Recoil Properties ofSm142from Nuclear Reactions Induced by Heavy Ions. I. Samarium Compound Systems

Abstract

By means of thin-target differential-range experiments, we have measured the average ranges and range straggling of 72-min Sm 142 recoils from a number of nuclear reactions induced by heavy ions. Beams of Li 6 , Li 7 , B 10 , C 12 , and N 14 with kinetic energies up to 10.5 MeV per nucleon were used in conjunction with targets of Cs 133 , Ba 136 , Ba 137 , Ba 138 , La 139 , and Pr 141 . A range-energy curve was obtained for Sm 142 in Al, covering the region 2-10-MeV recoil energy. Strong evidence for a pure compound nucleus reaction mechanism is provided by (a) the uniqueness of the range-energy curve for all the reactions, (b) Gaussian-range distributions, and (c) direct comparison of the experimental ranges with stopping theory. The reaction Nd 142 (a,4w)Sm 142 was studied by integral range methods, and the average ranges in Nd were found to be consistent with theoretical expectations when projected ranges were corrected to true ranges. The experimental straggling parameters are compared with theoretical predictions of straggling inherent in the stopping process. For Li 6 and Li 7 experiments, where the recoil velocities are smaller than the Bohr velocity (2.2X10 8 cm/sec), an attempt is made to extract the range straggling due to the nuclear reaction. From this analysis, qualitative information is obtained about the average total energy removed by neutrons and photons.

Spectral flow, condensate and topology in lattice QCD

“…Our study of the spectral flow of H L (m) has consequences to the study of vector gauge theories with massless quarks using domain wall fermions [7]. In the domain wall formalism with no explicit quark mass term, the fermion mass induced by the finite extent of the extra direction is exponentially suppressed for free fermions [7] and in one-loop perturbation theory [20].…”

“…In the domain wall formalism with no explicit quark mass term, the fermion mass induced by the finite extent of the extra direction is exponentially suppressed for free fermions [7] and in one-loop perturbation theory [20]. Analytical studies pertaining to the domain wall formalism in the limit of an infinite extent in the extra direction can be found in Ref.…”

“…The original domain wall formalism contained an infinite number of fermions [6]. A practical implementation involves a truncation to a finite number of fermions [7], and the region m > m 1 is of interest in this context. Unlike in the continuum, level crossings on the lattice do not occur at one value of m but in a region of m. This spreading, observed numerically in [3,8,9], is due to the presence of the Wilson term in H L (m).…”

Domain wall fermions and applications

“…The method was introduced by D.B. Kaplan [4,6] and was further developed by Neuberger and Narayanan [5] and by Shamir and Furman [7,8]. Domain wall fermions are defined by extending space-time to five dimensions.…”

“…Four-dimensional fermion fields q, q used in Green's functions are constructed from the s = 0 plus chirality and s = L s − 1 minus chirality components of the five dimensional fields [8]. Gauge fields are introduced by treating the s direction as an internal flavor space [5,6]. They are only defined in fourdimensions, and they do not change along s. This construction is used by today's numerical simulations and is referred to as domain wall fermions.…”