1 - IAEA Nuclear Data Services
1 - IAEA Nuclear Data Services
1 - IAEA Nuclear Data Services
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
- 97•-,<br />
XVI. GRUPPO DI RICERCA DEL CONTRATTO EURATOM-CNEN-IÑFN - ISTITUTO<br />
DI FÍSICA DELL'UNIVERSITA', PAVIA (ITALY)<br />
1.1. The Low Energy Group of the <strong>Nuclear</strong> Physics Institute of the<br />
University of Pavia has begun the study of the emission of<br />
long-range alpha-particles and light nuclei during nuclear<br />
fission, in order to achieve more detailed and accurate inform<br />
ation about the fission problem and the nuclear matter in<br />
general [1], [2], [3], [4], [ 5~]. In this year, it has been<br />
measured the energy spectrum of the alpha-particles and identi<br />
fied the helium isotopes from thermal neutron induced fission<br />
of 2 3%u, using a neutron beam extracted from the Triga Mark II<br />
reactor of the University of Pavia.<br />
In order to identify the various light charged particles, a<br />
DE-E solid state telescope, allowing simultaneous determination<br />
of- the total kinetic energy and energy loss of the incident.<br />
particles, has been employed [6].<br />
The energy spectrum of the 11.300 detected long-range alpha-<br />
-particles above 13 MeVJ corrected for loss in the Nickel<br />
absorber, is shown in fig. 1.<br />
The gaussian curve has its maximum at 16 MeV and a 4,66 MeV<br />
HVHM. The peak energy is slightly less than reported in the<br />
only 2 3%>u experiment known to us which was performed by Perfi-<br />
lov and coll. \_1~\ with very poor statistics.<br />
The He isotopes recorded are the following [8J:<br />
- 47 events of "He with energy above 17 MeV giving an intensity<br />
of 0,4 relative to emission of 100 alpha-particles<br />
- 42 events attributable to ^He above 12 MeV with a yield rela<br />
tive to emission of alpha-particles of 2.6.10~3<br />
- 7 events attributable to 8He.