Search results for "Elementary Particle"
showing 10 items of 659 documents
Absorptive effects inK+Λphotoproduction on nucleons and nuclei
1989
Incorporating final state correlation effects, we have reinvestigated the ..gamma.. /sup 1/H..-->..K/sup +/..lambda.. elementary process. Our model not only resolves the persisting trouble of the small KN..lambda.. coupling constant, but also yields agreement with cross section data at higher energies. Using our amplitudes, we calculate angular distributions for the reaction /sup 16/O(..gamma..,K/sup +/)/sub ..lambda..//sup 16/N . While the forward cross section increases with increasing energy, the total cross section is almost constant from E/sub ..gamma../ = 1.2 GeV through 2 GeV, suggesting that rather low photon energies hold promise for exploration of hypernuclear excitations.
Electromagnetic production of polarization in hypernuclei.
1991
The formation of polarized hypernuclei through kaon photoproduction is investigated in a distorted-wave impulse approximation approach. The polarization depends strongly on the model used to describe the elementary process. For one particular model and certain well populated states the amount of polarization may reach up to 50%. We present cross sections and polarizations for kaon photoproducton on $^{16}\mathrm{O}$, $^{28}\mathrm{Si}$, $^{56}\mathrm{Fe}$, and $^{89}\mathrm{Y}$ and demonstrate the sensitivity of polarization to distortion and nonlocal effects. More information on the elementary process is needed before the feasibility of such measurements can be established.
Gamow-Teller Transitions Studied in ([sup 3]He, t) Reaction and Analogous β decay
2010
Due to the simplicity of the στ operator that causes Gamow‐Teller (GT) transitions, they are the most popular nuclear weak process in the Universe. The GT transitions in pf‐shell nuclei, for example, starting from stable Tz = +1 and proton‐rich Tz = +1 nuclei, where Tz = (N−Z)/2, play important roles in the supernova‐explosion or rp‐process nucleosynthesis. In the β‐decay study of pf‐shell nuclei, half‐lives can be measured rather accurately. On the other hand, in a high‐resolution (3He, t) charge‐exchange reaction at 0°, individual GT transitions up to high excitations can be studied. In order to derive reliable GT transition strengths B(GT), we present a unique analysis that combines the …
Meson and isobar degrees of freedom in light nuclei
1983
The role of mesonic and isobar degrees of freedom in various electromagnetic processes is reviewed for light nuclei. Special emphasis is laid on the deuteron, which allows the cleanest answers within the non-relativistic framework. The origin of the photonuclear enhancement with respect to both exchange forces and exchange currents is discussed in detail.
Subnuclear Degrees of Freedom in Photoabsorption and Scattering
1986
One of the main fields of interest in medium energy nuclear physics is the study of subnuclear or non-nucleonic degrees of freedom (d.o.f.) in nuclei, like meson and isobar or quark-gluon degrees of freedom. It bridges the gap between classical or low energy nuclear physics as understood in terms of nucleon-only degrees of freedom and elementary particle or high energy physics. Hereby one may distinguish roughly two major objectives.
Mass Spectrometry Using Paul Traps
2009
Mass is one of the basic quantities to characterize any material object, whether an atom, molecule, nucleus, or elementary particle. The measurement of mass therefore serves to detect and identify atomic, molecular, and nuclear species, and can help determine their structure and binding energy. For example, a precise determination of the mass of a nucleus is of importance through its binding energy, not only for various aspects of nuclear physics but also for other branches of physics, e.g. tests of the weak interaction, of quantum electrodynamics, and of the standard model [46]. Also in astrophysics the masses of unstable isotopes involved in stellar nucleosynthesis, especially the r proce…
Radiative muon capture on 12C and 16O
1979
Abstract We study exclusive radiative muon capture on 12 C(g.s.) leading to 12 B(g.s.), and on 16 O(g.s.) leading to 16 N(0 − , 120 keV). Our investigation, which is based on impulse approximation, puts special emphasis on elementary particle aspects of radiative capture, such as tests of magnitude and momentum transfer dependence of the induced pseudoscalar, and possible contributions of axial currents of second kind (weak electricity). We calculate several correlation observables which are sensitive to the nucleonic currents but depend very little on the structure of the nuclear initial and final states. In particular, it is shown that in capture on 12 C the polarization and alignment of …
The relativistic spin-orbit current in deuteron photodisintegration below and above ?-threshold
1988
It is shown that the spin-orbit current which leads to an improved description ofd(γ,p)n below π-threshold is essentially a two-body exchange effect. This is demonstrated by separation of its one-body contribution. Furthermore, above π-threshold its inclusion leads to an improved agreement with experiment, in particular for the differential cross section in the Δ-excitation region.
Proton emission off nuclei induced by kaons in flight
2010
We study the (K-, p) reaction on nuclei with a 1 GeV/c momentum kaon beam, paying special attention to the region of emitted protons having kinetic energy above 600 MeV, which was used to claim a deeply attractive kaon nucleus optical potential. Our model describes the nuclear reaction in the framework of a local density approach and the calculations are performed following two different procedures: one is based on a many-body method using the Lindhard function and the other is based on a Monte Carlo simulation. The simulation method offers flexibility to account for processes other than kaon quasielastic scattering, such as K- absorption by one and two nucleons, producing hyperons, and all…
Structure ofIn112nucleus
1988
The \ensuremath{\gamma}-ray spectra of the $^{112}\mathrm{Cd}$(p,n\ensuremath{\gamma}${)}^{112}$In and $^{109}\mathrm{Ag}$(\ensuremath{\alpha},n\ensuremath{\gamma}${)}^{112}$In reactions were measured with Ge(Li) spectrometers for bombarding energies of 4.8 MeV protons and 17.1 MeV \ensuremath{\alpha} particles. The energies and relative intensities of 79 $^{112}\mathrm{In}$ \ensuremath{\gamma}-ray transitions have been determined. The electron spectra were measured with combined magnet plus Si(Li) as well as superconducting magnetic lens plus Si(Li) spectrometers. Internal conversion coefficients of 40 $^{112}\mathrm{In}$ transitions have been determined, and the level scheme of $^{112}\ma…