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Thermoluminescent dosimetry at the IFJ Krakow

P. Bilski, B. ObrykINSTITUTE OF NUCLEAR PHYSICS (IFJ), KRAKÓW, POLAND

RADMON, 15 February 2006RADMON, 15 February 2006

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belongs to Polish Academy of Sciences

-founded 1955-450 personnel (180 with Ph.D.)- main research interest: particle physics nuclear physics theoretical physics solid state physics interdisciplinary research-facilities: V-d Graaff (2.5 MeV proton) cyclotron (60 MeV p, 30 MeV d)

Thermoluminescent dosimetry at the IFJ Krakow

P. Bilski, B. ObrykINSTITUTE OF NUCLEAR PHYSICS (IFJ), KRAKÓW, POLAND

RADMON, 15 February 2006RADMON, 15 February 2006

ifjifj

Thermoluminescent dosimetry at the IFJ Krakow

40 years of experience in TL dosimetry:

first LiF crystals for dosimetry were developed in Krakow in 1960s

• Research on thermoluminescence phenomena• Development of new materials, detectors and methods• Application of TLDs in various dosimetric measurements • Dosimetric service

Our activities:

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DOSIMETRIC SERVICE

Laboratory for Personal and Environmental Dosimetry (LADIS)

• Started in 2002

• Accredited according to the ISO/IEC 17025 standard

• 13000 monitored persons or environmental sites

- including 1000 CERN dosimeters

Equipment:

3 Rados DOSACUS automatic readers 3 manual readers Rados dosimeter holders

Calibration: with gamma-rays in the accredited Secondary Standard Calibration Laboratory at the IFJ (LWPD)

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Advantages of TLD

Very small dimensions (standard 4.5x0.9 mm, but even < 1 mm3 is possible)

Passive - no cables, no power supply, etc

Wide range of measured doses

Relatively resistant to environmental factors ( e.g. no influence of electric and magnetic field, vibrations; only elevated temperature is a limiting factor)

Practically unlimited period of measurement (years)

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A human phantom exposed outside of the International

Space Station2003-2006

Over 3000 TLDs from Krakow

2.4 years measuring period2.4 years measuring period

Space experiment MATROSHKA

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LITHIUM FLUORIDEThe most widely used TL detector

Two types: LiF:Mg,Ti (”standard”) MTSLiF:Mg,Cu,P (”high-sensitive”) MCP

Tissue equivalent - atomic number close to tissue (important for X-rays)

Li-6 and Li-7 isotopes make it possible to measure a low-energy neutron signal

10-3 10-2 10-1 100 101 102 103 104 105 106 107 108

100

101

102

103

104

Li-6 Li-7

tota

l cro

ss s

ectio

n, b

neutron energy, eV

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ECAL

Tracker

Pixel

HCAL / MUON

Cavern

1.E-04 1.E-02 1.E+00 1.E+02 1.E+04 1.E+06 1.E+08

Cavern

HCAL / MUON

ECAL

Tracker

Pixel

Dose/Year [Gy]Ch. Ilgner, RADMON, July 2006

DOSE RESPONSE OF TLDsCMS expected dose range

What doses can be measured with LiF TLDs?

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1µGy 1mGy 1Gy 1kGy 1MGy Dose

DOSE RESPONSE OF TLDs

0.1 1 10 100 10000

1

2

LiF:Mg,Ti

SIgn

al /

dose

Dose [Gy]

linearity limit limit of measurementpossibility

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1µGy 1mGy 1Gy 1kGy 1MGy Dose

1µGy 1mGy 1Gy 1kGy 1MGy Dose

DOSE RESPONSE OF TLDs

0,1 1 10 100 10000,0

0,2

0,4

0,6

0,8

1,0limit of measurement

possibility

S

igna

l / d

ose

Dose [Gy]

LiF:Mg,Cu,P - main peak

linearity limit

10-4 10-3 10-2 10-1 100 101 102 103 104

0.0

0.2

0.4

0.6

0.8

1.0

1.2

10-4 10-3 10-2 10-1 100 101 102 103 104

study 1998 study 2004 study 2005

Rel

ativ

e re

spon

se

Dose [Gy]

LiF:Mg,Cu,P

LiF:Mg,Ti

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1µGy 1mGy 1Gy 1kGy 1MGy Dose

1µGy 1mGy 1Gy 1kGy 1MGy Dose

DOSE RESPONSE OF TLDs

LiF:Mg,Cu,P

LiF:Mg,Ti

100 150 200 250 300 350 400 450 500 550 6000,0

0,2

0,4

0,6

0,8

1,0

TL s

igna

l [ar

b. u

nits

]

Temperature, oC

1 kGy

0 – 1 kGy

1 - 50 kGy

50 – 500 kGy

100 150 200 250 300 350 400 450 500 550 6000,0

0,2

0,4

0,6

0,8

1,0

TL s

igna

l [ar

b. u

nits

]

Temperature, oC

1 kGy 10 kGy

100 150 200 250 300 350 400 450 500 550 6000.0

0.2

0.4

0.6

0.8

1.0

TL s

igna

l [ar

b. u

nits

]

Temperature, oC

1 kGy 10 kGy 500 kGy

LiF:Mg,Cu,P thermoluminescence glow-curves

? ? ? ? ?

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DOSE RESPONSE OF TLDs

LiF:Mg,Cu,P

0 – 1 kGy

1 - 50 kGy

50 – 500 kGy

1µGy 1mGy 1Gy 1kGy 1MGy Dose

???

from µGy to MGy => 12 orders of magnitude!

0.01 0.1 1 10 100 1000

0-250 oC 250-350oC 350-550oC

TL s

igna

l [ar

b. u

nits

]

Dose [kGy]

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THE PROPOSED LHC DOSIMETER

One test detector to check the dose level - read out automatically

natLiF:Mg,Ti

One „high-dose detector”, to be read out by special procedure

7LiF:Mg,Cu,P or natLiF:Mg,Cu,P

Two detectors for lower/intermediate doses: e.g. 6LiF/7LiF pair

Its results will decide about choice of readout method for the rest of detectors

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CERF October 2006 RUN

12Gy25Gy28Gy 14Gy

17.5Gy48Gy

45Gy15.5Gy

6 exposures: 4.1 Gy3.6 Gy3.7 Gy3.7 Gy110 Gy

55 Gy

Preliminary results

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CONCLUSIONS

• IFJ Krakow is technically well prepared for dosimetric measurements for LHC

• The newly developed method using LiF:Mg,Cu,P detectors enables measurements far above 1kGy, i.e. the present TLDs’ dose limit

• Further calibrations at the highest doses are planned