1 - IAEA Nuclear Data Services

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of alpha particles in the reaction 2 %g( 3 He,a) 2 5Mg, in the
energy range of the incoming ^He 4*6 MeV, using the 6 MeV
Van de Graaff of Frankfurt am Main University. A diffractional
model has been derived by using complex angular momenta methods
which fit the experimental data extremely well.pioj.
Work is under way to ascertain the limits of validity for such
a model.
1.7» Analysis of nuclear reactions with the 2 9si as intermediate
system Ç5J
The statistical fluctuations in the excitation functions of
some nuclear reactions ( 2 7Al+d, 2 ^si+n, 2 ^Mg+^He) having the
2 $si as intermediate system, have been analyzed in order to
estimate the values of D0 = Dj(2j+1) and r of the C.N. levels.
It is shown that these quantities are simply related by
2 D
X o
< a ft >- 2(21+1 )(2Í+1) TR
' o
where< ap > is the average fluctuating cross section and R
the normalized variance of the fluctuations.
The obtained values of D and r agree with theoretical predictions
based on the Fermi gas nuclear model.
1.8. The ?Li+d reactions
Measurements of bidimensional spectra and angular correlations
between the two alpha particles are in progress. The alpha
particles from the ?Iii+d-»a + a+n are detected by means o£ solid
state detectors and pulses analyzed by a 4096 channels LABEN
analyzer.
Preliminary results were given at the 53rd meeting of the
Italian Society of Physics [6^« These results allowed to give
an estimate of the three body direct break-up in the reaction.