8.12.4

[110]12.12.8

10.22.0

9.21.6

8.61.3

6.81.0

[111]9.5

·8.0

·7.2

·6.7

·5.3

·

Table.2 Comparing of the critical angles An I ion goes into the symmetric axes of NaI(Tl).

Fig.6 Initial theta distribution of tail

events

Fig.8 Initial theta distributions of tail events Red <111>, Black<100>, Blue<110>,Brown <ran-

dom>

Fig.5 Penetrations from an empty site Red<111>,Blue<100>,Black<110>