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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

High-Statistics Measurement of Neutrino Quasielasticlike Scattering at 6 GeV on a Hydrocarbon Target

We measure neutrino charged-current quasielasticlike scattering on hydrocarbon at high statistics using the wideband Neutrinos at the Main Injector beam with neutrino energy peaked at 6 GeV. The double-differential cross section is reported in terms of muon longitudinal ( p ∥ ) and transverse ( p ⊥ ) momentum. Cross section contours versus lepton momentum components are approximately described by a conventional generator-based simulation, however, discrepancies are observed for transverse momenta above 0.5 GeV / c for longitudinal momentum ranges 3–5 and 9 – 20 GeV / c . The single differential cross section versus momentum transfer squared ( d σ / d Q QE 2 ) is measured over a four-decade range of Q 2 that extends to 10 GeV 2 . The cross section turnover and falloff in the Q 2 range 0.3 – 10 GeV 2 is not fully reproduced by generator predictions that rely on dipole form factors. Our measurement probes the axial-vector content of the hadronic current and complements the electromagnetic form factor data obtained using electron-nucleon elastic scattering. These results help oscillation experiments because they probe the importance of various correlations and final-state interaction effects within the nucleus, which have different effects on the visible energy in detectors.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

A substandard candle: the low-$$\nu $$ method at few-GeV neutrino energies

Abstract As accelerator-based neutrino oscillation experiments improve oscillation parameter constraints with more data, control over systematic uncertainties on the incoming neutrino flux and interaction models is increasingly important. The intense beams offered by modern experiments permit a variety of options to constrain the flux using in situ “standard candle” measurements. These standard candles must use very well understood interaction processes to avoid introducing additional interaction model dependence. One option often discussed in this context is the “low- $$\nu $$ ν ” method, which is designed to isolate neutrino interactions where there is low energy-transfer to the nucleus, such that the interaction cross section is expected to be approximately constant as a function of neutrino energy. The shape of the low-energy transfer event sample can then be used to extract the flux shape. Applications of the method at high neutrino energies (many tens of GeV) are well understood. However, the applicability of the method at the lower energies of current and future few-GeV accelerator neutrino experiments remains unclear due to the presence of nuclear and form-factor effects inherent in the interaction models.In this analysis we examine the prospects for improving constraints on the accelerator neutrino fluxes in situ with the low- $$\nu $$ ν method in an experiment-independent way, using (anti)neutrino interactions on argon and hydrocarbon targets from the GENIE, NEUT, NuWro and GiBUU event generators. We begin by investigating the extent to which deviations from the constant cross-section assumption are dependent on poorly understood aspects of the neutrino interaction model. We then assess whether a low energy-transfer event sample can be confidently identified using experimentally accessible observables. We finally consider how the practicalities of reconstructing the energy spectrum of interacting neutrinos in realistic detectors might further limit the utility of low- $$\nu $$ ν flux constraints. The results show that flux constraints from the low- $$\nu $$ ν method would be severely dependent on the interaction model assumptions used in an analysis of neutrinos with energies below 5 GeV, and anti-neutrinos below at least 15 GeV. The spread of model predictions show that a low- $$\nu $$ ν analysis is unlikely to offer much improvement on typical neutrino flux uncertainties, even with a perfect detector. Notably—running counter to the assumption inherent to the low- $$\nu $$ ν method—the model-dependence increases with decreasing energy transfer for experiments in the few-GeV region.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

An 8 GeV Linac as the Booster Replacement in the Fermilab Power Upgrade

Increasing the Main Injector (MI) beam power above ~1.2 MW requires replacement of the 8 GeV Booster by a higher intensity alternative. Previously, rapid-cycling synchrotron (RCS) and Linac solutions were considered for this purpose. In this paper, we consider the Linac version that produces 8 GeV H⁻ beam for injection into the Recycler Ring (RR) or Main Injector (MI). The Linac takes ~1 GeV beam from the PIP-II Linac and accelerates it to ~2 GeV in a cw SRF linac, followed by a ~2-8 GeV pulsed linac using 1300 MHz cryomodules. The linac components incorporate recent improvements in SRF technology. The linac configuration and beam dynamics requirements are presented. Injection options are discussed. Research needed to implement the Booster replacement is described.

Neuffer, David V.↗
DOE OSTI2021

An 8 GeV Linac as the Booster Replacement in the Fermilab Power Upgrade

Increasing the Main Injector (MI) beam power above ~1.2 MW requires replacement of the 8 GeV Booster by a higher intensity alternative. In the Project X era, rapid-cycling synchrotron (RCS) and Linac solutions were considered for this purpose. In this paper, we consider the Linac version that produces 8 GeV H- beam for injection into the Recycler Ring(RR) or Main Injector (MI). The Linac takes ~1 GeV beam from the PIP-II Linac and accelerates it to ~2 GeV in a 650MHz SRF Linac, followed by a ~2-8 GeV pulsed Linac using 1300 MHz cryomodules. The Linac components incorporate recent improvements in SRF technology. The Linac configuration and beam dynamics requirements are presented. Injection options are discussed. Foil-based injection is the present standard but R&D toward implementing laser-assisted injection could enable a significant improvement. Research needed to implement the Booster replacement is described.

42 ENGINEERING↗
DOE OSTI2016

The first GeV outburst of the radio-loud narrow-line Seyfert 1 galaxy PKS 1502+036

The γ-ray-loud narrow-line Seyfert 1 (γ-NLSy1) galaxy PKS 1502+036 (z = 0.409) exhibited its first γ-ray outburst on 2015 December 20. In the energy range of 0.1–300 GeV, the highest flux measured by the Fermi-Large Area Telescope is (3.90 ± 1.52) × 10{sup −6} ph cm{sup −2} s{sup −1}, which is the highest γ-ray flux ever detected from this object. The associated spectral shape is soft (Γ{sub 0.1–300 GeV} = 2.57 ± 0.17) and this corresponds to an isotropic γ-ray luminosity of (1.2 ± 0.6) × 10{sup 48} erg s{sup −1}. We generate the broadband spectral energy distribution (SED) during the GeV flare and reproduce it using a one-zone leptonic emission model. The optical-UV spectrum can be explained by a combination of synchrotron and accretion disk emission, whereas the X-ray-to-γ-ray SED can be satisfactorily reproduced by inverse-Compton scattering of thermal photons that originated from the torus. The derived SED parameters hint that the increase in the bulk Lorentz factor is a major cause of the flare and the location of the emission region is estimated as being outside the broad-line region but still inside the torus. A comparison of the GeV-flaring SED of PKS 1502+036 with that of two other γ-NLSy1 galaxies, namely, 1H 0323+342 (z = 0.061) and PMN J0948+0022 (z = 0.585), and also with flat spectrum radio quasar (FSRQ) 3C 279 (z = 0.536), has led to the conclusion that the GeV-flaring SEDs of γ-NLSy1 galaxies resemble FSRQs and a major fraction of their bolometric luminosities are emitted at γ-ray energies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Early Commissioning Experience and Future Plans for the 12 GeV Continuous Electron Beam Accelerator Facility

Jefferson Lab has recently completed the accelerator portion of the 12 GeV Upgrade for the Continuous Electron Beam Accelerator Facility. All 52 SRF cryomodules have been commissioned and operated with beam. The initial beam transport goals of demonstrating 2.2 GeV per pass, greater than 6 GeV in 3 passes to an existing experimental facility and greater than 10 GeV in 5-1/2 passes have all been accomplished. These results along with future plans to commission the remaining beamlines and to increase the performance of the accelerator to achieve reliable, robust and efficient operations at 12 GeV are presented.

Spata, Michael F.↗
DOE OSTI2021

An 8 GEV Linac As The Booster Replacement In The Fermilab Power Upgrade

Increasing the Fermilab Main Injector (MI) beam power above ~1.2 MW requires replacement of the 8 GeV Booster by a higher intensity alternative. Earlier, rapid-cycling synchrotron and linac solutions were considered for this purpose. In this paper, we consider the linac version that produces 8 GeV H- beam for injection into the Recycler Ring (RR) or MI The new linac takes ~1 GeV beam from the PIP-II linac and accelerates it to ~ 2 GeV in a 650 MHz SRF linac, and then accelerates to ~8 GeV in an SRF pulsed linac using 1300 MHz cryomodules. The linac components incorporate recent improvements in SRF technology. This Booster Replacement linac (BRL) will increase MI beam power to DUNE to more than 2.5 MW and enable next-generation intensity frontier experiments.

Neuffer, David V.↗
DOE OSTI2016

Design of 3 GeV booster ring lattice

The aim of this study is to design of a 3 GeV booster ring for the 3 GeV storage ring. Electrons are needed to be accelerated to 3.0 GeV from 0.15 GeV energy. In this frame, we studied on two options for booster ring; a compact booster and the booster that shares the same tunnel with the storage ring. The lattice type has been chosen FODO for both options, lattice parameters are calculated, sextupole magnets are used to decrease dynamic aperture problem and dynamic aperture calculations are also made with considering of the necessary conditions. After designing and calculating of the parameters, these designs have been compared with each other. In addition to this comparison, these booster design parameters have been compared with some world centers design parameters and the reliability of the booster design is seen. Beam optics, OPA and Elegant simulation programs have been used in the study calculations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

The star-forming galaxy contribution to the cosmic MeV and GeV gamma-ray background

Star-forming galaxies could be major contributors to the cosmic GeV γ-ray background, and they are expected to be MeV-dim because of the 'pion bump' falling off below ∼100 MeV. However, there are very few observations of galaxies in the MeV range and other emission processes could be present. We investigate the MeV background from star-forming galaxies by running one-zone models of cosmic ray populations, including inverse Compton and bremsstrahlung, as well as nuclear lines (including {sup 26}Al), emission from core-collapse supernovae, and positron annihilation emission, in addition to the pionic emission. We use the Milky Way and M82 as templates of normal and starburst galaxies and compare our models to radio and GeV-TeV γ-ray data. We find that (1) higher gas densities in high-z normal galaxies lead to a strong pion bump, (2) starbursts may have significant MeV emission if their magnetic field strengths are low, and (3) cascades can contribute to the MeV emission of starbursts if they emit mainly hadronic γ-rays. Our fiducial model predicts that most of the unresolved GeV background is from star-forming galaxies, but this prediction is uncertain by an order of magnitude. About ∼2% of the claimed 1 MeV background is diffuse emission from star-forming galaxies; we place a firm upper limit of ≲ 10% based on the spectral shape of the background. The star formation contribution is constrained to be small because its spectrum is peaked, while the observed background is steeply falling with energy through the MeV-GeV range.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Search for GeV gamma-ray bursts with the ARGO-YBJ detector: summary of eight years of observations

The search for gamma-ray burst (GRB) emission in the energy range of 1-100 GeV in coincidence with the satellite detection has been carried out using the Astrophysical Radiation with Ground-based Observatory at YangBaJing (ARGO-YBJ) experiment. The high-altitude location (4300 m a.s.l.), the large active surface (∼6700 m{sup 2} of Resistive Plate Chambers), the wide field of view (∼2 sr, limited only by the atmospheric absorption), and the high duty cycle (>86%) make the ARGO-YBJ experiment particularly suitable to detect short and unexpected events like GRBs. With the scaler mode technique, i.e., counting all the particles hitting the detector with no measurement of the primary energy and arrival direction, the minimum threshold of ∼1 GeV can be reached, overlapping the direct measurements carried out by satellites. During the experiment lifetime from 2004 December 17 to 2013 February 7, a total of 206 GRBs occurring within the ARGO-YBJ field of view (zenith angle θ ≤ 45°) have been analyzed. This is the largest sample of GRBs investigated with a ground-based detector. Two light curve models have been assumed and since in both cases no significant excess has been found, the corresponding fluence upper limits in the 1-100 GeV energy region have been derived, with values as low as 10{sup –5} erg cm{sup –2}. The analysis of a subset of 24 GRBs with known redshift has been used to constrain the fluence extrapolation to the GeV region together with possible cutoffs under different assumptions on the spectrum.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Experimental constraints on γ-ray pulsar gap models and the pulsar GeV to pulsar wind nebula TeV connection

The pulsar emission mechanism in the gamma ray energy band is poorly understood. Currently, there are several models under discussion in the pulsar community. These models can be constrained by studying the collective properties of a sample of pulsars, which became possible with the large sample of gamma ray pulsars discovered by the Fermi Large Area Telescope. In this paper we develop a new experimental multi-wavelength technique to determine the beaming factor (f{sub Ω}) dependance on spin-down luminosity of a set of GeV pulsars. This technique requires three input parameters: pulsar spin-down luminosity, pulsar phase-averaged GeV flux, and TeV or X-ray flux from the associated pulsar wind nebula (PWN). The analysis presented in this paper uses the PWN TeV flux measurements to study the correlation between f{sub Ω} and E-dot . The measured correlation has some features that favor the Outer Gap model over the Polar Cap, Slot Gap, and One Pole Caustic models for pulsar emission in the energy range of 0.1–100 GeV, but one must keep in mind that these simulated models failed to explain many of the most important pulsar population characteristics. A tight correlation between the pulsar GeV emission and PWN TeV emission was also observed, which suggests the possibility of a linear relationship between the two emission mechanisms. In this paper we also discuss a possible mechanism to explain this correlation.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

On the location of the 2009 GeV flares of blazar PKS 1510–089

Most of the radiated power of blazars is produced at GeV energies via inverse Compton scattering at an unknown distance from the central engine. Possible seed photon sources map to different locations along the jet spanning two orders of magnitude in distance from the black hole, ranging from the broad-line region (BLR, ∼0.1 pc), to the molecular torus (MT, ∼1− few pc), to the very long baseline interferometry (VLBI) radio core zone at ∼10 pc. Here, we apply a diagnostic for identifying the GeV emission zone (GEZ) in blazar PKS 1510–089 using four bright gamma-ray flares detected by Fermi in 2009. As shown by Dotson et al., the flare decay time should be energy-independent for flares in the BLR, but faster at higher energies for flares in the MT. We find that in the two cases where the gamma-ray flare was not accompanied by an optical flare, the decay times show an energy-dependence suggesting a location in the MT. For the two GeV flares accompanied by optical flares, we obtained very fast decay times (≲3 hr) in both low and high energy Fermi bands. For these flares, considering the simultaneous >100 GeV detection by HESS (H.E.S.S. Collaboration et al.) and the ejection of a superluminal component from the VLBI radio core in one case, our results suggest that both flares came from the vicinity of the VLBI core. We thus suggest that the GEZ is spread over a wide range of locations beyond the BLR.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

A 130 GeV photon line from dark matter annihilation in the NMSSM

In the Next-to-Minimal Supersymmetric Standard Model, neutralino dark matter can annihilate into a pair of photons through the exchange of a CP-odd Higgs boson in the s-channel. The CP-odd Higgs boson couples to two photons through a loop of dominantly higgsino-like charginos. We show that the parameter space of the NMSSM can accommodate simultaneously i) neutralino-like dark matter of a mass of about 130 GeV giving rise to a 130 GeV photon line; ii) an annihilation cross section of or larger than 10{sup −27} cm{sup 3} s{sup −1}; iii) a relic density in agreement with WMAP constraints; iv) a direct detection cross section compatible with bounds from XENON100, and v) a Standard Model like Higgs mass of about 125 GeV. However, the CP-odd Higgs mass has to lie accidentally close to 260 GeV.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2012

Constraints on the dark matter annihilation scenario of Fermi 130 GeV gamma-ray line emission by continuous gamma-rays, Milky Way halo, galaxy clusters and dwarf galaxies observations

It was recently reported that there may exist monochromatic γ-ray emission at ∼ 130 GeV from the Galactic center in the Fermi Large Area Telescope data, which might be related with dark matter (DM) annihilation. In this work we carry out a comprehensive check of consistency of the results with the DM annihilation scenario, using the 3.7 yrs Fermi observation of the inner Galaxy, Galactic halo, clusters of galaxies and dwarf galaxies. The results found are as follows. 1) Very strong constraints on the DM annihilation into continuous γ-rays from the Galactic center are set, which are as stringent as the 'natural' scale assuming thermal freeze-out of DM. Such limit sets strong constraint on the DM models to explain the line emission. 2) No line emission from the Galactic halo is found in the Fermi data, (and the constraints on line emission is marginally consistent with) the DM annihilation interpretation of the ∼ 130 GeV line emission from the inner Galaxy. 3) No line emission from galaxy clusters and dwarf galaxies is detected, although possible concentration of photons from clusters in 120–140 GeV is revealed. The constraints from clusters and dwarf galaxies are weak and consistent with the DM annihilation scenario to explain the ∼ 130 GeV line emission.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Heavy scalar boson in view of the unconfirmed 750 GeV LHC diphoton excess

We discuss the impact of the constraints from the measurements of the parameters of the observed 125 GeV Higgs boson and from the unconfirmed 750 GeV diphoton excess in the LHC experiments on the properties of a possible extra scalar boson predicted in various Standard Model extensions. We consider an SM extension based on a stabilized brane-world model, in which the effective low-energy Lagrangian for the scalar degrees of freedom turns out to be very general and, for different values of the model parameters, reproduces the scalar field Lagrangians of various SM extensions by a singlet scalar. It is shown that in the simplest variant of the model, where only the gravitational degrees of freedom propagate in the bulk, the 125 GeV scalar state can be consistently interpreted as a Higgs-dominated state for a rather wide range of the model parameters, whereas the production cross section of a heavier radion-dominated state with mass 750 GeV or more turns out to be too small in the allowed region of the model parameter space for producing the wouldbe diphoton excess.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

GeV Detection of HESS J0632+057

HESS J0632+057 is the only gamma-ray binary that has been detected at TeV energies, but not at GeV energies yet. Based on nearly nine years of Fermi Large Area Telescope (LAT) Pass 8 data, we report here on a deep search for the gamma-ray emission from HESS J0632+057 in the 0.1–300 GeV energy range. We find a previously unknown gamma-ray source, Fermi J0632.6+0548, spatially coincident with HESS J0632+057. The measured flux of Fermi J0632.6+0548 is consistent with the previous flux upper limit on HESS J0632+057 and shows variability that can be related to the HESS J0632+057 orbital phase. We propose that Fermi J0632.6+0548 is the GeV counterpart of HESS J0632+057. Considering the Very High Energy spectrum of HESS J0632+057, a possible spectral turnover above 10 GeV may exist in Fermi J0632.6+0548, as appears to be common in other established gamma-ray binaries.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Search for a very light NMSSM Higgs boson produced in decays of the 125 GeV scalar boson and decaying into $\tau$ leptons in pp collisions at $\sqrt{s} =$ 8 TeV

Our search for a very light Higgs boson decaying into a pair of t leptons is presented within the framework of the next-to-minimal supersymmetric standard model. This search is based on a data set corresponding to an integrated luminosity of 19.7 fb -1 of proton-proton collisions collected by the CMS experiment at a centre-of-mass energy of 8 TeV. The signal is defined by the production of either of the two lightest scalars, h 1 or h 2 , via gluon-gluon fusion and subsequent decay into a pair of the lightest Higgs bosons, a 1 or h 1 . The h 1 or h 2 boson is identified with the observed state at a mass of 125 GeV. The analysis searches for decays of the a 1 (h 1 ) states into pairs of t leptons and covers a mass range for the a 1 (h 1 ) boson of 4 to 8 GeV. Furthermore, the search reveals no significant excess in data above standard model background expectations, and an upper limit is set on the signal production cross section times branching fraction as a function of the a 1 (h 1 ) boson mass. The 95% confidence level limit ranges from 4.5 pb at ma 1 (mh 1 ) = 8 GeV to 10.3 pb at ma 1 (mh 1 ) = 5 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Measurement of e + e − → ωπ+π− cross section at $\sqrt{s}$ = 2.000 to 3.080 GeV

A partial wave analysis on the process e⁺e⁻ → ωπ⁺π⁻ is performed using 647 pb -1 of data sample collected by using the BESIII detector operating at the BEPCII storage ring at center-of-mass (c.m.) energies from 2.000 GeV to 3.080 GeV. The Born cross section of the e⁺e⁻ → ωπ⁺π⁻ process is measured, with precision improved by a factor of 3 compared to that of previous studies. A structure near 2.25 GeV is observed in the energy-dependent cross sections of e⁺e⁻ → ωπ⁺π⁻ and ωπ 0 π 0 with a statistical significance of 7.6σ, and its determined mass and width are 2232 ± 19 ± 27 MeV/c 2 and 93 ± 53 ± 20 MeV, respectively, where the first and second uncertainties are statistical and systematic, respectively. By analyzing the cross sections of subprocesses e⁺e⁻ → ωf 0 (500), ωf 0 (980), ωf 0 (1370), ωf 2 (1270), and b1(1235)π, a structure, with mass M = 2200 ± 11 ± 17 MeV/c 2 and width Γ = 74 ± 20 ± 24 MeV, is observed with a combined statistical significance of 7.9σ. The measured resonance parameters will help to reveal the nature of vector states around 2.25 GeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗