Emission of light charged particles in the reactions of 120 MeV 20Ne with 27Al

The emission of H and He isotopes in the reactions of 120 MeV ²⁰Ne with ²⁷A1 has been studied using light particle-heavy ion coincidence measurements. The energy spectra and angular correlations of the light particles emitted in coincidence with products of $\text{Z ≧ 14}$ agree well with the predictions of the statistical model applied to the decay of the compound nucleus ⁴⁷V. Results on α-particle emission associated with deep inelastic reactions leading to carbon and oxygen products are also reported.     

Nucleon transfer calculation in reactions induced by12C to22Ne ions

A classical-statistical model is presented here in order to predict the isotopic production in light heavy ion reactions. The dynamical approach includes a nucleon exchange term. Such transfer is made possible through a window and a simple gas theory argument. The distribution of the cross section among all the allowed exit channels is then calculated within the statistical assumption. Excellent agreement is obtained with light heavy ion experimental cross section. The neck configuration is shown to be in reasonable agreement with the one deduced from Nix's liquid drop model.     

Continuous proton spectra emitted in 3He and deuteron induced reactions

A study of the energy and angular distributions of protons emitted in ³He induced reactions was undertaken at an incident energy of 25.6 MeV. An analysis in the framework of the pre-equilibrium hybrid model did not succeed in explaining the overall behaviour of proton spectra; a contribution due to a break-up or a double stripping of the incident particle has to be taken into account. An attempt was made to account for these processes by performing a phase space calculation. This formulation was firstly tried in the case of deuteron induced reactions for which a break-up mechanism has already been confirmed in continuous proton spectra. The calculation extended to the case of ³He induced reactions showed that a double stripping mechanism could explain the observed distribution.     

Recursively enumerable sets of polynomials over a finite field are Diophantine

We construct a Diophantine interpretation of over . Using this together with a previous result that every recursively enumerable (r.e.) relation over is Diophantine over , we will prove that every r.e. relation over is Diophantine over . We will also look at recursive infinite base fields , algebraic over . It turns out that the Diophantine relations over are exactly the relations which are r.e. for every recursive presentation.     

Prompt light particle emission in the 36Ar + 58Ni reaction at 95 MeV/nucleon

The prompt component at intermediate velocity of light charged particles is investigated. An improved coalescence model coupled to the intra-nuclear cascade code ISABEL is used to obtain light complex particle energy spectra and multiplicities as a function of impact parameter. The results are compared with experimental data from the ³⁶Ar + ⁵⁸Ni experiment at 95 MeV/nucleon, performed with the INDRA 4π detection system. The calculated prompt component is found to rather well reproduce proton spectra. For complex light charged particles the calculated components well populate the high energy part of spectra. Prompt emission can therefore explain the large transverse energies experimentally observed at mid-rapidity. Received: 27 July 2000 / Accepted: 20 November 2000     

II. The intermediate velocity source in the 40Ca + 40Ca reaction at Elab = 35AMeV

The shape of the velocity distributions of charged particles projected on the beam direction can be explained if emissions from the hot projectile-like fragment and the target-like fragment are supplemented by an emission from an intermediate velocity source located between them. The creation of this source is predicted by a two-stage reaction model where, in the second stage, some of the nucleons identified in the first stage as participants form a group of clusters located in the region between the colliding nuclei. The cluster coalescence process is governed on the average by the maximum value of entropy, although its fluctuations are also significant. The properties of the intermediate velocity source are precisely described, including the isotopic composition of the emitted particles. Received: 12 March 2001 / Accepted: 20 June 2001     

Charge partition probabilities in the 32S + 27Al reaction at 37.5 MeV/nucleon analysed using the Boltzmann distribution

We apply the Boltzmann distribution to charge partition probabilities measured with the AMPHORA multidetector in the reaction ³²S + ²⁷Al at 37.5 MeV/ nucleon. Approximate corrections to the data for pre-equilibrium emission are made and modifications to the basic formalism due to detection e?ciency and evaporation are treated explicitly. The data are well reproduced with a temperature of 5.0 MeV and a freeze-out volume which corresponds to densities which are 20 times smaller than normal density.     

An Existential Divisibility Lemma for Global Fields

We generalize the Existential Divisibility Lemma by Th. Pheidas [7] to all global fields K of characteristic not 2, and for all sets of primes that are inert in a quadratic extension L of K. We also remove the conditions in real and ramifying primes, which were present in Pheidas’ version. As a Corollary, we recover the known fact that the set of integral elements at a prime in a global field is existentially definable.     

The third particle in deep inelastic collisions

Angular correlations between charged reaction products have been measured for the reaction¹⁴N+²⁷A1 at 70 and 100 MeV. Light particle evaporation from the heavy recoil is shown to be the dominant process. In addition, however fast alphas are observed for all reaction channels. From the three-body kinematics we conclude that these alphas are emitted from the contact zone between the two heavy ions. A comparison of the results forE _Lab=70 and 100 MeV excludes an explanation of this process by the recently suggested “Piston” or “hot-spot” models.