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Makoto Sakuda

Publications and source records attributed to Makoto Sakuda.

18 recordsLinked to original sources
arXiv2024

Study of the neutrino-oxygen cross sections of the charged-current reaction 16O($\barν_e,e^+$)16N(0 MeV,$2^-$) and the neutral-current reaction 16O($ν,ν$')16O(12.97/12.53 MeV,$2^-$), producing high-energy gamma rays

In the previous work, we discussed the cross section and the detection of 4.4-MeV $γ$ rays produced in the neutrino neutral-current (NC) reaction $^{16}$O($ν, ν^{\prime}$)$^{16}$O(12.97 MeV and 12.53 MeV, $2^-$) in a water Cherenkov detector at the low energy below 100 MeV. In this report, we further investigated both the charged-current (CC) reaction $^{16}$O($\barν_e, e^+$)$^{16}$N(0 MeV, $2^-$) and the NC reaction$^{16}$O($ν, ν^{\prime}$)$^{16}$O(12.97 MeV and 12.53 MeV, $2^-$), producing high-energy $γ$ rays, in which the more solid identification of the reactions can be applied via the coincidence method.

nucl-th↗
arXiv2024

Determination of the proton spectral function of \isotope[12][]{C} from $(e,e^\prime p)$ data

The determination of the nuclear spectral function from the measured cross section of the electron-nucleus scattering process $e + A \to e^\prime + p + (A-1)$is discussed, and illustrated for the case of a carbon target. The theoretical model based on the local density approximation, previously employed to derive the spectral function from a combination of accurate theoretical calculations and experimental data, has been developed further by including additional information obtained from measurements performed with high missing energy resolution. The implications for the analysis of $γ$-ray emission associated with nuclear deexcitation are considered.

nucl-th↗
arXiv2023

Neutrino-induced reactions on 18O and implications of 18O mixture in water Cherenkov detectors on supernova neutrino events

Neutrino-nucleus reaction cross sections on 18O are evaluated by shell-model calculations and compared with those on 16O. Important contributions from Gamow-Teller transitions are noticed for 18O (ν_e, e^{-})18F in contrary to the case for 16O, where spin-dipole transitions are dominant contributions. Calculated cross sections for 18O(ν_e, e^{-})18F are shown to be larger than for 16O at low neutrino energies below 20 MeV in natural water with the 0.205% admixture of 18O due to the lower threshold energy (1.66 MeV) for 18O than that for 16O (15.42 MeV). The resulting electron spectra, that is, the cross sections as functions of emitted electron energy Te, are also shown to be quite different, reflecting the different threshold energies. The electron spectra from (ν_e, e^{-}) reactions on 18O and 16O in water Cherenkov detectors for supernova neutrino detection are investigated for both the cases with and without the neutrino oscillation and compared with those of the neutrino-electron scattering. It has been shown that the contribution from 18O (0.205% mixture) enhances the rates from 16O by 60% for the case without the oscillation and by 20-30% for the case with the oscillation below Te =20 MeV. For the case with the neutrino oscillation, the event rates for 18O and 16O become comparable to those of the neutrino-electron scattering. However, their rates at low energy (Te < 20 MeV) are much smaller than those of the neutrino-electron scattering, which is important for the pointing accuracy to the supernova direction.

nucl-th↗
arXiv2023

Angular correlation of the two gamma rays produced in the thermal neutron capture on gadolinium-155 and gadolinium-157

The ANNRI-Gd collaboration studied in detail the single $γ$-ray spectrum produced from the thermal neutron capture on $^{155}$Gd and $^{157}$Gd in our previous publications. Gadolinium targets were exposed to a neutron beam provided by the Japan Spallation Neutron Source (JSNS) in J-PARC, Japan. In the present analysis, one new additional coaxial germanium crystal was used in the analysis in combination with the fourteen germanium crystals in the cluster detectors to study the angular correlation of the two $γ$ rays emitted in the same neutron capture. We present for the first time angular correlation functions for two $γ$ rays produced during the electromagnetic cascade transitions in the (n, $γ$) reactions on $^{\rm 155}$Gd and $^{\rm 157}$Gd. As expected, we observe the mild angular correlations for the strong, but rare transitions from the resonance state to the two energy levels of known spin-parities. Contrariwise, we observe negligibly small angular correlations for arbitrary pairs of two $γ$ rays produced in the majority of cascade transitions from the resonance state to the dense continuum states.

nucl-ex↗
arXiv2022

Detection of the 4.4-MeV gamma rays from $^{16}$O($ν, ν^{\prime}$)$^{16}$O(12.97 ${\rm MeV}, 2^-)$ with a water-Cherenkov detector in the supernova neutrino bursts

We first discuss and determine the isospin mixing of the two $2^-$ states (12.53 MeV and 12.97 MeV) of $^{16}$O nucleus using the inelastic electron scattering data. We then evaluate the cross section of 4.4-MeV $γ$ rays produced in the neutrino neutral-current (NC) reaction $^{16}$O($ν, ν^{\prime}$)$^{16}$O$(12.97 {\rm MeV}, 2^-$) in a water Cherenkov detector at the low energy below 100 MeV. The detection of $γ$ rays for $E_γ>5$ MeV from the NC reaction $^{16}$O($ν, ν^{\prime}$)$^{16}$O$(E_x>16\ {\rm MeV}, T=1$) with a water Cherenkov detector in the supernova neutrino bursts has been proposed and discussed by several authors previously. In this article, we discuss a new NC reaction channel from $^{16}$O(12.97 ${\rm MeV}, 2^-$) producing a 4.4-MeV $γ$ ray, the cross section of which is more robust and even larger at the low energy ($E_ν<25$ MeV) than the NC cross section from $^{16}$O$(E_x>16\ {\rm MeV}, T=1$). We also evaluate the number of such events induced by neutrinos from supernova explosion which can be observed by the Super-Kamiokande, a 32 kton water Cherenkov detector in the Earth.

astro-ph.HE↗
arXiv2020

Gamma Ray Spectra from Thermal Neutron Capture on Gadolinium-155 and Natural Gadolinium

Natural gadolinium is widely used for its excellent thermal neutron capture cross section, because of its two major isotopes: $^{\rm 155}$Gd and $^{\rm 157}$Gd. We measured the $γ$-ray spectra produced from the thermal neutron capture on targets comprising a natural gadolinium film and enriched $^{\rm 155}$Gd (in Gd$_{2}$O$_{3}$ powder) in the energy range from 0.11 MeV to 8.0 MeV, using the ANNRI germanium spectrometer at MLF, J-PARC. The freshly analysed data of the $^{\rm 155}$Gd(n, $γ$) reaction are used to improve our previously developed model (ANNRI-Gd model) for the $^{\rm 157}$Gd(n, $γ$) reaction, and its performance confirmed with the independent data from the $^{\rm nat}$Gd(n, $γ$) reaction. This article completes the development of an efficient Monte Carlo model required to simulate and analyse particle interactions involving the thermal neutron captures on gadolinium in any relevant future experiments.

nucl-ex↗
arXiv2019

Charged-current scattering off $^{16}$O nucleus as a detection channel for supernova neutrinos

Event spectra of the neutrino-$^{16}$O charged-current reactions in Super-Kamiokande are evaluated for a future supernova neutrino burst. Since these channels are expected to be useful for diagnosing a neutrino spectrum with high average energy, the evaluations are performed not only for an ordinary supernova neutrino model but also for a model of neutrino emission from a black-hole-forming collapse. Using shell model results, whose excitation energies are consistent with the experimental data, the cross sections of the $^{16}$O($ν_e, e^-$)X and $^{16}$O($\barν_e, e^+$)X reactions for each nuclear state with a different excitation energy are employed in this study. It is found that, owing to the components of the reaction with higher excitation energy, the event spectrum becomes 4-7 MeV softer than that in the case without considering the excitation energies. In addition, a simplified approach to evaluate the event spectra is proposed for convenience and its validity is examined.

astro-ph.HE↗
arXiv2018

Gamma Ray Spectrum from Thermal Neutron Capture on Gadolinium-157

We have measured the $γ$-ray energy spectrum from the thermal neutron capture, ${}^{157}$Gd$(n,γ){}^{158}$Gd, on an enriched $^{157}$Gd target (Gd$_{2}$O$_{3}$) in the energy range from 0.11 MeV up to about 8 MeV. The target was placed inside the germanium spectrometer of the ANNRI detector at J-PARC and exposed to a neutron beam from the Japan Spallation Neutron Source (JSNS). Radioactive sources ($^{60}$Co, $^{137}$Cs, and $^{152}$Eu) and the reaction $^{35}$Cl($n$,$γ$) were used to determine the spectrometer's detection efficiency for $γ$ rays at energies from 0.3 to 8.5 MeV. Using a Geant4-based Monte Carlo simulation of the detector and based on our data, we have developed a model to describe the $γ$-ray spectrum from the thermal ${}^{157}$Gd($n$,$γ$) reaction. While we include the strength information of 15 prominent peaks above 5 MeV and associated peaks below 1.6 MeV from our data directly into the model, we rely on the theoretical inputs of nuclear level density and the photon strength function of ${}^{158}$Gd to describe the continuum $γ$-ray spectrum from the ${}^{157}$Gd($n$,$γ$) reaction. Our model combines these two components. The results of the comparison between the observed $γ$-ray spectra from the reaction and the model are reported in detail.

nucl-ex↗
arXiv2015

Improving the accuracy of neutrino energy reconstruction in charged-current quasielastic scattering off nuclear targets

We report the results of a theoretical study of quasielastic electron and neutrino interactions with carbon. Our approach takes into account the effects of final-state interactions between the struck nucleon and the residual nucleus, neglected in the impulse approximation, through a generalization of the spectral function formalism. The calculated electron-scattering cross sections turn out to be in very good agreement with the available data over a broad kinematical region. The impact of nuclear effects on the reconstruction of neutrino energy in charged-current quasielastic processes is also studied, and the results of our approach are compared to the predictions of the relativistic Fermi gas model, routinely employed in most Monte Carlo simulations. Finally, we discuss the limitations of the existing procedure for energy reconstruction and propose a new, improved, one. At energy ~600 MeV, we observe a sizable difference between neutrino and antineutrino scattering, important for the measurements of charge-parity symmetry violation. Our analysis suggests that a reliable determination of neutrino energy can only be obtained from models validated by a systematic comparison to the available electron-scattering data.

nucl-th↗
arXiv2012

Gamma-ray production in neutral-current neutrino-oxygen interactions at energies above 200 MeV

We report the results of a calculation of the neutrino- and antineutrino-induced gamma-ray production cross section for oxygen target. Our analysis is focused on the kinematical region of neutrino energy larger than ~200MeV, in which single-nucleon knockout is known to be the dominant reaction mechanism. The numerical results have been obtained using a realistic model of the target spectral function, extensively tested against electron-nucleus scattering data. We find that at neutrino energy 600 MeV the fraction of neutral-current interactions leading to emission of gamma-rays of energy larger than 6 MeV is ~41%, and that the contribution of the p_{3/2} state is overwhelming.

nucl-th↗
arXiv2012

Analysis of gamma-ray production in neutral-current neutrino-oxygen interactions at energies above 200 MeV

It has long been recognized that observation of gamma rays originating from nuclear deexcitation can be exploited to identify neutral-current neutrino-nucleus interactions in water-Cherenkov detectors. We report the results of a calculation of the neutrino- and antineutrino-induced gamma-ray production cross section for oxygen target. Our analysis is focused on the kinematical region of neutrino energy larger than ~200 MeV, in which single-nucleon knockout is known to be the dominant reaction mechanism. The numerical results have been obtained using for the first time a realistic model of the target spectral function, extensively tested against electron-nucleus scattering data. We find that at neutrino energy 600 MeV the fraction of neutral-current interactions leading to emission of gamma-rays of energy larger than 6 MeV is ~41%, and that the contribution of the p_3/2 state is overwhelming.

nucl-th↗
arXiv2007

Inclusive electron spectrum in the region of pion production in electron-nucleus scattering and the effect of the quasi-elastic interaction

We have carried out a calculation of the inclusive electron scattering cross section off oxygen in the kinematical region corresponding to beam energies between 700 and 1200 MeV, where quasielastic scattering and single pion production are the dominant reaction mechanisms. The formalism developed and successfully applied to describe quasielastic scattering has been extended to include both delta production and non-resonant pion production. The results are in fairly good agreement with experimental data over the whole range of energy transfer, including the dip region between the quasielastic peak and the first resonance.

hep-ph↗
arXiv2005

Electron- and neutrino-nucleus scattering in the impulse approximation regime

A quantitative understanding of the weak nuclear response is a prerequisite for the analyses of neutrino experiments such as K2K and MiniBOONE, which measure energy and angle of the muons produced in neutrino-nucleus interactions in the energy range $0.5-3$ GeV and reconstruct the incident neutrino energy to determine neutrino oscillations. In this paper we discuss theoretical calculations of electron- and neutrino-nucleus scattering, carried out within the impulse approximation scheme using realistic nuclear spectral functions.Comparison between electron scattering data and the calculated inclusive cross section off oxygen, at beam energies ranging between 700 and 1200 MeV, show that the Fermi gas model, widely used in the analysis of neutrino oscillation experiments,fails to provide a satisfactory description of the measured cross sections,and inclusion of nuclear dynamics is needed.

hep-ph↗
arXiv2004

Comparison of electron-nucleus quasi-elastic cross sections using spectral functions with (e,e') data from 0.5 GeV to 1.5 GeV and effects on neutrino quasi-elastic cross sections

We carry out a relativistic calculation of the cross sections of electron-16O and -12C quasi-elastic scattering and quasi-free Delta production and compare with the (e,e') data systematically in the wide energy range of 0.5 - 1.5 GeV. Using the same formalism, we examine the mu-neutrino quasi-elastic scattering from 16O. The model incorporating the nuclear correlation effects agrees better with the electron-nucleus scattering data than a uniform Fermi-Gas model. In the neutrino quasi-elastic scattering, the nuclear correlation has an appreciable effect on the cross section of high-energy scattered leptons, and it may have an important consequence in the neutrino oscillation measurements aiming at a few % precision.

hep-ph↗
arXiv2003

Development of a multi-pixel photon sensor with single-photon sensitivity

A multi-pixel photon sensor with single-photon sensitivity has been developed, based on a technology of a hybrid photo-detector (HPD) consisting of a photocathode and a multi-pixel avalanche diode (MP-AD). The developed HPD has a proximity focused structure, where a photocathode and an MP-AD are facing each other with a small gap of 2.5 mm. The MP-AD, which has an effective area of 16x16 mm2 composed of 8x8 pixels, has been specially designed for the HPD. The gain of the HPD reaches 5x10^4, sufficiently high to detect single photons with a timing resolution better than 100 ps. Number of photoelectrons up to four can be clearly identified in a pulse-height spectrum as distinct peaks, thanks to the low noise characteristics of the HPD. It is also demonstrated that the HPD can be operated with good performance in a magnetic field as high as 1.5 T

physics.ins-det↗
arXiv2003

Neutrino Production of Resonances

We take a fresh look at the analysis of resonance production by neutrinos. We consider three resonances $P_{33}, P_{11}$ and $S_{11}$ with a detailed discussion of their form factors. The article presents results for free proton and neutron targets and discusses the corrections which appear on nuclear targets. The Pauli suppression factor is derived in the Fermi gas model and shown to apply to resonance production. The importance of the various resonances is demonstrated with numerical calculations. The $Δ$-resonance is described by two formfactors and its differential cross sections are compared with experimental data. The article is self-contained and could be helpful to readers who wish to reproduce and use these cross sections.

hep-ph↗
arXiv2001

Superbunch Hadron Colliders

A novel concept of a high luminosity hadron collider is proposed. This would be a typical application of an induction synchrotron being newly developed. Extremely long bunches, referred to as superbunches, are generated by a multi- bunch stacking method employing barrier buckets at the injection into the collider, and are accelerated to the collider energy with an step-voltage induced in the induction gaps. Superbunches intersect with each other, yielding a luminosity of more than $10^{35} /cm^2/sec$. A combination of vertical crossing and horizontal crossing can be used in order to avoid any significant beam-beam tune shift.

hep-ex↗