α Emission in proton induced reactions

An evaluation of alpha particle clustering in heavy nuclei

“…and assuming the value of 3.6 clusters, the 4) value of 0.1 valid at energies greater than 50 MeV increases slowly to 0.18 at 30 MeV and 0.41 at 10 MeV in excellent agreement with the suggestion in Ferrero et al [33] of a value of 4)=0.19 for alpha spectra arising from a wide variety of targets at energies from 30-55MeV, and with the values of MeV [23]. It is gratifying to find that this previously unexplainable inconsistency in Exciton model calculations is resolved by the present work.…”

“…Calculation of the nucleon-alpha interaction rate is considerably more complex. The form of the double differential cross section for the N-c~ scatter was obtained by fitting experimental data to equations of form [33] d2o -…”

The mechanism of the (p, ?) reaction: Pick-up or knock-out?

“…The exciton model calculations assumed the presence of pre-existing alpha-particles in the nucleus which are then knocked out by the incident protons. This enabled a good overall account of the spectra and the angular distributions of the alpha-particles to be obtained for a series of nuclei from 93Nb to 169Tm at incident proton energies from 20 to 45MeV [17,18]. The multistep direct reaction calculations of Tamura and Udagawa [-19] used the triton-pickup mechanism, and again found satisfactory agreement with the experimental data.…”

“…The question of the mechanism of the (p, c~) reaction is also important for studies of the continuous spectrum of alpha-particles emitted when high energy protons interact with nuclei. Several studies of such reactions have been made using the quasi free scattering model [-16] the exciton model [17,18] and the multistep direct reaction theory [19,20]. The exciton model calculations assumed the presence of pre-existing alpha-particles in the nucleus which are then knocked out by the incident protons.…”

Charged-particle cross section database for medical radioisotope production: chapter 3. theoretical evaluations

“…For the preequilibrium nucleon emission the geometry dependent hybrid (GDH) model is used. Calculation of the alpha-particle spectra is performed taking into account both the pickup (Iwamoto and Harada, 1982;Sato et al, 1983) and knockout processes (Milazzo-Colli and BragaMarcazzan, 1973;Ferrero et al, 1979;Oblozinsky and Ribansky, 1978). A phenomenological approach is used to describe direct emission of the deuteron (Dityuk et al, 1998).…”