SOLID STATE DOSIMETRY: State of Art
Helen Khoury
[email protected]
SOLID STATE DOSIMETRY
Luminescent detectors (TLD, OSL, RPL)
Semiconductor detectors
EPR detectors
Track detectors
Gel dosimetry
Superheated emulsions
Radiochromic dyes
Thermoluminescent Dosimetry
The Conduction Band
Eléectron =
Hole =
Radiação
Ionizante
E
N
E
R
G
y
Trap levels
The Valence Band
Termoluminescence (TL)
The Conduction Band
Glow Curve:
1,2
E
N
E
R
G
I
y
V
TL Intensity
1
IV
0,8
0,6
II
0,4
III
VI
I
0,2
0
0
50
100
Recombination
center
150
Temperatura °C
200
250
The Valence Band
THERMOLUMINESCENT DOSIMETRY
LiF:Mg,Ti (TLD-100)
 LiF:Mg, Cu, P (GR-200)
 CaF2
 CaSO4:Dy
 CaSO4:Tm
 Li2B4O7
 MgB4O7:Dy
 MgB4O7:Tm
 Al2O3
~1950
 α-Al2O3:C
Urals Politec. Inst. (Russia), 1990

CONVENTIONAL CRYSTAL GROWING
TECHNIQUES
- Czochralski or Vernuil
Seed
Crystal
Molten
solution
Czochralski
Al2O3 F.P.= 2050ºC
COMBUSTION SYNTHESIS

Synthesis is based on the heat released from the
redox chemical reaction (1500-6500K), instead of
using high-temperature muffle furnaces.
COMBUSTION SYNTHESIS

1 - The samples were prepared by mixing:
Aluminium nitrate (Al(NO3)3.9H2O),
 Urea (CO(NH2)2) as fuel
 Dopants:

Europium nitrate (Eu(NO3)3)
 Terbium nitrate (Tb(NO3)3)
 TEOS (C8H20O4Si)


2 - Evaporation of the excess water

3 – Sample was transferred to a pre-heated muffle
furnace

4 - Combustion after a few minutes

Resulting material

Samples are pelleted
RESULTS
TL response (a.u.)
QUARTZ

temperature (°C)
High temperature
peak used for dating
RECENT RESEARCHS
250
Pium
Batatal
Natural quartz
sensitized
by heat and gamma
radiation
TL intensity*104 (a.u.)
200
Solonópole
G.Valadares
150
100
50
0
50
100
150
200
250
300
temperature (oC)
(KHOURY et al., Radiation Effects and Defects in Solids, v. 162, pp. 101-107, 2007
350
400
TL GLOW CURVE OF QPS-100 DOSIMETER
IRRADIATED WITH X-RAY
- MAMMOGRAPHY
35
25
(b)
4
Intensidade TL*10 (u.a.)
QPS-100
3,24 mGy
6,48 mGy
9,72 mGy
16,20 mGy
30
20
15
10
5
0
150
200
250
300
350
o
Temperatura ( C)
400
35
QPS-100 (RWX28)
TLD-100 (RWX28)
25
6
Intensidade TL*10 (u.a.)
30
20
15
10
5
0
0
2
4
6
8
10
dose (mGy)
12
14
16
18
HIGH DOSES DOSIMETRY
TL Response of the dosimeter MTS irradiated with gamma radiation of Co-60
H.J. Khoury a,*, B. Obryk b, V.S. Barros a, P.L. Guzzo c, C.G. Ferreira a, P. Bilski b, P. Olko - Radiation
Measurements 46 (2011) 1878e1881
EMISSION SPECTRA MTS
80 kGy
1kGy
TL system for 2-D dosimetry for
radiotherapy
TLD foils
TLD reader with CCD camera
Measured 2-D dose distribution
R. Kopec-SSD-17
Retrospective Dosimetry
Ian Bailif-SSD-17-2013
SEM image: BSE
Ian Bailiff 2013
Construction of thick-film chip resistor
Ian Bailif-SSD-17-2013



►
Investigation of luminescence mechanisms


► Optimum procedure for determining absorbed dose


► Convert dose in chip to dose in air (computational
modeling and phantom irradiation)


► Blind tests with irradiated phones in known gamma
radiation field

► Interlaboratory comparisons (EURODOS group)

Ian Bailiff 2013
FUTURE WORK
Optically Stimulated Luminescence
is a
related
phenomenon
in
which
the
luminescence is stimulated by the absorption
of optical energy rather than thermal energy
OSL- OPTICALLY STIMULATED LUMINESCENCE
OPTICALLY
STIMULATED
LUMINESCENCE
The Conduction Band
E
N
E
R
G
y
100
OSL Intensity
80
Recombination
centre
60
40
The Valence Band
20
0
0
20
40
60
Time (s)
80
100
Modulate the stimulation intensity. Either:
Constant - CW-OSL
or Linear increase - LM-OSL
Stimulation
Power
Stimulation
Power
Time
Time
Photon counts (arb. units)
1.0
0.8
CW-OSL
0.6
0.4
LM-OSL
0.2
0.0
0
2
4
6
8
Time (s)
10
12
14
Pulsed - POSL
……or Pulsed - POSL
Illumination
800
800
POSL
600
600
400
400
POSL
200
200
OSL Detection
0
0
0
500
1000
1500
2000
0
500
1000
Time (ms)
1500
2000
Time (ms)
OSL EQUIPMENT
Landauer
Risø DTU
HOMEMADE READER
GDOIN-DENUFPE
OSL DOSIMETERS
OSL DOSIMETRY
OSL APPLICATIONS

SPACE

MEDICAL

PERSONAL DOSIMETRY

DATING
CHARACTERISTICS OF AL2O3:C OSL
DOSIMETER
SCHEMATIC REPRESENTATION OF THE SETUP USED FOR
IMAGING THE
INFRA-RED STIMULATED LUMINESCENCE
M.R. Baril / Radiation Measurements 38 (2004) 81– 86
RPL- DOSIMETRY

Some kinds of glasses irradiated with the ionizing
radiation show emission of visible photons when excited
by UV light. This phenomenon is usually called the
radio-photoluminescence (RPL).
Formation of RPL Centers
Ag＋＋
Ag+ ＋ e → Ag0 (electron capture)
Ag+ ＋ hPO4 → Ag++ (hole capture)
55
Radiophotoluminescence
Ag activated
Luminescent
phosphate
glass
Glass
UV-light
UV
Luminescent
Center
･・
・･
・ ・
・
・ ・
The silver activated
phosphate glass irradiated
with ionizing radiations emits
luminescence when exposed
to UV light.
This phenomenon is called
RPL.
Radiation
X-ray
Orange Light
Luminescence
Dosimetry with luminescent glass
At present, the most common type of glass in RPL Dosimetry is FD-7.
The AgPO4 in silver activated phosphate glass of FD-7 can be viewed as
Ag+ and PO4
-
Energy Levels of RPL Centers
e-
Conduction band
Ag0
Ex
3.59eV
(345nm)
57
Irｒadiation
Ag+
Blue RPL
2.70eV
(460nm)
PL
4.11eV
(308nm)
5.34eV
(232nm)
Ag ++
4.03eV
(308nm)
Yellow RPL
2.21eV
(560nm)
Valence band
+
h
Energy gained by electrons from the
pulse ultra-violet laser is not high enough
to let electron escape from color centers. Therefore these electrons will not
return to the valence band of the glass material directly.

The luminescence centers never disappear after reading
out the accumulated data by UV light again and over
again. This is the most different characteristic of the RPL
from that of the thermally stimulated luminescence (TSL
or TL) and the optically stimulated luminescence (OSL).
UV off
The most characteristic
features of the glass
dosimeters are data
accumulation and no
fading.
UV on
Low
Absorbed Dose
high
The glass dosimeter always measures the integrated dose, and so if one
wants to know, for example, only today’s exposure dose, one has to subtract
the accumulated dose till yesterday from the total dose observed today.
This is the remarkably different point from TLD and OSLD.
The glass dosimeter does
not utilize the spectrum of
the RPL but observe the
decay curve of the RPL
excited by a short-pulsed UV
laser beam
The decay curve could be
divided into three parts.
The first intensive peak might be attributed
to the PL inherent in the glass and would
decay out within 1μs.
The true RPL signal would decay in 40μs
and
the long decay small signal of the order of
1 ms would correspond to the pre-dose
due to the surface dirt of the glass.
THE CHARACTERISTICS COMPARISONS OF
TLD, OSLD, AND RPL
Thank You