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Results for “GAMMA DECAY”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

NAIS: Nuclear activation-based imaging spectroscopy

In recent years, the development of high power laser systems led to focussed intensities of more than 10{sup 22} W/cm{sup 2} at high pulse energies. Furthermore, both, the advanced high power lasers and the development of sophisticated laser particle acceleration mechanisms facilitate the generation of high energetic particle beams at high fluxes. The challenge of imaging detector systems is to acquire the properties of the high flux beam spatially and spectrally resolved. The limitations of most detector systems are saturation effects. These conventional detectors are based on scintillators, semiconductors, or radiation sensitive films. We present a nuclear activation-based imaging spectroscopy method, which is called NAIS, for the characterization of laser accelerated proton beams. The offline detector system is a combination of stacked metal foils and imaging plates (IP). After the irradiation of the stacked foils they become activated by nuclear reactions, emitting gamma decay radiation. In the next step, an autoradiography of the activated foils using IPs and an analysis routine lead to a spectrally and spatially resolved beam profile. In addition, we present an absolute calibration method for IPs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1972

Californium-252 neutron capture and decay methods for elemental analysis

The feasibility of using a Cf-252 neutron source in conjunction with a capture and/or decay gamma ray method for elemental analysis on lunar or planetary missions was tested. The general problems of using a Cf-252 neutron source for both decay and capture gamma ray analysis in terrestrial environments included the determination of the capture gamma ray spectra by neutron absorption in various metals used for the space hardware, Cf-252 source encapsulation materials, shielding, geometry, and optimum source size for a space mission. Computer data reduction and data transmission techniques were also investigated.

Source record↗
DOE OSTI2015

Enhancing the detector for advanced neutron capture experiments

The Detector for Advanced Neutron Capture Experiments (DANCE) has been used for extensive studies of neutron capture, gamma decay, photon strength functions, and prompt and delayed fission-gamma emission. Despite these successes, the potential measurements have been limited by the data acquisition hardware. We report on a major upgrade of the DANCE data acquisition that simultaneously enables strait-forward coupling to auxiliary detectors, including high-resolution high-purity germanium detectors and neutron tagging array. The upgrade will enhance the time domain accessible for time-of-flight neutron measurements as well as improve the resolution in the DANCE barium fluoride crystals for photons.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

Search for Bottomonium States in Exclusive Radiative Υ ( 2 S ) Decays

We search for bottomonium states in $\Upsilon(2S)$ → ($\bar{bb}$) gamma decays with an integrated luminosity of 24.7fb -1 recorded at the $\Upsilon(2S)$ resonance with the Belle detector at KEK, containing (157.8 ± 3.6) X 10 6 $\Upsilon(2S)$ events. The ($\bar{bb}$) system is reconstructed in 26 exclusive hadronic final states composed of charged pions, kaons, protons, and $K^0_S$ mesons. We find no evidence for the state recently observed around 9975 MeV ($X_{\bar{bb}}$) in an analysis based on a data sample of 9.3 X 10 6 $\Upsilon(2S)$ events collected with the CLEO III detector. We set a 90 % confidence-level upper limit on the branching fraction $Β$[$\Upsilon(2S)$ → $X_{\bar{bb}\gamma}$] X $\sum_i$ $B$[$X_{\bar{bb}}$ → $h_i$] $<$ 4.9 X 10 -6 , summed over the exclusive hadronic final states employed in our analysis. This result is an order of magnitude smaller than the measurement reported with CLEO data. We also set an upper limit for the $\eta_b(1S)$ state of $B$[$\Upsilon(2S)$ → $\eta_b(1S)\gamma$] X $\sum_i$B[$\eta_b(1S)$ → $h_i$] $<$ 3.7 X 10 -6 .

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Neutronics Evaluation of the Preliminary Design of the Service Cell Door for the Second Target Station

The service cell door needs to provide sufficient shielding to achieve 0.25 mrem/h dose rates in the adjacent room while remote handling operations of waste materials are going on within the service cell for the Second Target Station (STS). This analysis provides a neutronics evaluation of the preliminary design of the service cell door to evaluate the required thickness and the effect of streaming gaps around the door. As radiation source, we use the decay gamma source of the moderator reflector assembly (MRA) of the STS with a decay time of either two days or six months. As the MRA contains a significant amount of beryllium, photonuclear reactions induce a neutron source, which dictates the required door thickness in certain situations. Four scenarios with different MRA positions and decay times have been analyzed. The required thickness differs drastically depending on the chosen scenario and on the material of the door. The streaming through the gaps around the door is relatively small with high dose rates limited to small sections of the geometry.

43 PARTICLE ACCELERATORS↗
DOE OSTI2017

Calibrations for charged particle tracking and measurements of w photoproduction with the GlueX detector

The GlueX experiment is a new experimental facility at Jefferson Lab in Newport News, VA. The experiment aims to map out the spectrum of hybrid mesons in the light quark sector. Measurements of the spin-density matrix elements in omega photoproduction are performed with a linear polarized photon beam on an unpolarized proton target, and presented in bins of Mandelstam t for beam energies of 8.4-9.0 GeV. The spin-density matrix elements are exclusively measured through two decays of the omega meson: omega -> pi^+ pi^- pi^0 and omega ->pi^0 gamma. A description of the experimental apparatus is presented. Several methods used in the calibration of the charged particle tracking system are described. These measurements greatly improve the world statistics in this energy range. These are the first results measured through the omega ->pi^0 gamma decay at this energy. Results are generally consistent with a theoretical model based on diffractive production with Pomeron and pseudoscalar exchange in the t-channel.

Staib, Michael↗
NASA NTRS1972

Cosmic gamma-rays from pion decay

The production of gamma rays from the decay of neutral pions produced in interstellar cosmic ray interactions was studied, limited to the total gamma ray intensity. Using the upper-limit gamma ray production, an upper-limit is obtained consistent with that obtained by Kraushaar. It is shown that whatever the shape of the gamma ray spectrum, the normalization has to be consistent with data of the total cross sections.

Stecker, F. W.↗
DOE OSTI2019

Properties of the decay ${{H\to\gamma\gamma}} $ using the approximate ${{\alpha_s^4}}$ corrections and the principle of maximum conformality

The decay channel $ H\to\gamma\gamma $ is an important channel for probing the properties of the Higgs boson. In this paper, we analyze its decay width by using the perturbative QCD corrections up to the $ \alpha_s^4 $ order with the help of the principle of maximum conformality (PMC). PMC has been suggested in literature for eliminating the conventional renormalization scheme-and-scale ambiguities. After applying PMC, we observe that an accurate renormalization scale independent decay width $ \Gamma(H\to\gamma\gamma) $ up to the N 4 LO level can be achieved. Taking the Higgs mass, $ M_{\rm H} = 125.09\pm $ $ 0.21\pm0.11 $ GeV, given by the ATLAS and CMS collaborations, we obtain $ \Gamma(H\to \gamma\gamma)|_{\rm LHC} = 9.364^{+0.076}_{-0.075} $ KeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Search for the rare decays $W^+ → D^+_s \gamma$ and $Z → D^0 \gamma$ at LHCb

A search for the rare decays $W^+ → D^+_s \gamma$ and $Z → D^0 \gamma$ is performed using proton-proton collision data collected by the LHCb experiment at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 2.0fb -1 . No significant signal is observed for either decay mode and upper limits on their branching fractions are set using W⁺ → μ⁺v and Z → μ⁺μ⁻ decays as normalization channels. The upper limits are 6.5 x 10 -4 and 2.1 x 10 -3 at 95% confidence level for the $W^+ → D^+_s \gamma$ and $Z → D^0 \gamma$ decay modes, respectively. This is the first reported search for the $Z → D^0 \gamma$ decay, while the upper limit on the branching fraction $W^+ → D^+_s \gamma$ improves upon the previous best limit.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Toward a complete theory for predicting inclusive deuteron breakup away from stability

We present an account of the current status of the theoretical treatment of inclusive (d, p) reactions in the breakup-fusion formalism, pointing to some applications and making the connection with current experimental capabilities. Three independent implementations of the reaction formalism have been recently developed, making use of different numerical strategies. The codes also originally relied on two different but equivalent representations, namely the prior (Udagawa-Tamura, UT) and the post (Ichimura-Austern-Vincent, IAV) representations. The different implementations have been benchmarked for the first time, and then applied to the Ca isotopic chain. The neutron-Ca propagator is described in the Dispersive Optical Model (DOM) framework, and the interplay between elastic breakup (EB) and non-elastic breakup (NEB) is studied for three Ca isotopes at two different bombarding energies. The accuracy of the description of different reaction observables is assessed by comparing with experimental data of (d, p) on 40,48Ca. We discuss the predictions of the model for the extreme case of an isotope (60Ca) currently unavailable experimentally, though possibly available in future facilities (nominally within production reach at FRIB). We explore the use of (d, p) reactions as surrogates for (n,γ) processes, by using the formalism to describe the compound nucleus formation in a (d,pγ) reaction as a function of excitation energy, spin, and parity. The subsequent decay is then computed within a Hauser-Feshbach formalism. Comparisons between the (d,pγ) and (n,γ) induced gamma decay spectra are discussed to inform efforts to infer neutron captures from (d,pγ) reactions. Finally, we identify areas of opportunity for future developments, and discuss a possible path toward a predictive reaction theory.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Spectroscopy and lifetime measurements near the proton drip line: P 26 , 27 , 28

We report on the observation of excited states in the neutron-deficient phosphorus isotopes 26,27,28 P via in-beam gamma-ray spectroscopy with both high-efficiency and high-resolution detector arrays. In 26 P, a previously-unobserved level has been identified at 244(3) keV, two new measurements of the astrophysically-important 3/2 + resonance in 27 P have been performed, gamma decays have been assigned to the proton-unbound levels at 2216 keV and 2483 keV in 28 P, and the gamma-ray lineshape method has been used to make the first determination of the lifetimes of the two lowest-lying excited states in 28P. The expected Thomas-Ehrman shifts were calculated and applied to levels in the mirror nuclei. The resulting level energies from this procedure were then compared with the energies of known states in 26,27,28 P.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Precision Measurement of the Eta Radiative Decay Width via the Primakoff Effect with GlueX

The GlueX detector in the experimental Hall-D at Jefferson Lab provides a unique capability to perform a measurement of the eta to gamma gamma decay width via the Primakoff effect with the precision significantly better than all existing collider and Primakoff results. The experiment will measure differential cross sections of eta mesons at forward angles on a liquid hydrogen and helium targets using a beam of tagged photons, which will be used for the extraction of the decay width. The measurement is essential for the determination of the fundamental properties such as the ratios of the light quark masses and the eta eta-prime mixing angle, and will provide an important test of chiral symmetry breaking in QCD. The experimental results will also allow to significantly reduce uncertainties on partial widths of all other eta decays. We will give an overview the PrimEx-D physics program and experimental setup.

Somov, Alexander↗
DOE OSTI2025

Alpha Decay Chains as Thermal Power Sources: Analysis and Applications for RTGs

Radioactive sources can provide power in remote and environmentally harsh locations such as the arctic or space. The generators powered by such sources are rugged and can withstand extreme temperatures, lack of sunlight, and require no human intervention for multiple years. Radioisotopes are used in thermoelectric generators to provide power at remote sites and deep in space. Isotopes like Pu-238, Cm-244, and Am-241 are used in these generators by NASA for power in space probes and spacecrafts. These power sources deliver a steady supply of energy over extended periods of time. Alpha particles created during decay do not travel far in a material. Their kinetic energy is transferred to heat that we can then convert into energy. Unlike beta and gamma decay, the slower-moving alpha particles stop in the material, making their energy available for use. Energy from these natural decay processes provides a reliable source of power. Spontaneous fission is rare and unreliable, and unlike induced fission processes, alpha decay occurs naturally and does not require external management or ignition. The ideal properties of an isotope for use as a power source depend upon the intended use. For use in an Arctic research base over a period of several years, but less than a decade, an isotope that provides high power output over a shorter lifespan may be the most suitable option. Whereas, for deep space missions where a consistent power source for decades or perhaps more than 100 years is needed that would require a very different isotope. One with a much longer half-life that would provide consistent power throughout that time and survive in that state in for these extended periods of time. These examples represent two extreme sides in terms of time frames. By analyzing the power produced by different radioactive decay processes over time, we can evaluate the suitability of various isotope decay chains for specific uses. Some unstable isotopes undergo a series of radioactive decays, transforming into different isotopes at each step and resulting in a stable isotope. The lists of isotopes in these decay processes are known as decay chains. Some of these chains, illustrated in the figures below, are currently being investigated for use in radioisotope thermoelectric generators (RTGs) designed for a range of operational durations.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

η decay program at GlueX

The GlueX detector in the experimental Hall D at Jefferson Lab was designed to search for gluonic excitations in the spectra of light mesons using photon beams. The detector provides a unique capability to perform a precision measurement of the eta -> gamma gamma decay width via the Primakoff effect (PrimEx D experiment) and study rare decays of eta mesons. Measurement of the eta decay width is essential for the determination of fundamental properties such as the ratios of the light quark masses and the eta - eta' mixing angle, and will provide an important test of chiral symmetry breaking in QCD. The physics of rare eta decays spans from critical tests of chiral perturbation theory to the search for lepto-phobic dark matter candidates. I will give an overview of the ongoing PrimEx D experiment and the physics program of rare eta decays, and discuss GlueX plans for the future.

Somov, A.↗
DOE OSTI2019

Search for rare decays of $\mathrm {Z}$ and Higgs bosons to ${\mathrm {J}/\psi } $ and a photon in proton-proton collisions at $\sqrt{s}$ = 13 $\,\text {TeV}$

Here, a search is presented for decays of $\mathrm {Z}$ and Higgs bosons to a ${\mathrm {J}/\psi } $ meson and a photon, with the subsequent decay of the ${\mathrm {J}/\psi } $ to $\mathrm {\mu ^+}\mathrm {\mu ^-} $ . The analysis uses data from proton-proton collisions with an integrated luminosity of 35.9 $\,\text {fb}^{-1}$ at $\sqrt{s}=13\,\text {TeV} $ collected with the CMS detector at the LHC. The observed limit on the $\mathrm {Z}\rightarrow {\mathrm {J}/\psi } \gamma $ decay branching fraction, assuming that the ${\mathrm {J}/\psi } $ meson is produced unpolarized, is $1.4\times 10^{-6}$ at 95% confidence level, which corresponds to a rate higher than expected in the standard model by a factor of 15. For extreme-polarization scenarios, the observed limit changes from $-13.6$ to $+8.6\%$ with respect to the unpolarized scenario. The observed upper limit on the branching fraction for $\mathrm {H} \rightarrow {\mathrm {J}/\psi } \gamma $ where the ${\mathrm {J}/\psi } $ meson is assumed to be transversely polarized is $7.6\times 10^{-4}$ , a factor of 260 larger than the standard model prediction. The results for the Higgs boson are combined with previous data from proton-proton collisions at $\sqrt{s}=8\,\text {TeV} $ to produce an observed upper limit on the branching fraction for $\mathrm {H} \rightarrow {\mathrm {J}/\psi } \gamma $ that is a factor of 220 larger than the standard model value.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Toward $\nu_{\mu}$CC $\eta$ Meson Cross Sections on Argon in SBND

The modeling of resonant neutrino interactions on argon is critical for achieving precision neutrino oscillation measurements and searching for physics beyond the Standard Model with both DUNE and the Short-Baseline Neutrino Program. Higher mass resonances beyond the $\Delta$(1232) baryon are particularly poorly constrained experimentally, and yet contribute a significant rate in multi-GeV interactions. The measurement of $\eta$(548) meson production from the decay of these resonances provides a unique probe, as well as the opportunity to measure observables sensitive to final state interactions with the nucleus. This poster will present progress towards the measurement of meson production with the Short-Baseline Near Detector (SBND) at Fermilab, leveraging the clean $\eta \rightarrow \gamma \gamma$ decay channel. The large statistics of the SBND dataset will provide high-precision measurements of this channel capable of constraining uncertainties in the modeling of higher order resonant interactions. This analysis further provides important handles on electromagnetic shower reconstruction performance through evaluation of the 548 MeV $\eta$ invariant mass peak.

Antonakis, Alexander [UC, Santa Barbara]↗