L. Bracci

Atomic effects in the determination of nuclear cross sections of astrophysical interest

Abstract We discuss the relevance of electron screening on nuclear reactions between ions and neutral atoms from a few to a few-hundred keV. We present a general method of calculation of the atomic effects and discuss quantitatively the limiting cases of low and high velocity of the nuclei as compared to typical electron velocities. Results for several low-energy fusion reactions and proton capture processes are presented and recent experimental data on the d 3 He reaction are discussed. Concerning this latter reaction, the reported rise of the astrophysical factor at keV energies cannot be explained in terms of electron screening and should be connected with a nuclear-structure effect.

Some aspects of the muon catalysis of d-t fusion

Abstract When a deuteron, a triton and a muon are bound in a (dμt) mesomolecule the nuclear reaction d + t → 4 He + n takes place in a very short time. In this paper the processes following the nuclear reaction are studied. The probability of the muon sticking to the α-particle is found to be w = (1.2 ± 0.1) × 10 −2 . All the processes which can strip the (μα) during the slowing down are taken into account. At the end of the slowing down the probability for the muon still to be bound to the α- particle is

Formation of monopole-proton bound states in the hot universe

w = 9.1 × 10 −3 . Consequently the maximum number of d-t fusions one muon can catalyse is N max = 1 w = 110 . The yields of K and L (μα) lines are also calculated: K = 0.60 × 10 −2 , L = 0.59×10 −3 .

Bounds on a hypothetical fundamental length

Abstract We discuss the kinetics of formation and dissociation of (Mp) bound states in the hot universe. We find that at the end of this era most likely monopoles are bound to protons. We discuss the relevance of this effect on the detection of magnetic monopoles.

On the energy loss of very-slowly-moving magnetic monopoles

Abstract We derive bounds for the fundamental length l 0 of T.D. Lees discrete quantum mechanics by analysing low energy physics measurements: nuclear radii, Lamb shift and hyperfine structure of the hydrogen atom. This last yields the most stringent bound, l 0 ⩽ 3 × 10 −5 fermi.

Monopole Trapping Inside Stars and Phenomenological Consequences

Abstract We investigate the energy loss of magnetic monopoles with β ⪅10−4, arising from elastic collisions with hydrogen and helium atoms. At liquid hydrogen density, we find d E d x ∼ 50 MeV/cm . We discuss the relevance of this result for monopole searches. We find that monopoles with β ⩽10−4 are stopped by the earth and by the moon, and we derive a bound on monopole flux: φ ⪅ 10−4 (m2 day sr)−1 for β ⩽ 10−4.

Bounds on long-range hadronic interactions

Abstract The stopping power of slow monopoles ( V / c ⩽10 −3 ) in stellar plasma is calculated by considering both binary collisions and collective effects and using realistic electromagnetic response functions. The cross section for trapping by the sun is evaluated and the following phenomenological consequences are analyzed: monopole component of the solar magnetic field, solar energy production and solar neutrinos flux. Bounds on monopole flux more stringent than Parkers bound are derived.

Magnetic monopoles and dyons interacting with matter

Abstract Bounds on long-range nucleon-nucleon interactions are obtained from the analysis of gravitational experiments, molecular spectroscopy and low and intermediate energy nuclear phenomena. Previously existing results are improved, and rather general types of potentials are considered: potentials behaving as 1/ R n and potentials corresponding to the exchange of scalar and pseudo-scalar particles.

AUGER LIKE FORMATION OF MONOPOLIUM

Abstract After a brief, critical review of the Drell et al. method, we propose an alternative approach suitable for the of dyon and dyon-negative-electron (Dy-e) system interactions with hydrogen and helium. This method, called the impact parameter method (IPM), has been used already in atomic collisions and allows the calculation of energy losses in H and He. We report these quantities and comment on their behaviour versus the relative velocities between Dy or Dy-e and atoms; we compare them to the monopole results. Conclusions in relation to planned experiments are outlined.

On the significance of muon distribution between the fission fragments

Abstract We study the formation of monopolium by Auger-like processes, starting from monopole-proton or monopole-electron bound states: (MX)+ M →(M M )+X . Both relativistic and non-relativistic bound states are envisaged. The ratio of Auger to radiative rate is of order 1013 at temperatures allowing the existence of (MX) bound states. In spite of this, also the Auger mechanism is unable to match theoretical and experimental previsions on the present monopole density in the universe.