Fri·Apr 9, 2021Friday·April 9, 2021

1. 01*

   Improved Nondestructive Isotopic Analysis with Practical Microcalorimeter Gamma Spectrometers

   Mark Croce🇺🇸 · Daniel Becker🇺🇸 · Katrina E. Koehler🇺🇸 · Joel Ullom🇺🇸

   Advances in both instrumentation and data analysis software are now enabling the first ultra-high-resolution microcalorimeter gamma spectrometers designed for implementation in nuclear facilities and analytical laboratories. With approximately ten times better energy resolution than high-purity germanium detectors, these instruments can overcome important uncertainty limits. Microcalorimeter gamma spectroscopy is intended to provide nondestructive isotopic analysis capabilities with sufficient precision and accuracy to reduce the need for sampling, chemical separations, and mass spectrometry to meet safeguards and security goals. Key milestones were the development of the SOFIA instrument (Spectrometer Optimized for Facility Integrated Applications) and the SAPPY software (Spectral Analysis Program in PYthon). SOFIA is a compact instrument that combines advances in large multiplexed transition-edge sensor arrays with optimized cryogenic performance to overcome many practical limitations of previous systems. With a 256-pixel multiplexed detector array capable of 5000 counts per second, measurement time can be comparable to high-purity germanium detectors. SAPPY was developed to determine isotopic ratios in data from SOFIA and other microcalorimeter instruments with an approach similar to the widely-used FRAM software. SAPPY provides a flexible framework with rigorous uncertainty analysis for both microcalorimeter and HPGe data, allowing direct comparison. We present current results from the SOFIA instrument, preliminary isotopic analysis using SAPPY, and describe how the technology is being used to explore uncertainty limits of nondestructive isotopic characterization, inform safeguards models, and extract improved nuclear data including gamma-ray branching ratios.

   ↳ physics.ins-detnucl-ex1 citation
2. 02*

   The signature of charge dependent directed flow observables by electromagnetic fields in heavy ion collisions

   Yifeng Sun🇮🇹 · Vincenzo Greco🇮🇹 · Salvatore Plumari🇮🇹

   We discuss the generation of the directed flow $v_1(p_T,y_z)$ induced by the electromagnetic field as a function of $p_T$ and $y_z$. Despite the complex dynamics of charged particles due to strong interactions generating several anisotropies in the azimuthal angle, it is possible at $p_T>m$ to directly correlate the splitting in $v_1$ of heavy quarks with different charges to some main features of the magnetic field, and in particular its values at formation and freeze-out time. We further found that the slope of the splitting $d\Delta v_1/d{y}_z{|}_{y_z=0}$ of positively and negatively charged particles at high $p_T$ can be formulated as $d\Delta v_1/d{y}_z{|}_{y_z=0}=-\alpha \frac{\partial \ln f}{\partial p_T}+\frac{2\alpha -\beta }{p_T}$, where the constants $\alpha$ and $\beta$ are constrained by the $y$ component of magnetic fields and the sign of $\alpha$ is simply determined by the difference $\Delta [t{B}_y(t)]$ in the center of colliding systems at the formation time of particles and at the time when particles leave the effective range of electromagnetic fields or freeze out. The formula is derived from general considerations and is confirmed by several related numerical simulations; it supplies a useful guide to quantify the effect of different magnetic field configurations and provides an evidence of why the measurement of $\Delta v_1$ of charm, bottom and leptons from $Z^0$ decay and their correlations are a powerful probe of the initial e.m. fields in ultra-relativistic collisions.

   ↳ nucl-thhep-phnucl-exEur.Phys.J.Plus(2021)·9 citations
3. 03*

   The deconvolution problem of deeply virtual Compton scattering

   V. Bertone🇫🇷 · H. Dutrieux🇫🇷 · C. Mezrag🇫🇷 · H. Moutarde🇫🇷 · P. Sznajder🇵🇱

   Generalised parton distributions are instrumental to study both the three-dimensional structure and the energy-momentum tensor of the nucleon, and motivate numerous experimental programmes involving hard exclusive measurements. Based on a next-to-leading order analysis and a careful study of evolution effects, we exhibit non-trivial generalised parton distributions with arbitrarily small imprints on deeply virtual Compton scattering observables. This means that in practice the reconstruction of generalised parton distributions from measurements, known as the deconvolution problem, does not possess a unique solution for this channel. In this Letter we discuss the consequences on the extraction of generalised parton distributions from data and advocate for a multi-channel analysis.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2021)·92 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.