Mon·May 1, 2017Monday·May 1, 2017

1. 01*

   Measurement of the ${}^{64}$Zn,${}^{47}$Ti(n,p) Cross Sections using a DD Neutron Generator for Medical Isotope Studies

   Andrew Voyles · M.S. Basunia · Jon Batchelder🇺🇸 · Joseph Bauer · Tim Becker · Lee Bernstein🇺🇸 · Eric Matthews · Paul Renne · Daniel Rutte · Mauricio Unzueta · Karl van Bibber🇺🇸

   Cross sections for the ${}^{47}$Ti(n,p)${}^{47}$Sc and ${}^{64}$Zn(n,p)${}^{64}$Cu reactions have been measured for quasi-monoenergetic DD neutrons produced by the UC Berkeley High Flux Neutron Generator (HFNG). The HFNG is a compact neutron generator designed as a "flux-trap" that maximizes the probability that a neutron will interact with a sample loaded into a specific, central location. The study was motivated by interest in the production of ${}^{47}$Sc and ${}^{64}$Cu as emerging medical isotopes. The cross sections were measured in ratio to the ${}^{113}$In(n,n')${}^{113m}$In and ${}^{115}$In(n,n')${}^{115m}$In inelastic scattering reactions on co-irradiated indium samples. Post-irradiation counting using an HPGe and LEPS detectors allowed for cross section determination to within 5% uncertainty. The ${}^{64}$Zn(n,p)${}^{64}$Cu cross section for 2.76${}_{-0.02}^{+0.01}$ MeV neutrons is reported as 49.3 $\pm$ 2.6 mb (relative to ${}^{113}$In) or 46.4 $\pm$ 1.7 mb (relative to ${}^{115}$In), and the ${}^{47}$Ti(n,p)${}^{47}$Sc cross section is reported as 26.26 $\pm$ 0.82 mb. The measured cross sections are found to be in good agreement with existing measured values but with lower uncertainty (< 5%), and also in agreement with theoretical values. This work highlights the utility of compact, flux-trap DD-based neutron sources for nuclear data measurements and potentially the production of radionuclides for medical applications.

   nucl-exNucl.Instrum.Meth.B(2017)·8 citations
2. 02*

   Experimental probe on the production of ${}^{97}$Ru from ${}^7$Li+${}^{93}$Nb reaction: A study on the precompound emissions

   Deepak Kumar · Moumita Maiti · Susanta Lahiri🇮🇳

   Background: Interaction of weakly bound heavy-ions with an intermediate or heavy target is not yet understood completely due to the scarcity of experimental data. In order to develop a clear understanding of breakup fusion or preequilibrium emission even at low energy range, 3--10 MeV/nucleon, more experimental investigations are necessary. Purpose: Study of reaction mechanisms involved in the weakly bound heavy-ion induced reaction, ${}^7$Li + ${}^{93}$Nb, at low energies by measuring the production cross sections of the residual radionuclides. Method: Natural niobium (${}^{93}$Nb) foil, backed by aluminium (Al) catcher, arranged in a stack was bombarded by ${}^7$Li ions of 20-45 MeV energy. Activity of the residues produced in each ${}^{93}$Nb target was measured by off-line $\gamma$-ray spectrometry after the end of bombardment (EOB) and cross sections were calculated. Experimental cross sections were compared with those computed using compound and precompound models. Results: In general, measured excitation functions of all residues produced in ${}^7$Li + ${}^{93}$Nb reaction showed good agreement with the model calculations based on Hauser-Feshbach formalism and exciton model for compound and precompound processes, respectively. Significant preequilibrium emission of neutrons was observed at the relatively high energy tail of the excitation function of ${}^{97}$Ru. Conclusions: Preequilibrium process played an important role for the enhancement of cross-section in $xn$ reaction channel over the compound reaction mechanism at higher energies for ${}^7$Li + ${}^{93}$Nb reaction. Additionally, indirect evidence of incomplete or breakup fusion was also perceived.

   nucl-exPRC(2016)·30 citations
3. 03*

   High Spatial-Resolution Fast Neutron Detectors for Imaging and Spectrometry

   Ilan Mor🇮🇱

   Two detection systems based on optical readout were developed: a. Integrative optical detector A 2nd generation of Time-Resolved Integrative Optical Neutron (TRION) detector was developed. It is based on an integrative optical technique, which permits fast-neutron energy-resolved imaging via time-gated optical readout. This mode of operation allows loss-free operation at very high neutron-flux intensities. The TRION neutron imaging system can be regarded as a stroboscopic photography of neutrons arriving at the detector on a few-ns time scale. As this spectroscopic capability is based on the Time-of-Flight (TOF) technique, it has to be operated in conjunction with a pulsed neutron source, such as an ion accelerator producing 1-2 ns wide beam pulses at MHz repetition rates. TRION is capable of capturing 4 simultaneous TOF frames within a single accelerator pulse and accumulating them over all pulses contained within a finite acquisition time. The detector principle of operation, simulations and experimental results are described. b. Fibrous optical detector A fast neutron imaging detector based on micrometric glass capillaries loaded with high- refractive-index liquid scintillator has been developed. Neutron energy spectrometry is based on event-by-event detection and reconstruction of neutron energy from the measurement of the recoil proton track projection length and the amount of light produced in the track. In addition, the detector can provide fast-neutron imaging with position resolution of tens of microns. The detector principle of operation, simulations and experimental results obtained with a small detector prototype are described. Track-imaging of individual recoil protons from incident neutrons in the range of 2-14 MeV are demonstrated as well as preliminary results of detector spectroscopic capabilities. Keywords: Fast neutron resonance radiography; Time-of-Flight; Fast neutron imaging; Energy-resolved imaging; Neutron spectrometry; Capillary array; Liquid scintillator

   ↳ physics.ins-detnucl-ex0 citations
4. 04*

   Inclusive Breakup Theory of Three-Body Halos

   M. S. Hussein🇧🇷 · L. A. Souza · E. Chimanski · B. V. Carlson🇧🇷 · T. Frederico🇧🇷

   We present a recently developed theory for the inclusive breakup of three-fragment projectiles within a four-body spectator model \cite{CarPLB2017}, for the treatment of the elastic and inclusive non-elastic break up reactions involving weakly bound three-cluster nuclei in $A(a,b)X$ / $a=x_1+x_2+b$ collisions. The four-body theory is an extension of the three-body approaches developed in the 80's by Ichimura, Autern and Vincent (IAV) \cite{IAV1985}, Udagawa and Tamura (UT) \cite{UT1981} and Hussein and McVoy (HM) \cite{HM1985}. We expect that experimentalists shall be encouraged to search for more information about the $x_1+x_2$ system in the elastic breakup cross section and that also further developments and extensions of the surrogate method will be pursued, based on the inclusive non-elastic breakup part of the $b$ spectrum.

   ↳ nucl-thnucl-exEPJ Web Conf.(2017)·3 citations
5. 05*

   Relativistic fluid dynamics with spin

   Wojciech Florkowski🇵🇱 · Bengt Friman🇩🇪 · Amaresh Jaiswal🇩🇪 · Enrico Speranza🇩🇪

   Using the conservation laws for charge, energy, momentum, and angular momentum, we derive hydrodynamic equations for the charge density, local temperature, and fluid velocity, as well as for the spin tensor, starting from local equilibrium distribution functions for particles and antiparticles with spin 1/2. The resulting set of differential equations extend the standard picture of perfect-fluid hydrodynamics with a conserved entropy current in a minimal way. This framework can be used in space-time analyzes of the evolution of spin and polarization in various physical systems including high-energy nuclear collisions. We demonstrate that a stationary vortex, which exhibits vorticity-spin alignment, corresponds to a special solution of the spin-hydrodynamical equations.

   ↳ nucl-thhep-phnucl-exPRC(2018)·321 citations

* 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.