Nuclear Experiment·nucl-ex
13 papers—9 primary·4 cross-listed·reconstructed*
J.L. Gross🇺🇸 · M. Thoennessen🇺🇸
Currently, twenty-eight gallium, thirty-one germanium, thirty-five lutetium, and thirty-six hafnium isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.
Designing and optimizing ion optical systems is often a complex and difficult task, which requires the use of computational tools to iterate and converge towards the desired characteristics and performances of the system. Very often these tools are not well adapted for exploring the numerous degrees of freedom, rendering the process long and tedious, as well as somewhat random due to the very large number of local minima typically found when looking for a particular optical solution. This paper presents a novel approach to finding the desired solution of an optical system, by providing the user with an instant feedback of the effects of changing parameters. The process of finding an approximate solution by manually adjusting parameters is greatly facilitated, at which point the final tune can be calculated by minimization according to a number of constraints.
Production cross sections of evaporation residues, Tb, Tb, Tb and Gd, have been measured using the stacked foil technique followed by off-line -spectrometry in C induced reactions on naturally abundant mononuclidic praseodymium target in the 44-79 MeV incident energy range. Measured data have been interpreted comparing with previous measurements and theoretical prediction of nuclear reaction model code \textsc{PACE4}. About 5% and 14% of the theoretical cross sections have been measured for Tb and Tb, respectively. The new cross sections of Tb complement those measured earlier by -spectrometry. Cross sections of Tb are comparable to the theory. Cumulative cross section of Gd sheds light on the nuclear reaction mechanism. In addition, a discussion has been made to show the feasibility of producing Tb in - and -induced reactions on gadolinium isotopes.
Moumita Maiti🇮🇳 · Susanta Lahiri🇮🇳
Earlier we reported theoretical studies on the probable production of astatine radionuclides from Li and Be-induced reactions on natural lead and thalliun targets, respectively. For the first time, in this report, production of astatine radionuclides has been investigated experimentally with two heavy ion induced reactions: Be+Tl and Li+Pb. Formation cross sections of the evaporation residues, At, produced in (HI, xn) channel, have been measured by the stacked-foil technique followed by the off-line -spectrometry at the low incident energies (50 MeV). Measured excitation functions have been explained in terms of compound nuclear reaction mechanism using Weisskopf-Ewing and Hauser-Feshbach model. Absolute cross section values are lower than the respective theoretical predictions.
M. I. Adamovich🇷🇺 · I. A. Konorov🇷🇺 · V. G. Larionova🇷🇺 · N. G. Peresadko🇷🇺 · S. P. Kharlamov🇷🇺 · V. G. Bogdanov🇷🇺 · V. A. Plyushchev🇷🇺 · Z. I. Solovyeva🇷🇺
Inelastic interactions of nuclei accelerated to a momentum of 4.5 GeV/ per projectile nucleon with photoemulsion nuclei have been investigated. The main features of these interactions - mean ranges of Li nuclei, mean multiplicities of secondaries, the isotopic composition of fragments, fragmentation channels, and the mean transverse momenta of projectile fragments - have been measured. The probability of the charge-exchange reaction featuring lithium nuclei has been determined. The results obtained for the Li nucleus have been compared with data for other nuclei. The observed features of Li interactions with other nuclei indicate that the Li structure in the form of the loosely bound system consisting of an -particle and a deuteron cluster clearly manifests itself in these interactions. Events resulting in the coherent dissociation of Li nuclei into He+, He+, and and involving low-lying excitations of Li have been observed.
New generation experiments on search for neutrinoless double beta decay with sensitivity to effective Majorana neutrino mass on the level 3-5 meV is discussed. Possible restrictions at achievement of this purpose (possibility to produce big amount of enriched isotopes, possibility to reach very low background level, energy resolution and possible cost of experiments) are considered. It is shown that for realization of so ambitious project 10 tons (or more) of enriched isotope is required. Background index should be on the level 10 c/kg keV y. Besides, the energy resolution of the detector should be not worse than 1-2%. It is shown that TeO low temperature bolometer looks as the most realistic candidate for such experiments. Under some conditions experiments with Ge, Mo and Xe can be realized too.
S. Masciocchi (for the ALICE Collaboration)🇩🇪
Electron spectra measured with ALICE at mid-rapidity are used to study the production of hadrons carrying a charm or a beauty quark. The production cross section of electrons from heavy-flavour hadron decays is measured in pp collisions at =7 TeV. Electrons from the beauty decays are identified via the displacement from the interaction vertex. From the electron spectra measured in Pb--Pb collisions, we determine the nuclear modification factor, which is sensitive to the heavy-quark energy loss in a hot strongly interacting medium.
A total of 194 isotopes with 11 Z 19 have been identified to date. The discovery of these isotopes which includes the observation of unbound nuclei, is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.
FINUDA Collaboration: M.Agnello · L.Benussi · M.Bertani · H.C.Bhang · G.Bonomi · E.Botta · M.Bregant · T.Bressani · S.Bufalino · L.Busso · D.Calvo · P.Camerini and 27 other authors
This letter is concerned with the study of the reaction in p-shell nuclei, i.e., , , and . The emission rates are reported as a function of . These rates are discussed in comparison with previous findings. The ratio in p-shell nuclei is found to depart largely from that on hydrogen, which provides support for large in-medium effects possibly generated by the sub-threshold . The continuum momentum spectra of prompt pions and free sigmas are also discussed as well as the missing mass behavior and the link with the reaction mechanism. The apparatus used for the investigation is the FINUDA spectrometer operating at the DANE -factory (LNF-INFN, Italy).
Rudolph C. Hwa🇺🇸 · Lilin Zhu🇨🇳
The transverse momentum distributions of identified hadrons produced in Pb-Pb collisions at the Large Hadron Collider (LHC) are studied in the low and intermediate range for GeV/c. All four spectra () can be well reproduced in the recombination model based on a common thermal parton distribution of light and strange quarks and on shower partons emitted in hard and semihard jets. Two essential parameters are adjusted to fit the data, one being the inverse slope of the thermal distribution and the other revealing the degree of momentum degradation in the medium. Various combinations of thermal and shower parton components are calculated, showing the dominance of minijets. The effect of minijets is to produce harder baryons than mesons resulting in their ratio to peak at around GeV/c. Substantial portion of the jet energy is found to be lost to the dense medium before the partons emerge at the surface to undergo hadronization by recombination.
In tackling QCD, a constructive feedback between theory and extant and forthcoming experiments is necessary in order to place constraints on the infrared behaviour of QCD's \beta-function, a key nonperturbative quantity in hadron physics. The Dyson-Schwinger equations provide a tool with which to work toward this goal. They connect confinement with dynamical chiral symmetry breaking, both with the observable properties of hadrons, and hence provide a means of elucidating the material content of real-world QCD. This contribution illustrates these points via comments on: in-hadron condensates; dressed-quark anomalous chromo- and electro-magnetic moments; the spectra of mesons and baryons, and the critical role played by hadron-hadron interactions in producing these spectra.
Tomás R. Rodríguez🇩🇪 · J. Luis Egido🇪🇸
We study the low-lying energy spectrum of the rp-process waiting point nucleus 80Zr with state-of-the-art beyond mean field methods with the Gogny D1S interaction. Symmetry restoration and configuration mixing of axial and triaxial shapes are included in the calculations. Five 0+ states corresponding to different nuclear shapes are obtained below 2.25 MeV and several rotational and {\gamma}- bands built upon them are identified. Nevertheless, these states do not modify the {\beta}-decay half-life having a negligible effect in the rp-process. A good agreement with the available experimental data is obtained.
Tomás R. Rodríguez🇩🇪 · J. Luis Egido🇪🇸
We study the structure of the neutron rich S isotope with modern configuration mixing methods based on the Gogny interaction including beyond-mean-field effects. Restoration of particle number and rotational symmetries are taken into account as well as shape mixing in the whole triaxial plane. We obtain a qualitative agreement between the calculated spectrum and the experimental data reported recently. Very extended collective wave functions in the plane are found for the lowest states, corresponding to very flat potentials, indicating strong configuration mixing and supporting the weakening of the N=28 magic number.
* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.