119265499
Production cross sections of neutron rich isotopes from a 82Se beam
Production cross sections for neutron-rich nuclei from the fragmentation of a 82Se beam at 139 MeV/u were measured. The longitudinal momentum distributions of 122 neutron-rich isotopes of elements 11 ≤ Z ≤ 32 were determined by varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including several isotopes first observed in this work. These are the most neutron-rich nuclides of the elements 22 ≤ Z ≤ 25 (64Ti, 67V, 69Cr, 72Mn). One event was registered consistent with 70Cr, and another one with 75Fe. A one-body Qg systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. The current results confirm those of our previous experiment with a 76Ge beam: enhanced production cross sections for neutron-rich fragments near Z = 20.
118251608
Projectile fragmentation of Ca40, Ca48, Ni58, and Ni64 at 140 MeV/nucleon
We have measured fragment cross-sections of projectile fragmentation reactions using primary beams of $^{40}\mathrm{Ca}$, $^{48}\mathrm{Ca}$, $^{58}\mathrm{Ni}$, and $^{64}\mathrm{Ni}$ at 140 MeV/nucleon on $^{9}\mathrm{Be}$ and $^{181}\mathrm{Ta}$ targets. The cross-sections were obtained by integrating the momentum distributions of isotopes with $Z\ensuremath{\geqslant}5$ measured in the A1900 fragment separator. We compare the extracted cross-sections to the predictions of the empirical parametrization of fragmentation cross-sections (EPAX).
117037614
Identification of 45 New Neutron-Rich Isotopes Produced by In-Flight Fission of a 238U Beam at 345 MeV/nucleon
A search for new isotopes using in-flight fission of a 345 MeV/nucleon 238 U beam has been carried out at the RI Beam Factory at the RIKEN Nishina Center. Fission fragments were analyzed and identi...
54223660
The program LISE: a simulation of fragment separators
This paper describes the program LISE which simulates the operation of fragment separators used to produce radioactive beams via fragmentation. Various aspects of the physical phenomena involved in the production of such radioactive beams are discussed. They include fragmentation cross-sections, energy losses in materials, ionic charge-state distributions, as well as ion optics calculations and acceptance effects. This program is highly user-friendly, and is designed not only to forecast intensities and purities for planning future experiments, but also for beam tuning during experiments where its results can be quickly compared to on-line data. In addition, several general-purpose tools such as a physical parameters calculator, a database of nuclear properties, and relativistic two-body kinematics calculations make it useful even for experiments with stable beams. After a general description of fragment separators, the principles underlying the calculations are presented, followed by a practical description of the program and its features. Finally, a few examples of calculations are compared to on-line data, both qualitatively and quantitatively.
118688563
Isotopic fission fragment distributions as a deep probe to fusion-fission dynamics
During the fission process, the atomic nucleus deforms and elongates up to the two fragments inception and their final separation at the scission deformation. The evolution of the nucleus energy with deformation defines a potential energy landscape in the multidimensional deformation space. It is determined by the macroscopic properties of the nucleus, and is also strongly influenced by the single-particle structure of the nucleus, which modifies the macroscopic energy minima. The fission fragment distribution is a direct consequence of the deformation path the nucleus has encountered, and therefore is the most genuine experimental observation of the potential energy landscape of the deforming nucleus. Very asymmetric fusion-fission reactions at energy close to the Coulomb barrier, produce well-defined conditions of the compound nucleus formation, where processes such as quasi-fission, pre-equilibrium emission and incomplete fusion are negligible. In the same time, the excitation energy is sufficient to reduce significantly structural effects, and mostly the macroscopic part of the potential is responsible for the formation of the fission fragments. We use inverse kinematics combined with a spectrometer to select and identify the fission fragments produced in 238U+12C at a bombarding energy close to and well-above the Coulomb barrier. For the first time, the isotopic yields are measured over the complete atomic-number distribution, between Z=30 and Z=63. In the experimental set-up, it is also possible to identify transfer-induced reactions, which lead to low-energy fission
120651816
The code LISE: A new version for "Windows"
Abstract The LISE code is intended to simulate medium-energy and high-energy fragment separators with electrostatic and/or magnetic selections. It is based on first-order optics and transport integral convolution techniques. Fragment separators such as LISE3, SISSI/LISE3 and SPEG at GANIL, FRS at GSI, COMBAS and ACCULINA at Dubna, A1200 and A1900 at NSCL, and RIPS at RIKEN are based on the separation of projectile-like fragments, and can be easily simulated via optical configuration files. The reaction mechanism assumed in this program is projectile fragmentation, suitable to simulate experiments at beam energies above 30  A  MeV. However, built-in tools such as the physical calculator, nucleus database utilities, relativistic reaction kinematics calculations and beam optics transport calculations make it a very useful tool below this energy limit as well. The program can therefore be used for forecasting and tuning experiments using heavy-ion beams with energies ranging from 10 keV up to a few GeV per nucleon.
118467843
Analytic result for the one-loop scalar pentagon integral with massless propagators
The method of dimensional recurrences proposed by Tarasov (1996, 2000) [1] ;  [2] is applied to the evaluation of the pentagon-type scalar integral with on-shell external legs and massless internal lines. For the first time, an analytic result valid for arbitrary space–time dimension d and five arbitrary kinematic variables is presented. An explicit expression in terms of the Appell hypergeometric function F3F3 and the Gauss hypergeometric function F12, both admitting one-fold integral representations, is given. In the case when one kinematic variable vanishes, the integral reduces to a combination of Gauss hypergeometric functions F12. For the case when one scalar invariant is large compared to the others, the asymptotic values of the integral in terms of Gauss hypergeometric functions F12 are presented in d=2−2ed=2−2e, 4−2e4−2e, and 6−2e6−2e dimensions. For multi-Regge kinematics, the asymptotic value of the integral in d=4−2ed=4−2e dimensions is given in terms of the Appell function F3F3 and the Gauss hypergeometric function F12.
118380334
Color-kinematic duality for form factors
A bstractRecently a powerful duality between color and kinematics has been proposed for integrands of scattering amplitudes in quite general gauge theories. In this paper the duality proposal is extended to the more general class of gauge theory observables formed by form factors. After a discussion of the general setup the existence of the duality is verified in two- and three-loop examples in four-dimensional maximally supersymmetric Yang-Mills theory which involve the stress energy tensor multiplet. In these cases the duality reproduces known results in a particularly transparent and uniform way. As a non- trivial application we obtain a very simple form of the integrand of the four-loop two-point (Sudakov) form factor which passes a large set of unitarity cut checks.