Inexpensive, commonly used NaI:TI scintillators have 50% of the market share, but due to mediocre light output of 44,000 photons/MeV and 6.5% energy resolution (at 662 keV) their application is limited. Proposed technology promises to improve NaI:TI-based scintillators' properties by providing unparalleled output while maintaining low costs. To do so a combinatorial approach was used for the discovery of scintillation materials yielding the highest luminescence and lowest energy resolution. In testing, the engineered crystals of NaI:Tl attained a light output of 52,000 photons/MeV and energy resolution of 4.9% (at 662 keV). Crossing below the 5.0% energy resolution mark provides a specific direction for the development of even better future samples. Talk was presented by I.V.Khodyuk and SCINT15

1. 1Ivan Khodyuk – SCINT15
Improvement of NaI:Tl light output
and energy resolution by co-doping
I.V. Khodyuk, S. Messina, T. Hayden, S.E. Derenzo, E.D. Bourret, G. A. Bizarri
Lawrence
Berkeley
Na.onal
Laboratory,
Berkeley,
CA
-­‐
USA

2. 2Ivan Khodyuk – SCINT15
NaI
–
Performance
Engineering
Factor Level 1 Level 2 Level 3 Level 4
Dopant Tl - - -
[Dopant], % 0.0 0.1 0.25 0.5
Co-dopant Mg Ca Sr Ba
[co-dopant] 0.1 0.2 0.4 0.8
[Eu2+], % 1.0 0.5 0.1 0.0
Sequential trial of different compositions – 256 crystals
Design of Experiment using L16 orthogonal array – 16 crystals
Goal: Improvement of NaI Light Output and Energy Resolution by co-doping
Benchmark: NaI:Tl – 44,000 ph/MeV and 6.3% at 662 keV
Factorial (parametric) space to discover:
Best value reported - Shiran et al.: NaI:Tl,Eu – 48,000 ph/MeV and 6.2% at 662 keV

3. 3Ivan Khodyuk – SCINT15
Design of Experiment
-XRD
-OE
-XRL
-PXR
-XRF
Response to
Gammas
-PHM
Non-proportionality in house and at the ALS
Advanced characterization: -TSL, -OSL, -Afterglow, -ICP/GDMS
Powder
chemistry &
melt-mix crystal
synthesis
mm-size
crystals
processing
Single crystal
growth
cm-size crystals
processing
Phase I Phase II
Design
of
Experiment
+
HTCF
Multi-regressiondataanalysis
Selected samples
HighThroughputCharacterizationFacility

4. 4Ivan Khodyuk – SCINT15
Design
of
Experiment
# [Tl+] Co-d [co-d] [Eu2+] ER,% LO, ph/
KeV
0 0.1 - 0.0 0.0 7.0 43
1 0.0 Mg 0.1 1.0 8.5 24.6
2 0.0 Ca 0.2 0.5 6.4 37.3
3 0.0 Sr 0.4 0.1 9.9 14.5
4 0.0 Ba 0.8 0.0 21 5.1
5 0.1 Mg 0.2 0.0 13.4 18.3
6 0.1 Ca 0.1 0.1 6.9 41.6
7 0.1 Sr 0.8 0.5 8 35.5
8 0.1 Ba 0.4 1.0 13.1 4.1
9 0.25 Mg 0.4 0.5 20 12.4
10 0.25 Ca 0.8 1.0 7 33.9
11 0.25 Sr 0.1 0.0 6.1 29.9
12 0.25 Ba 0.2 0.1 5.9 47
13 0.5 Mg 0.8 0.1 17.5 33.4
14 0.5 Ca 0.4 0.0 10.9 22.6
15 0.5 Sr 0.2 1.0 12 23.8
16 0.5 Ba 0.1 0.0 17.5 16.7
Fractional factorial design using L16 orthogonal array
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0
5
10
15
20
H omemade
reference
C ommercial
reference
Energy
Resolution
@
662keV
(%)
D es ign
number
Mg
C a
S r
B a
B aMg
C a S r
B a
Mg
C a
S r
B aMg
C a
S r
S tatistical
limit
for
44000
photons/MeV
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0
5
10
15
20
25
30
35
40
45
50
H omemade
reference
Light
Output
(photons/keV)
D es ign
number
Mg
C a
S r
B a
Mg
C a
S r
B a
Mg
C a
B a
S r
Mg
C a
B a
S r
C ommercial
reference

5. 5Ivan Khodyuk – SCINT15
Experimental
design
output
-­‐
visualizaAon
Performance (ER) optimization in 4 dimensional parametric space

6. 6Ivan Khodyuk – SCINT15
OpAmum
composiAon
synthesis
(melt-­‐mix)
0 1000 2000 3000 4000 5000
0
100
200
300
400
Counts
P MT 1
C hannel
S 4
L Y
=
46200
ph/MeV *
E R
=
5.4%
*LO corrected for PMT QE
Multi-regression analysis
Optimal composition
Factor Level 1 Level 2 Level 3 Level 4
[Tl+] 0.0 0.1 0.25 0.5
Co-dopant Mg Ca Sr Ba
[co-dopant] 0.1 0.2 0.4 0.8
[Eu2+] 1.0 0.5 0.1 0
NaI: 0.25%Tl, 0.1%Eu, 0.2%Ca
Quick optimal composition synthesis
and performance evaluation

7. 7Ivan Khodyuk – SCINT15
OpAmum
composiAon
synthesis
(Bridgman)
NaI: 0.25%Tl+, 0.1%Eu2+, 0.2%Ca2+ – nominal concentrations in the melt
Part of boule [Tl+],
ppm wt
[Ca2+],
ppm wt
[Eu2+],
ppm wt
nominal in melt 3470 540 1000
top 14641 580 890
center 1500 490 940
bottom 880 580 940
Inductively Coupled Plasma Mass
Spectrometry (ICP-MS) results:
Conclusions: 1) Significant Tl segregation during the Bridgman growth;
2) Parts of the crystal with lower [Tl+] show better ER and LO
42 43 44 45 46 47 48 49 50 51 52
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
top
center
bottom
Energy
Resolution
@
662keV
(%)
L ight
O utput
(photons /keV )
5.2%
(51.1ph/keV )
S tatis tical
limit
for
44000
photons /MeV
R eference
NaI:T l
#0
C ommercial
NaI:T l

8. 8Ivan Khodyuk – SCINT15
NaI:TEC
–
OpAmum
composiAon
(Bridgman)
NaI with lower concentration of Tl+ – 0.1 mole % in the melt was grown
using same Bridgman furnace
550 600 650 700
0.0
0.2
0.4
0.6
0.8
1.0
1.2
Normalized
counts
G amma
energy
(keV )
NaI:T l
commercial
reference
-­‐
6.3±0.2%
NaI:T l,C a,E u
co-­‐doped
-­‐
4.9±0.2%
52000 ph/MeV
4.9% at 662keV
NaI:TEC (Tl, Eu, Ca) – with 52,000 ph/MeV and 4.9% resolution at 662 keV

9. 9Ivan Khodyuk – SCINT15
NaI:Tl
vs
NaI:TEC
characterizaAon
(i)
250 300 350 400 450 500 550 600 650
NaI:T E C
NaI:T l
reference
XRL
emission
intensity,
arb.
un.
W avelength,
nm
0 1000 2000 3000 4000 5000
NaI:T l
reference
NaI:T E C
Counts/bin
T ime
(ns )
NaI:T l
-­‐
195
ns
NaI:T l,
E u,
C a
-­‐
195
ns
(20% )
1790
ns
(80% )
X-ray luminescence Scintillation decay time
XRL emission max at 450nm 80% of the light emitted through
“long” 1.8µs component

10. 10Ivan Khodyuk – SCINT15
NaI:TEC
characterizaAon
(ii)
NaI:Tl reference NaI:TEC

11. 11Ivan Khodyuk – SCINT15
NaI:TEC
characterizaAon
(ii)
6s à 6p
4f à 5d
Tl+
Eu2+
[Eu2++Vac]
Tl+

12. 12Ivan Khodyuk – SCINT15
NaI:Tl
vs
NaI:TEC
characterizaAon
(iii)
- Non-proportionality was
measured at the ALS (LBNL)
using micro-tomography
beamline
- Systematic change of
Photon-nPR curve at
6-60keV enregy range
Photon non-proportional response
Early stages of scintillation process are affected bythe co-doping of NaI:Tl
NaI:Tl LO 44ph/keV à ER 6.3%
NaI:TEC LO 52ph/keV à ER 5.9%
à ER 4.9%

13. 13Ivan Khodyuk – SCINT15
Conclusion
• Design of experiment (fractional factorial design) has been
used to speed up discovery of Eu2+ and IIA influence on
scintillation performance of NaI:Tl and will be applied to
other materials and factors
• Optimal composition – NaI:TEC (0.1%Tl+, 0.1%Eu2+,
0.2%Ca2+) determined with multi-regression analysis gives
52000 photons/MeV and 4.9% grown by Bridgman
• NaI:TEC under X-rays and optical excitation is emitting light
predominantly through Eu2++Vac cluster with max at 450nm
and main decay component of 1.8µs

14. 14Ivan Khodyuk – SCINT15
Acknowledgements
The authors would like to thank S. Hanrahan, D. Wilson, and Dr. J. Powell for
their technical and engineering support and Drs. G. Gundiah, M. Gascon,
E. Samulon, D. Perrodin and T. Shalapska for their scientific input.
Combinatorial and high throughput material synthesis part of this work was
supported by the US Department of Homeland Security/DNDO and crystal
growth effort by the US Department of Energy/NNSA/DNN R&D and carried
out at Lawrence Berkeley National Laboratory under Contract no.
AC02-05CH11231. This work does not constitute an express or implied
endorsement on the part of the government.