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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Demonstration of the neutron tracking capability of NEXT array in time-of-flight measurements to improve energy resolution

Precise neutron-energy measurements are required to probe the nuclear structure effects of neutron-rich nuclei, where β-delayed neutron emission becomes a dominant decay mode. The Neutron dEtector with Xn Tracking (NEXT) array has been designed and constructed to measure β-delayed neutrons with better energy resolution. The new design localizes the neutron interaction position by optically segmenting the detector along the direction of the neutron flight path, reducing the associated uncertainties in the neutron time-of-flight measurements. This significantly improves the energy resolution without losing the necessary detection efficiency. The proof-of-principle and efficiency measurements showed promising results. Herein, this article details the implementation of the neutron tracking capability of NEXT array in time-of-flight measurements.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

New isotope 286 Mc produced in the 243 Am + 48 Ca reaction

In this paper, we present results of the second experiment on the synthesis of Mc isotopes in the 243 Am + 48 Ca reaction performed at the gas-filled separator DGFRS-2 of the SHE Factory at JINR. Here, the new isotope 286 Mc was synthesized, and its half-life of $20^{+98}_{–9}$ ms and α-particle energy of 10.71 ± 0.02 MeV were determined. A 286 Mc α–decay chain was recorded down to the spontaneous fission of 266 Db. The spontaneous fission of 279 Rg was observed for the first time in one of four new decay chains of 287 Mc. The excitation function of the reaction was measured at three 48 Ca energies of 242, 250, and 259 MeV; the latter resulted in the first observation of the 5$\textit{n}$–evaporation channel with a cross section of $0.5^{+1.3}_{–0.4}$ pb. The decay properties of 21 previously known odd–$\textit{Z}$ isotopes were improved. The potential for an electron-capture decay mode is discussed for 288 Mc and 284 Nh isotopes. The half-lives of spontaneously fissioning nuclei produced in the 48 Ca–induced reactions with actinide targets are compared with several theoretical predictions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2023

Measurement of the branching fraction of Ξ c 0 → Λ c + π - at Belle

Based on a data sample of 983 fb -1 collected with the Belle detector at the KEKB asymmetric-energy e + ⁢e - collider, we present the study of the heavy-flavor-conserving decay Ξ$^{0}_{c}$ → Λ$^{+}_{c}$⁢π - with Λ$^{+}_{c}$ reconstructed via its p⁢K - π + decay mode. The branching fraction ratio $\mathscr{B}$⁡(Ξ$^{0}_{c}$ → Λ$^{+}_{c}$⁢π - )/$\mathscr{B}$⁡(Ξ$^{0}_{c}$ → Ξ - π + ) is measured to be 0.38 ±0.04 ±0.04. Combining with the world average value of $\mathscr{B}$(Ξ$^{0}_{c}$ → Ξ - π + ), the branching fraction $\mathscr{B}$⁡(Ξ$^{0}_{c}$ → Λ$^{+}_{c}$⁢π - ) is deduced to be (0.54 ±0.05 ±0.05 ±0.12)%. Here, the uncertainties above are statistical, systematic, and from $\mathscr{B}$⁡(Ξ$^{0}_{c}$ → Ξ - π + ), respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

First measurement of the Q 2 distribution of X⁡(3915) single-tag two-photon production

We report the first measurement of the Q 2 distribution of X⁡(3915) produced by single-tag two-photon interactions. The decay mode used is X⁡(3915) →J/Ψ⁢ω. The covered Q 2 region is from 1.5 (GeV/c) 2 to 10.0 (GeV/c) 2 . We observe 7.9 ± 3.1⁢(stat) ± 1.5⁢(syst) events, where we expect 4.1 ± 0.7 events based on the Q 2 = 0 result from the no-tag two-photon process, extrapolated to higher Q 2 region using the $c\bar{c}$ model of Schuler, Berends, and van Gulik. The shape of the distribution is also consistent with this model; we note that statistical uncertainties are large

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Light new physics in B → K ( * ) ν ν ¯ ?

The study of the rare decays B → K ( * ) ν ν ¯ offers a window into the dynamics operating at the electroweak scale, allowing studies of the Standard Model and searches for heavy new physics. However, the analysis of these decays is also potentially sensitive to the on shell production of new light bosons X through the process B → K ( * ) X . In particular, Belle II has recently measured B + → K + ν ν ¯ , finding a 2.8 σ excess under the assumption of heavy new physics. Since this excess is rather localized in the kaon energy, a fit that includes the decay mode B + → K + X to the kinematic distributions prefers m X ≈ 2 GeV with branching fraction Br [ B → K X ] = ( 8.8 ± 2.5 ) × 10 − 6 and a significance of ≈ 3.6 σ . However, no excess was found in the measurements of B → K ( * ) ν ν ¯ , and a global analysis of the Belle II and data leads to Br [ B → K X ] = ( 5.1 ± 2.1 ) × 10 − 6 with a reduced significance of ≈ 2.4 σ . We then study various simplified dark-flavored models and present a possible UV completion based on a gauged B 3 − L 3 symmetry, highlighting the discovery potential of dedicated searches for B → K ( * ) X at Belle II. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Primary observables for gauge boson collider signals

In this paper, we determine a basis for the on-shell four-point amplitudes V V V V for Standard Model gauge bosons V = W ± , Z , γ , g . Following previous work, this completes the analysis of three- and four-point amplitudes for the Standard Model and could be used for model-independent searches for beyond the Standard Model physics at colliders. Our results include a Lagrangian parametrization for the “primary” amplitudes, where including additional derivatives leads to the Mandelstam “descendant” amplitudes, and upper bounds on the coupling constants from imposing unitarity. We also perform an estimate for the sensitivity for new Z decays at the High-Luminosity LHC, finding that Z → γ ℓ ¯ ℓ could be searched for, but that other decay modes, like Z → ( γ γ γ , γ g g ) , are too small to be discovered after imposing unitarity constraints. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Search for high-mass resonances in final states with a τ-lepton and missing transverse momentum with the ATLAS detector

A search for high-mass resonances decaying into a τ-lepton and a neutrino using proton-proton collisions at a center-of-mass energy of $\sqrt{s}$ =13 TeV is presented. The full run 2 data sample corresponding to an integrated luminosity of 139 fb -1 recorded by the ATLAS experiment in the years 2015–2018 is analyzed. The τ-lepton is reconstructed in its hadronic decay modes and the total transverse momentum carried out by neutrinos is inferred from the reconstructed missing transverse momentum. The search for new physics is performed on the transverse mass between the τ-lepton and the missing transverse momentum. No excess of events above the Standard Model expectation is observed and upper exclusion limits are set on the W' →τ⁢v production cross section. Heavy W' vector bosons with masses up to 5.0 TeV are excluded at 95% confidence level, assuming that they have the same couplings as the Standard Model W boson. For nonuniversal couplings, W' bosons are excluded for masses less than 3.5–5.0 TeV, depending on the model parameters. In addition, model-independent limits on the visible cross section times branching ratio are determined as a function of the lower threshold on the transverse mass of the τ-lepton and missing transverse momentum.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Search for baryon and lepton number violating decays D → p ℓ

We search for the baryon and lepton number violating charm decays, D → p ℓ , where D is either a D 0 or a D ¯ 0 and ℓ is a muon or an electron, using a data sample of 921 fb − 1 collected by the Belle detector at the KEKB asymmetric energy e + e − collider. In the absence of significant signals, we set upper limits on the branching fractions in the range ( 5 – 8 ) × 10 − 7 at a 90% confidence level, depending on the decay mode. Published by the American Physical Society 2024

Astronomy & Astrophysics↗
DOE OSTI2024

Searching for axions with kaon decay at rest

We describe a novel search strategy for axions (or hadronically coupled axionlike particles) in the mass range of m a ≲350 MeV. The search relies on kaon decay at rest, which produces a monoenergetic signal in a large volume detector (e.g., a tank of liquid scintillator) from axion decays a → γγ or a → e + ⁢e – . The decay modes K + → π + ⁢a and a → γγ are induced by the axion’s coupling to gluons, which is generic to any model which addresses the strong CP problem. We recast a recent search from MicroBooNE for e +⁢ e – pairs and study prospects at JSNS 2 and other near-term facilities. We find that JSNS 2 will have world-leading sensitivity to hadronically coupled axions in the mass range of 40 MeV ≲ m a ≲ 350 MeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Observation of the J / ψ → μ + μ − μ + μ − decay in proton-proton collisions at s = 13 TeV

The J / ψ → μ + μ − μ + μ − decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of 33.6 fb − 1 . Normalizing to the J / ψ → μ + μ − decay mode leads to a branching fraction of [ 10.1 − 2.7 + 3.3 ( stat ) ± 0.4 ( syst ) ] × 10 − 7 , a value that is consistent with the standard model prediction. © 2024 CERN, for the CMS Collaboration 2024 CERN

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Search for prompt production of pentaquarks in charm hadron final states

A search for hidden-charm pentaquark states decaying to a range of Σ c D ¯ and Λ c + D ¯ final states, as well as doubly charmed pentaquark states to Σ c D and Λ c + D , is made using samples of proton-proton collision data corresponding to an integrated luminosity of 5.7 fb − 1 recorded by the LHCb detector at s = 13 TeV . Since no significant signals are found, upper limits are set on the pentaquark yields relative to that of the Λ c + baryon in the Λ c + → p K − π + decay mode. The known pentaquark states are also investigated, and their signal yields are found to be consistent with zero in all cases. © 2024 CERN, for the LHCb Collaboration 2024 CERN

Aaij, R. (ORCID:0000000305331952)↗
DOE OSTI2024

Search for the baryon number and lepton number violating decays τ − → Λ π − and τ − → Λ ¯ π − at Belle II

We present a search for the baryon number B and lepton number L violating decays τ − → Λ π − and τ − → Λ ¯ π − produced from the e + e − → τ + τ − process, using a 364 fb − 1 data sample collected by the Belle II experiment at the SuperKEKB collider. No evidence of signal is found in either decay mode, which have | Δ ( B − L ) | equal to 2 and 0, respectively. Upper limits at 90% credibility level on the branching fractions of τ − → Λ π − and τ − → Λ ¯ π − are determined to be 4.7 × 10 − 8 and 4.3 × 10 − 8 , respectively. Published by the American Physical Society 2024

Adachi, I. (ORCID:0000000322870173)↗
DOE OSTI2025

Combination of searches for singly produced vectorlike top quarks in 𝑝⁢𝑝 collisions at $\sqrt{𝑠}$ =13 TeV with the ATLAS detector

A combination of searches for the single production of vectorlike top quarks (𝑇) is presented. These analyses are based on proton-proton collisions at $\sqrt{𝑠}$ = 13 TeV recorded in 2015–2018 with the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb −1 . The 𝑇 decay modes considered in this combination are into a top quark and either a Standard Model Higgs boson or a 𝑍 boson (𝑇 → 𝐻⁡𝑡 and 𝑇 → 𝑍⁢𝑡). The individual searches used in the combination are differentiated by the number of leptons (𝑒, 𝜇) in the final state. The observed data are found to be in good agreement with the Standard Model background prediction. Interpretations are provided for a range of masses and couplings of the vectorlike top quark for benchmark models and generalized representations in terms of 95% confidence level limits. For a benchmark signal prediction of a vectorlike top quark SU(2) singlet with electroweak coupling, 𝜅, of 0.5, masses below 2.1 TeV are excluded, resulting in the most restrictive limits to date.

Composite models↗
DOE OSTI2023

Measurement of the Ratios of Branching Fractions R ( D * ) and R ( D 0 )

The ratios of branching fractions $R(D*)$ ≡ $B(\overline{B} → D*τ^-\overline{ν}_μ$)/$B$($\overline{B}$ → $D*μ^-\overline{ν}_μ$) and $R$($D$ 0 ) ≡ $B$($B$ - → $D^0τ^-\overline{v}_τ$)/$B$($B$ - → $D^0μ^-\overline{v}_μ$) are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb -1 of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode $τ^-$ → $μ^-ν_τ\overline{ν}_μ$. The measured values are $R$($D$*) = 0.281 ± 0.018 ± 0.024 and $R$($D$ 0 ) = 0.441 ± 0.060 ± 0.066, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is $ρ$ = -0.43. The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

$K^{*}(892)^0$ meson production in inelastic p+p interactions at 40 and 80 $\text{ GeV }\!/\!c$ beam momenta measured by NA61/SHINE at the CERN SPS

Measurements of $K^{*}(892)^0$ resonance production via its $K^{+}\pi ^{-}$ decay mode in inelastic p+p collisions at beam momenta 40 and 80 $\text{ GeV }\!/\!c$ ($\sqrt{s_{NN}}=8.8$ and 12.3 $\text{ GeV }$) are presented. The data were recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The template method was used to extract the $K^{*}(892)^0$ signal. Transverse momentum and rapidity spectra were obtained. The mean multiplicities of $K^{*}(892)^0$ mesons were found to be $(35.1 \pm 1.3 \mathrm {(stat)} \pm 3.6 \mathrm {(sys))} \cdot 10^{-3}$ at 40 $\text{ GeV }\!/\!c$ and $(58.3 \pm 1.9 \mathrm {(stat)} \pm 4.9 \mathrm {(sys))} \cdot 10^{-3}$ at 80 $\text{ GeV }\!/\!c$. The NA61/SHINE results are compared with the Epos1.99 and Hadron Resonance Gas models as well as with world data. The transverse mass spectra of $K^{*}(892)^0$ mesons and other particles previously reported by NA61/SHINE were fitted within the Blast-Wave model. The transverse flow velocities are close to 0.1–0.2 of the speed of light and are significantly smaller than the ones determined in heavy nucleus-nucleus interactions at the same beam momenta.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Underlying-event studies with strange hadrons in pp collisions at √s = 13 TeV with the ATLAS detector

Properties of the underlying-event in pp interactions are investigated primarily via the strange hadrons $K^0_S$, $\Lambda$, and $\bar\Lambda$, as reconstructed using the ATLAS detector at the LHC in minimum-bias pp collision data at √s = 13 TeV. The hadrons are reconstructed via the identification of the displaced two-particle vertices corresponding to the decay modes $K^0_S$ → π⁺π⁻, Λ → π⁻p and $\bar\Lambda$ → $\pi^+\overline{p}$. These are used in the construction of underlying-event observables in azimuthal regions computed relative to the leading charged-particle jet in the event. None of the hadronisation and underlying-event physics models considered can describe the data over the full kinematic range considered. Events with a leading charged-particle jet in the range of 10 < p T ≤ 40 GeV are studied using the number of prompt charged particles in the transverse region. The ratio N(Λ + $\bar\Lambda$/N($K^0_S$) as a function of the number of such charged particles varies only slightly over this range. This disagrees with the expectations of some of the considered Monte Carlo models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Sustainable production of radionuclidically pure antimony-119

Background Radiopharmaceutical therapy (RPT) uses radionuclides that decay via one of three therapeutically relevant decay modes (alpha, beta, and internal conversion (IC) / Auger electron (AE) emission) to deliver short range, highly damaging radiation inside of diseased cells, maintaining localized dose distribution and sparing healthy cells. Antimony-119 ( 119 Sb, t 1/2 = 38.19 h, EC = 100%) is one such IC/AE emitting radionuclide, previously limited to in silico computational investigation due to barriers in production, chemical separation, and chelation. A theranostic (therapeutic/diagnostic) pair can be formed with 119 Sb’s radioisotopic imaging analogue 117 Sb (t 1/2 = 2.80 h, E γ = 158.6 keV, I γ = 85.9%, β + = 262.4 keV, I β+ = 1.81%). Results Within, we report techniques for sustainable and cost-effective production of pre-clinical quality and quantity, radionuclidically pure 119 Sb and 117 Sb, novel low energy photon measurement techniques for 119 Sb activity determination, and physical yields for various tin target isotopic enrichments and thicknesses using (p, n) and (d, n) nuclear reactions. Additionally, we present a two-column separation providing a radioantimony yield of 73.1% ± 6.9% (N = 3) and tin separation factor of (6.8 ± 5.5) x 10 5 (N = 3). Apparent molar activity measurements for deuteron produced 117 Sb using the chelator TREN-CAM were measured at 42.4 ± 25 MBq 117 Sb/µmol (1.14 ± 0.68 mCi/µmol), and we recovered enriched 119 Sn target material at a recycling efficiency of 80.2% ± 5.5% (N = 6) with losses of 11.6 mg ± 0.8 mg (N = 6) per production. Conclusion We report significant steps in overcoming barriers in 119 Sb production, chemical isolation and purification, enriched target material recycling, and chelation, helping promote accessibility and application of this promising therapeutic radionuclide. We describe a method for 119 Sb activity measurement using its low energy gamma (23.87 keV), negating the need for attenuation correction. Finally, we report the largest yet-measured 119 Sb production yields using proton and deuteron irradiation of natural and enriched targets and radioisotopic purity > 99.8% at end of purification.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2022

Standardizing a Renewed Fission Product Yield Library and Related Covariances (Part II)

A complete library of independent fission product yields including covariance information was generated by a sequential Bayesian methodology whose prior information consisted of independent fission product yields and branching ratios of the possible decay modes reported in the recently released ENDF/B-VIII.0 nuclear data library. The Bayesian procedure consisted in the adjustment of independent fission product yields to match the set of stable and long-lived cumulative yields reported in the ENDF/B-VIII.0 nuclear data library which, in this work, were considered as legacy values together with their uncertainties. According to the χ 2 -metric, the results obtained by this methodology show a systematic improvement in the agreement with legacy reported cumulative yields for the entire adjusted independent fission product yield library.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗