اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدThe Karlsruhe Astrophysical Database of Nucleosynthesis in Stars Project - Status and Prospects
159
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The KADoNiS (Karlsruhe Astrophysical Database of Nucleosynthesis in Stars) project is an astrophysical online database for cross sections relevant for nucleosynthesis in the $s$ process and the $gamma$ process. The $s$-process database (www.kadonis.org) was started in 2005 and is presently facing its 4th update (KADoNiS v1.0). The $gamma$-process database (KADoNiS-p, www.kadonis.org/pprocess) was recently revised and re-launched in March 2013. Both databases are compilations for experimental cross sections with relevance to heavy ion nucleosynthesis. For the $s$ process recommended Maxwellian averaged cross sections for $kT$= 5-100~keV are given for more than 360 isotopes between $^{1}$H and $^{210}$Bi. For the $gamma$-process database all available experimental data from $(p,gamma), (p,n), (p,alpha), (alpha,gamma), (alpha,n)$, and $(alpha,p)$ reactions between $^{70}$Ge and $^{209}$Bi in or close to the respective Gamow window were collected and can be compared to theoretical predictions. The aim of both databases is a quick and user-friendly access to the available data in the astrophysically relevant energy regions.
قيم البحث
اقرأ أيضاً
Since April 2005 a regularly updated stellar neutron cross section compilation is available online at http://nuclear-astrophysics.fzk.de/kadonis. This online-database is called the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars project
and is based on the previous Bao et al. compilation from the year 2000. The present version textsc{KADoNiS} v0.2 (January 2007) includes recommended cross sections for 280 isotopes between $^{1}$H and $^{210}$Po and 75 semi-empirical estimates for isotopes without experimental information. Concerning stellar $(n,gamma)$ cross sections of the 32 stable, proton-rich isotopes produced by the $p$ process experimental information is only available for 20 isotopes, but 9 of them have rather large uncertainties of $geq$9%. The first part of a systematic study of stellar $(n,gamma)$ cross sections of the $p$-process isotopes $^{74}$Se, $^{84}$Sr, $^{102}$Pd, $^{120}$Te, $^{130}$Ba, $^{132}$Ba, $^{156}$Dy, and $^{174}$Hf is presented. In another application textsc{KADoNiS} v0.2 was used for an modification of a reaction library of Basel university. With this modified library $p$-process network calculations were carried out and compared to previous results.
The rapid neutron capture process (r process) is believed to be responsible for about half of the production of the elements heavier than iron and contributes to abundances of some lighter nuclides as well. A universal pattern of r-process element ab
undances is observed in some metal-poor stars of the Galactic halo. This suggests that a well-regulated combination of astrophysical conditions and nuclear physics conspires to produce such a universal abundance pattern. The search for the astrophysical site for r-process nucleosynthesis has stimulated interdisciplinary research for more than six decades. There is currently much enthusiasm surrounding evidence for r-process nucleosynthesis in binary neutron star mergers in the multi-wavelength follow-up observations of kilonova/gravitational-wave GRB170807A/GW170817. Nevertheless, there remain questions as to the contribution over the history of the Galaxy to the current solar-system r-process abundances from other sites such as neutrino-driven winds or magnetohydrodynamical ejection of material from core-collapse supernovae. In this review we highlight some current issues surrounding the nuclear physics input, astronomical observations, galactic chemical evolution, and theoretical simulations of r-process astrophysical environments with the goal of outlining a path toward resolving the remaining mysteries of the r process.
The Karlsruhe Astrophysical Database of Nucleosynthesis in Stars (KADoNiS) project is an online database for experimental cross sections relevant to the $s$ process and $p$ process. It is available under http://nuclear-astrophysics.fzk.de/kadonis and
consists of two parts. Part 1 is an updated sequel to the well-known Bao et al. compilations from 1987 and 2000, which is online since April 2005. An extension of this $s$-process database to $(n,p)$ and $(n,alpha)$ cross sections at $kT$= 30 keV, as in the first version of the Bao compilation, is planned. The second part of KADoNiS is a $p$-process library, which includes all available experimental data from $(p,gamma)$, $(p,n)$, $(alpha,gamma)$, $(alpha,n)$, $(alpha,alpha)$, $(n,alpha)$ and $(gamma,n)$ reactions in or close to the respective Gamow window. Despite the great number of reactions required for a $p$-process reaction network, experimental data is still scarce and up to now restricted to stable targets. Given here is a short overview about the present status of the KADoNiS database.
FAZIA is designed for detailed studies of the isospin degree of freedom, extending to the limits the isotopic identification of charged products from nuclear collisions when using silicon detectors and CsI(Tl) scintillators. We show that the FAZIA te
lescopes give isotopic identification up to Z$sim$25 with a $Delta$E-E technique. Digital Pulse Shape Analysis makes possible elemental identification up to Z=55 and isotopic identification for Z=1-10 when using the response of a single silicon detector. The project is now in the phase of building a demonstrator comprising about 200 telescopes.
ANAIS (Annual modulation with NAI Scintillators) experiment aims to look for dark matter annual modulation with 250 kg of ultrapure NaI(Tl) scintillators at the Canfranc Underground Laboratory (LSC), in order to confirm the DAMA/LIBRA positive signal
in a model-independent way. The detector will consist in an array of close-packed single modules, each of them coupled to two high efficiency Hamamatsu photomultipliers. Two 12.5 kg each NaI(Tl) crystals provided by Alpha Spectra are currently taking data at the LSC. These modules have shown an outstanding light collection efficiency (12-16 phe/keV), about the double of that from DAMA/LIBRA phase 1 detectors, which could enable reducing the energy threshold down to 1 keVee. ANAIS crystal radiopurity goals are fulfilled for 232Th and 238U chains, assuming equilibrium, and in the case of 40K, present crystals activity (although not at the required 20 ppb level) could be acceptable. However, a 210Pb contamination out-of-equilibrium has been identified and its origin traced back, so we expect it will be avoided in next prototypes. Finally, current status and prospects of the experiment considering several exposure and background scenarios are presented.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
