Quark fragmentation to π±\pi^{\pm}, π0\pi^{0}, K±K^{\pm}, pp and pˉ\bar{p} in the nuclear environment

The influence of the nuclear medium on lepto-production of hadrons was studied in the HERMES experiment at DESY in semi-inclusive deep-inelastic scattering of 27.6 GeV positrons off deuterium, nitrogen and krypton targets. The differential multiplicity for krypton relative to that of deuterium has been measured for the first time for various identified hadrons ($\pi^+$, $\pi^-$, $\pi^0$, $K^+$, $K^-$, $p$ and $\bar{p}$) as a function of the virtual photon energy $\nu$, the fraction $z$ of this energy transferred to the hadron, and the hadron transverse momentum squared $p_t^2$. The multiplicity ratio is strongly reduced in the nuclear medium at low $\nu$ and high $z$, with significant differences among the various hadrons. The distribution of the hadron transverse momentum is broadened towards high $p_t^2$ in the nuclear medium, in a manner resembling the Cronin effect previously observed in collisions of heavy ions and protons with nuclei.Comment: 8 pages, 5 figure

Search for the Xb and other hidden-beauty states in the π+π−ϒ(1S) channel at ATLAS

This Letter presents a search for a hidden-beauty counterpart of the X(3872) in the mass ranges of 10.05–10.31 GeV and 10.40–11.00 GeV, in the channel Xb→π+π−ϒ(1S)(→μ+μ−), using 16.2 fb−1 of pp   collision data collected by the ATLAS detector at the LHC. No evidence for new narrow states is found, and upper limits are set on the product of the Xb cross section and branching fraction, relative to those of the ϒ(2S), at the 95% confidence level using the CLS approach. These limits range from 0.8% to 4.0%, depending on mass. For masses above 10.1 GeV, the expected upper limits from this analysis are the most restrictive to date. Searches for production of the ϒ(13DJ), , and states also reveal no significant signals

Simulations and analysis of fluorescence effects in semiconductor x-ray and gamma-ray detectors

Photon-counting semiconductor detectors are a key technology for reducing dose in clinical x-ray imaging procedures, such as CT, and improving performance in gamma-ray imaging procedures such as SPECT. These detectors offer excellent energy resolution and high spatial resolution. To stop high-energy photons, high-Z semiconductors must be used, such as CdTe, TlBr or other emerging candidates. These crystals often suffer from poor hole transport due to hole trapping, which can greatly affect signal, even when data is primarily collected from anodes. There are many interesting challenges in the production of these detectors as well as in developing complete quantitative models of the photon-matter interaction, charge transport, and signal induction. Prior work in our group has focused on optimal ways to estimate photon interaction parameters (x,y,z) and energy (E). This work is based on statistical models and calibration data. In recent work we are exploring a method to account for k x-ray fluorescence and to model signals induced on a double-sided strip detector. Our approach is Monte-Carlo sampling of interaction details, followed by charge transport and signal induction modeling via weighting potentials. First our simulation creates first and second order statistics for three charge induction cases: simple transport, charge sharing, and x-ray fluorescence. Using mean signals and covariance matrices from these cases we build a likelihood that can be used with maximum likelihood methods to estimate the primary interaction location and classify whether the event's energy deposition involved fluorescence. In planned work we will test the model against experimental semiconductor detector data. © 2022 SPIE.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]