The Scintillation Mechanism In Gd Based Crystals Doped With Re 3+ Ions.
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of Nuclear
IONS.
V.B.Pavlenko.
M.V.Korzhik,
D.M.Kondratiev, Institute
Gd BASED CRYSTALS DOPED WITH
IN
THE SCINTILLATION MECHANISM
220080
Minsk
ii,
Bobruikaya
Problems,
Belarus ABSTRACT crystals on the base
in
The mechanism of scintillations
of
Gd3+ - Ce3+ transfer have been developed. INTRODUCTION In
the work
arise in
[1) dedicated
scintillators
NaI(Tl) role
in
analogy
the
However,
process
changes
Gd-containing
in
the
well-known
excitation
process is
This
ions
mechanism ignores
matrix forming
the
crystals.
this
of
Meanwhile the presence of Gd sufficient
with
the recombination mechanism of Ce3+
luminescence was proposed. matrix
to the process of scintillations
Gd2SiO 5 :Ce crystals on
of
ions
energy
caused
by
Gd 3+ions form inside of the forbidden zone
the
localization. gives
the
two
the
exchange fact
in that
narrow
(6E
states 0.5eV) subzones. The subzones are caused by the energy 6 and 01 with the energies relative to the basic state S 3+
Gd
.-
i
ions near E
32000
and
36000 sm
E 33+
When Gd 2SiO5 crystals are activated transitions
energies of Ce3
mentioned subzones [2]. transfer from activation
Gd
close
Ce
to
energies
the
ions
,
which
are
donors
agreement
-
d the
energy to
the
ions due to multipole interactions. investigated
data and discussions
Ce-doped
gadolinium
Gd SiO :Ce (GSO:Ce) were grown by the Czochralski 2 5 Their spectroscopic and the iridium crucible. parameters
f of
This fact assumes the intensive
matrix
Experimental The
are
respectively.
by
are given in with the results
works [3,23.
orthosilicate method scintillator
The received data
of other authors
from
[4,5].
411 Mat. Res. Soc. Symp. Proc. Vol. 348. 01994 Materials Research Society
are
in
Gd In the Gd SiO 5:Ce structure the Ce ions replacing the numbers 7 with coordination ions are stabilized in two sites and 9,
in
ninth coordination E3).
case basically in
this
but the luminescence
GSO crystals,
kinetics is
by migration
processes.
practically quenched.
In
bands of
are
3+
Gd
ions
Gd
in
ions
Ce-doped
spectra
excitation
crystals Ce3+ions
of
is the
that the Gd3+ by
it shows So, observed. Ce3+ ions luminescence of
sensitization
effective
quenched
3+.
of
The luminescence
pure
one exponential
that luminescence
= 5 ps. This fact justifies
with T
the
in
strong quenched
The luminescence 6P - aS is
occurs. the
Under kinetics
practically
excitation
photo one
remains
the
with
unchanged
the
Ce +ions
with
exponential
T
luminescence 23
=
changing
and
ns
the
of
activator
that it appears However, mole%. I n up to concentration on light greatly depend kinetics Ce +ions luminescence Ce3+ of excitation The (Fig.1). frequency excitation luminescence the decay
bands (curve 2)
thought Gd+
time of Ce3+
the
caused
kinetics.
luminescence
increase this
Moreover
kinetics close to the kinetics of GSO:Ce scintillators. localization of excitation on Ce 3+ions 3+ 3+ it is possible . So, caused
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