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Submitted on 1 Jan 1979
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THE DEPENDENCE OF FILTERED RESONANCE RADIATION OF 119Sn
N. Hayashi, I. Sakamoto
To cite this version:
N. Hayashi, I. Sakamoto. THE DEPENDENCE OF FILTERED RESONANCE RADIATION OF 119Sn. Journal de Physique Colloques, 1979, 40 (C2), pp.C2-53-C2-54. �10.1051/jphyscol:1979219�.
�jpa-00218567�
JOURNAL DE PHYSIQUE
Collogue C2, supplement au n" 3, Tome 40, mars 1979, page C2-53
THE DEPENDENCE OF FILTERED RESONANCE RADIATION OF
l l yS n
N. Hayashi and I. Sakamoto
Eleetroteehnioal Laboratory, Mukodai, Tanashi, Tokyo, Japan
Résumé.- Nous avons mesuré la dépendance en temps des rayons y filtrés par la résonance à 23,9 keV de 1 1 9Sn par la méthode des coïncidences retardées. Des oscillations caractéristiques ont été obser- vées dans la distribution en temps du rayonnement transmis. L'accord quantitatif entre les courbes expérimentales de la décroissance et les prédictions théoriques a été obtenu.
Abstract.- The time dependence of resonantly filtered 23.9 keV 1 1 9Sn y-rays was measured by means of delayed coincidence techniques. Characteristic oscillations in the time distribution of the trans- mitted radiation through absorbers have been observed. Quantitative agreement between experimental decay curves and theoretical predictions has been obtained.
The technique of coincidence Mossbauer spec- troscopy (CMS) is a powerful method to study certain time dependent processes occuring at a time scale comparable to the life time of the Mossbauer state.
The technique has been applied to the studies of solid state physics /l/. Some works have been done to apply the technique to 1 1 9Sn using 26 keV X-ray - 23.9 keV y-ray coincidence /2-3/. Very few quantita- tive analyses of the spectra obtained by CMS, however, have been done in the case of 1 1 9Sn. It is extremely useful if the transmitted Y-ray intensity be measu- red explicitely as a function of time. The results of such a measurement are described in this report.
In the measurement interference effects due to coherent resonance excitation can be observed in the time distribution of the transmitted radiation, and "time filtering" effects result in non-exponen- tial decay curve. The equations of the transmitted intensity through a resonant filter (absorber) can be written in two forms depending on the time region of interest /4/
00 n — 2
I(v,T,B)= e_ T I (4i|) (^-)2 Jn(/B?) , l n=o
for 2v(BT)5 /B <1, and
co n -n I(v,T,B)= e"T exp{i(vT+i)} - I (i~) (^) Jj/BT)
l n=l for 2v(BT)2 /B > 1.
Here v is the energy difference between incident radiation and absorber response in units of natural linewidth (r), J 's are integral Bessel function, T
n
is time in nuclear meanlife (T) units, and B = naQf is the absorber thickness.
The experimental system was a standard dela- yed coincidence arrangement with a Mossbauer instru-
ment in addition. The 26 keV X-ray from the highly converted M4 transition which populated the 23.9 keV level in 1 1 9Sn served as a start and the 23.9 keV y-ray as a stop signal to a time to amplitude conver-
ter. RCA 8850 and RCA 8575 photomultipliers with thin Nal(TL) crystals were used to detect the 23.9 keV y-ray and 26 keV X-ray, respectively. The time reso- lution was estimated to be about 5ns. A CaSn03 source of 2uCi was mounted on a velocity drive which was used to shift the resonance frequency of the incident radiation. CaSnO absorbers (2.0 mg/cm2 and O.Smg/cm2) were used as resonant filters with a Pd foil.
Some examples of experimental results are shown in figures 1-3 where v and B are changed as experimental parameters. The broken curves are the decay curves which were obtained in the measurements with no absorber. The solid curves were calculated from the theoretical equations above mentioned.
The quantitative agreement between theory and experiments is satisfactory as shown in the figures.
In the calculation the values of recoilless fraction were changed as an adjustable parameter; it has been described in our previous manuscript /5/ that recoil- less fraction can be obtained by fitting theoretical curves to experimental data. The fitting of figures 1-3 has been performed with a value of 0.53 for the recoilless fractions of both CaSn03 source and ab- sorbers. It may be possible by these measurement that time-dependent recoilless fraction could be directly measured at a life time scale.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1979219
JOURNAL DE PHYSIQUE
0 1 2 3 4 5
t i m e ( t l r )
Fig. 1 : Time dependence of the gamma-rays transmit- ted through the resonant CaSnO, absorber (2.0mg/cm2 of l19sn) with energy shift of v = 0.
to'
-
0 1 t i r n e ( t I T ) 2 3Fig. 2 : Time dependence of the gamma-rays transmit- ted through the resonant CaSnO, absorber (0.5mg/cm2 of '19sn) with energy shift of v = 0.
References
/ I / Triftshauser, W. and Craig, P.P., Phys. Rev.
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(1967) 274.
/2/ Carmeliet, J. and Lejeune, S., Nucl. Instrum.
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(1970) 93./3/ Dehaes, J.C., J. Physique Colloq. _?1 (1974) C1- 77.
/4/ Lynch, F.J., Holland, R.E. and Hamermesh, M., Phys. Rev.
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(1960) 513./5/ Hayashi, N., Kinoshita, T., Sakamoto, I. and Furubayashi, B., Nucl. Instrum. Methods
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(1976) 317.
/6/ Hoy, G.R. and Wintersteiner, P.P., Phys. Rev.
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(1972) 877./7/ Gupta, A. and Reddy, K.R., Solid State Commun.
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-
Fig. 3 : Time dependence of the gamma-rays transmit- ted through the resonant CaSnO, absorber (0.5mg/cm2 of l19sn) with energy shift of v = 2r.
