AST / Glass scintillators

Applied Scintillation Technologies.

distributed by

Li doped
glass scintillators

Natural
enriched Li-6 doped ( 95% ⁶Li )
Li-6 depleted ( 99.99% ⁷Li doped )

Lithium Glass Scintillators Physical Properties

	General Description: Applied Scintillation Technologies manufactures a variety of Cerium activated Lithium Glass Scintillators. These have been used for a variety of radiation detection applications since their developed in the 1950s.
	Applications: Typical applications include: thermal neutron detection neutron radiography oil well logging alpha, beta and gamma detection in environments
	Glass types: The glass scintillators are divided into 3 principal types, based on the lithium content (table 1). Each of these is available in natural, ⁶Li enriched or ⁶Li depleted forms. The lithium contents quoted are the initial values of the constitutes of the melt - the content in the finished glass will be slightly lower and will vary. In addition, a special composition ( GSF ) has been developed for mechanical fiber pulling. Compositions at time of melt are given in table 2.
	Glass forms: In addition to fibers, the glass can be supplied as cylinders, rods, discs or plates. Shapes can be provided to customer specification including drilling and polishing and coating with highly reflective paint. Large scintillators ( > 400g ) can be produced as arrays of matched pieces. Glass can also be supplied in powder form with avarage particle size in the range 20µm to 1,000µm.
	Physical properties: Physical properties of the different glass types are shown in table 3.
	Performance characteristics: For detailed performance characteristics, refer other data sheets and cited papers.

**table 1** **Types of Glass Scintillators**
Lithium oxide weight (%)	Natural	⁶Li enriched (95% ⁶Li)	⁶Li depleted (99.99% ⁷Li)
6	GS1	GS2	GS3
6	GSF1	GSF2	GSF3
18	GS10	GS20	GS30
21	KG1	KG2	KG3

**table 2** **Table of Glass Components at Time of Melt**
Component		GS1	GS10	KG1	GSF1
SiO₂	wt%	55	56	74	67
SiO₂	mol%	51	51	63	67
MgO	wt%	24	4
MgO	mol%	33	5
Al₂O₃	wt%	11	18		18
Al₂O₃	mol%	6	10		11
Li₂O	wt%	6	18	21	10
Li₂O	mol%	10	33	36	20
Na₂O	wt%				2.4
Na₂O	mol%				2.4
Ce₂O₃	wt%	4	4	5	2.4
Ce₂O₃	mol%	0.7	0.7	0.8	0.4

**table 3** **Physical properties of Lithium scintillation glass**
	GS1 / 2 / 3	GS10 / 20 / 30	KG1 / 2 / 3	GSF1
Density ( g / ml )	2.66	2.50	2.42	2.42
Reflactive index: n	1.06	1.55	1.57	1.58
Glass Transition: Tg ( °C )	620	499	464	610
Softening point: Ts ( °C )	650	522	490
Strain point: Tsr ( °C )	350	410	461	386
Coefficient of Linear expansion	7.0 x 10 ^-6	9.23 x 10 ^-6	100 x 10 ^-6
max emission wavelength ( nm )	395	395	395	395
Relative light pulse height per unit	100 ^{[ 1 ] [ 2 ]}	85 ^{[ 2 ]}	60 ^{[ 2 ]}	80
Relative light output to Anthracene	22% ~ 34%	20% ~ 30%	20%
Decay time ( nSec )	50 ~ 70	50 ~ 70	50 ~ 70	50 ~ 70
Resolution on the thermal neutron peak obtained with moderated Po/Be neutrons ^{[ 3 ]}	13% ~ 22% ( GS2 )	13% ~ 22% ( GS2 )	20% ~ 30% ( KG2 )
Peak / through ratio of above peak ( range ) for thermal neutrons	15:1 ~ 40:1 ( GS2 )		10:1 ~ 20:1 ( KG2 )
[1] pulse height of GS1 is 15% to NaI(Tl) [2] determined by thickness / light output raises by decreasing thickness down to ~ 2mm [2] thermal neutron resolution depends on system geometry

References:

L. A. Wraight	Nucl. Inst. & Meth.	33, 181 - 193	(1965)
A. Spowart	Nucl. Inst. & Meth.	75, 35 -42	(1969)
M. S. Coates	AERE-PR/NP11 33,	181 - 193	(1967)
J. Cameron	Nucl. Inst. & Meth.	56, 45 - 54	(1967)
H. Zetterstrom	Nucl. Inst. & Meth.	42, 277 - 282	(1966)
E. Fort	Nucl. Inst. & Meth.	85, 115 - 123	(1970)
A. Spowart	Nucl. Inst. & Meth.	82, 1 - 6	(1965)
A. Spowart	Nucl. Inst. & Meth.	140, 19 - 28	(1965)

Lithium Glass Scintillators neutron detection

General:
Applied Scintillation Technologies manufactures a variety of Cerium activated
Lithium glass scintillators. These have been used for a variety of radiation
detection applications since their development in the late 1950s.

The glass scintillators are extremely robust being resistant to all organic and
inorganic chemicals except hydrofluoric acid and strong alkalis and can be used
in temperatures ranging from -200°C to 250°C. This allows them to be used in
conditions which prohibit the use of other scintillation materials.

Neutron detection:
The 3 types of glass available are natural lithium base, ⁶Li enriched and
⁶Li depleted. The properties of the 3 types are similar except for neutron
detection where the 6Li enriched glasses are better.

The detection mechanism is,
n + ⁶Li > Triton + + ~ 4.8MeV

Details of excitation are emission are shown in following graph.

Graph showing excitation and emission spetrum of Ce³⁺ in Li glass

table 4        neutron detection capabilities
neutron energy glass type glass thickness

0.01 ~ 20eV all types 0.1 ~ 10mm

thermal GS20 1.3mm

10eV ~ 100keV GS20 3.2mm

100eV ~ 1MeV GS20 25.4mm

1keV ~ 600keV KG2, GS20 9.5mm

1MeV ~ 6MeV GS20 25mm

Selectivity

Using pairs of ⁶Li and ⁷Li glasses, the gamma background detected can be subtracted.
The GS20 glass is particulary selective in its detection of thermal neutrons as shown by following graph. This shows the pulse height spectrum for GS20 glass with an example background from ⁶⁰Co.
Table 5 also shows an additional information on neutron selectivity overgamma response.


table 5        Gamma sensitivities
   scintillator type
   and thickness Gamma photons to give the
same light output as 1 neutron measured Gamma **
attenuation coefficient

²²⁶Ra ¹³⁷Cs ⁶⁰Co ²²⁶Ra ¹³⁷Cs ⁶⁰Co

   GS20; 1mm ^t 850 240 100 3.06 3.16 1.63

   GS20; 1.5mm ^t 550 160 74 8.14 7.89 2.17

   GS20; 3mm ^t 390 100 50 17.5 23.16 5.43

   KG2L; 6.2mm ^t 310 81 57 37.8 33.69 25.

  ** note:
     Gamma attenuation coefficients are underestimated due to detection of degraded Compton photons.
     The error will be greatest for 1mm thick glass and smaller for thicker samples.

Applied Scintillation Technologies
8 Roydonbury Industrial Estate,
Harlow CM19 5BZ,    United Kingdom
Phone# +44 (0)1279 641 234    Fax# +44 (0)1279 413 679

Local distributor in Japan
APACE Science, Inc.
Mitomo-Bldg.#2 - 6F, Ebisu-nishi 2-Chome
Shibuya-Ku, Tokyo 150-0021
Phone# +81-(0)3-3463-3204    Fax# +81-(0)3-3463-3205

  |   PageTop   |   Applied Scintillation Technologies TopPage   |

  |   AST Phospohors Page   |   APACE TopPage   |

	Graph showing excitation and emission spetrum of Ce³⁺ in Li glass

neutron energy	glass type	glass thickness
0.01 ~ 20eV	all types	0.1 ~ 10mm
thermal	GS20	1.3mm
10eV ~ 100keV	GS20	3.2mm
100eV ~ 1MeV	GS20	25.4mm
1keV ~ 600keV	KG2, GS20	9.5mm
1MeV ~ 6MeV	GS20	25mm

scintillator type and thickness	Gamma photons to give the same light output as 1 neutron			measured Gamma attenuation coefficient**
	²²⁶Ra	¹³⁷Cs	⁶⁰Co	²²⁶Ra	¹³⁷Cs	⁶⁰Co
GS20; 1mm ^t	850	240	100	3.06	3.16	1.63
GS20; 1.5mm ^t	550	160	74	8.14	7.89	2.17
GS20; 3mm ^t	390	100	50	17.5	23.16	5.43
KG2L; 6.2mm ^t	310	81	57	37.8	33.69	25.
** note: Gamma attenuation coefficients are underestimated due to detection of degraded Compton photons. The error will be greatest for 1mm thick glass and smaller for thicker samples.

	Applied Scintillation Technologies 8 Roydonbury Industrial Estate, Harlow CM19 5BZ, United Kingdom Phone# +44 (0)1279 641 234 Fax# +44 (0)1279 413 679
Local distributor in Japan	APACE Science, Inc. Mitomo-Bldg.#2 - 6F, Ebisu-nishi 2-Chome Shibuya-Ku, Tokyo 150-0021 Phone# +81-(0)3-3463-3204 Fax# +81-(0)3-3463-3205

	\| PageTop \| Applied Scintillation Technologies TopPage \|
	\| AST Phospohors Page \| APACE TopPage \|