953790
The (t,He3) and (He3, t) reactions as probes of Gamow-Teller strength
It is shown via a study on a Mg-26 target that the (t,He-3) reaction at 115 MeV/nucleon reaction is an accurate probe for extracting Gamow-Teller transition strengths. To do so, the data are complemented by results from the Mg-26(He-3, t) reaction at 140 MeV/nucleon that allows for a comparison of T=2 analog states excited via the mirror reactions. Extracted Gamow-Teller strengths from Mg-26(t,He-3) and Mg-26(He-3, t) are compared with those from Mg-26(d,He-2) and Mg-26(p,n) studies, respectively. A good correspondence is found, indicating probe independence of the strength extraction. Furthermore, we test shell-model calculations using the new USD-05B interaction in the sd-model space and show that it reproduces the experimental Gamow-Teller strength distributions well. In anticipation of further (t,He-3) experiments on medium-heavy nuclei aimed at determining weak-interaction rates of relevance for stellar evolution, a second goal of this work is to improve the understanding of the (t,He-3) and (He-3, t) reaction mechanisms at intermediate energies because detailed studies are scarce. The distorted-wave Born approximation is employed, taking into account the composite structures of the He-3 and triton particles. The reaction model provides the means to explain systematic uncertainties at the 10%-20% level in the extraction of Gamow-Teller strengths as being because of interference between Gamow-Teller Delta L=0,Delta S=1 and Delta L=2,Delta S=1 amplitudes that both contribute to transitions from 0(+) to 1(+) states.
19324012
Fragmentation and splitting of Gamow-Teller resonances in Sn(3He,t)Sb charge-exchange reactions, A=112-124.
Fragmentation and splitting of the Gamow-Teller (GT) strength has been observed in a systematic study of the ([sup 3]He,[ital t]) charge-exchange reaction at [ital E]([sup 3]He)=200 MeV over the entire range of stable Sn isotopes. Triton energy spectra were observed with a high-resolution magnetic spectrometer at angles near [theta]=0[degree] where [Delta][ital L]=0 transitions are enhanced. Excitation energies, widths, 0[degree] cross sections, and strengths [ital B](GT) were determined. A theoretically predicted configuration splitting of the main GT component into two components, expected to be dominant near [ital A]=118 at the onset of the filling of the 1[ital h][sub 11/2] neutron orbital, could not be observed. This may be due to the fact that the total widths of the resonances of 5--6 MeV exceed the predicted splitting. A comparison of the 0[degree] cross sections for the transitions to the GT resonances and the isobaric analog states leads to strengths [ital B](GT) for the main Gamow-Teller components of typically 65% of the sum-rule value of 3([ital N][minus][ital Z]). Three to four additional Gamow-Teller fragments were observed in all final nuclei at lower excitation energies. The excellent energy resolution of the experiment made it possible to observe a pronounced fine structure in these low-lyingmore » resonances which is believed to be due to coupling to two-particle--two-hole doorway states. Also seen with all target nuclei was a systematic sequence of strong [ital J][sup [pi]]=1[sup +] states near the ground states in all Sb isotopes ([ital E][sub [ital x]]=0 to 220 keV). In addition, strong [Delta][ital L]=1 resonances were observed in all nuclei at excitation energies of typically 20 MeV. Furthermore, nonresonant background from quasifree charge exchange was observed. An average of [similar to]85% of all excess neutrons seems to contribute to this background in approximate agreement with results from ([ital e],[ital e][prime][ital p]) experiments.« less
2502593
Dependence of the cross section for inclusive pion double charge exchange on nuclear mass and charge.
Total reaction cross sections for inclusive pion double charge exchange have been obtained at incident pion energies of 180 and 240 MeV for /sup 4/He, /sup 6.7/Li, /sup 9/Be, /sup 12/C, /sup 16/O, /sup 40/Ca, /sup 103/Rh, and /sup 208/Pb. An explanation of the dependence of these cross sections upon the mass and charge of the target nucleus and the charge of the incident pion is suggested in terms of a phenomenological model in which successive single-charge-exchange processes compete with more probable processes such as quasifree scattering.
121478239
Breakup of B-8 at sub-Coulomb energies
43243436
Production of an isomeric, excited radioactive nuclear beam.
125696689
High-resolution study of Gamow-Teller transitions via the Fe-54(He-3, t)Co-54 reaction
119648296
FastSim: A Fast Simulation for the SuperB Detector
We have developed a parameterized (fast) simulation for detector optimization and physics reach studies of the proposed SuperB Flavor Factory in Italy. Detector components are modeled as thin sections of planes, cylinders, disks or cones. Particle-material interactions are modeled using simplified cross-sections and formulas. Active detectors are modeled using parameterized response functions. Geometry and response parameters are configured using xml files with a custom-designed schema. Reconstruction algorithms adapted from BaBar are used to build tracks and clusters. Multiple sources of background signals can be merged with primary signals. Pattern recognition errors are modeled statistically by randomly misassigning nearby tracking hits. Standard BaBar analysis tuples are used as an event output. Hadronic B meson pair events can be simulated at roughly 10Hz.
18134055
Localized shocks
A bstractWe study products of precursors of spatially local operators, Wxntn⋅⋅⋅Wx1t1$$ {W_x}_{{}_n}(tn)\cdot \cdot \cdot {W}_{x_1}\left({t}_1\right) $$, where Wx(t) = e− iHtWxeiHt. Using chaotic spin-chain numerics and gauge/gravity duality, we show that a single precursor fills a spatial region that grows linearly in t. In a lattice system, products of such operators can be represented using tensor networks. In gauge/gravity duality, they are related to Einstein-Rosen bridges supported by localized shock waves. We find a geometrical correspondence between these two descriptions, generalizing earlier work in the spatially homogeneous case.
118055903
New Measurements of Rare K0L and pi0 Decays from Fermilab E799