Nucleus Interactions Research Articles

Production of High-Transverse-Momentum Deuterons and Tritons at an Angle of 40{{}^{circ}} in Proton–Nucleus Interactions at a Beam Energy of 50 GeV

Data on the production of positively charged particles emitted at an angle of 40{}^{circ} (in the laboratory frame) with transverse momenta of up to 2.7 GeV/c in the interaction of 50-GeV/c protons with carbon, aluminum, copper, and tungsten nuclear targets are presented. Particular attention is given to studying the production of light nuclear fragments, such as deuterons (d) and tritons (t). An analysis of data on d and t particles gives grounds to state that these fragments arise via a local mechanism of their direct knockout from nuclei. The results were obtained in the SPIN experiment at the Institute for High Energy Physics (IHEP, Protvino).

Calculation of electric field gradients for CdI2 in the gas phase using BOMD simulations

The nuclear quadrupole interaction (NQI) of quadrupolar nuclei in molecules in the gas phase has recently been quantified experimentally by the technique of Perturbed Angular Correlation (PAC) spectroscopy. Interpretation of the NQI data must rely on high-level electronic structure methods for the calculation of the electric field gradient (EFG). These calculations commonly omit contributions from anharmonicity, rovibrational coupling and (if applicable) decay-induced nuclear recoil to the molecular structure and the response of the EFG. Here we choose an alternative approach, conducting Born–Oppenheimer molecular dynamics (BOMD) simulations, and account for the effects of molecular motion on the EFG. We apply this approach to the analysis of PAC spectroscopic data recorded for gas phase CdI2 (Haas et al., 2021). With this methodology, we obtain a value of the nuclear quadrupole moment Q(111Cd, 5/2+) = 0.656(7) b.

Measurements of _{Λ}^{3}H and _{Λ}^{4}H Lifetimes and Yields in Au+Au Collisions in the High Baryon Density Region.

We report precision measurements of hypernuclei _{Λ}^{3}H and _{Λ}^{4}H lifetimes obtained from Au+Au collisions at sqrt[s_{NN}]=3.0 GeV and 7.2GeV collected by the STAR experiment at the Relativistic Heavy Ion Collider, and the first measurement of _{Λ}^{3}H and _{Λ}^{4}H midrapidity yields in Au+Au collisions at sqrt[s_{NN}]=3.0 GeV. _{Λ}^{3}H and _{Λ}^{4}H, being the two simplest bound states composed of hyperons and nucleons, are cornerstones in the field of hypernuclear physics. Their lifetimes are measured to be 221±15(stat)±19(syst) ps for _{Λ}^{3}H and 218±6(stat)±13(syst) ps for _{Λ}^{4}H. The p_{T}-integrated yields of _{Λ}^{3}H and _{Λ}^{4}H are presented in different centrality and rapidity intervals. It is observed that the shape of the rapidity distribution of _{Λ}^{4}H is different for 0%-10% and 10%-50% centrality collisions. Thermal model calculations, using the canonical ensemble for strangeness, describes the _{Λ}^{3}H yield well, while underestimating the _{Λ}^{4}H yield. Transport models, combining baryonic mean-field and coalescence (jam) or utilizing dynamical cluster formation via baryonic interactions (phqmd) for light nuclei and hypernuclei production, approximately describe the measured _{Λ}^{3}H and _{Λ}^{4}H yields. Our measurements provide means to precisely assess our understanding of the fundamental baryonic interactions with strange quarks, which can impact our understanding of more complicated systems involving hyperons, such as the interior of neutron stars or exotic hypernuclei.

Wide angle acceptance and high-speed track recognition in nuclear emulsion

Abstract A nuclear emulsion film is a three-dimensional tracking device that is widely used in cosmic-ray and high-energy physics experiments. Scanning with a wide angle acceptance is crucial for obtaining track information in emulsion films. This study presents a new method developed for wide angle acceptance and high-speed track recognition of nuclear emulsion films for neutrino–nucleus interaction measurements. The nuclear emulsion technique can be used to measure tracks of charged particles from neutrino interactions with a low momentum threshold. The detection of the particles with a wide angle acceptance is essential for obtaining detailed information on the interactions in the sub- and multi-GeV neutrino energy region. In the new method developed for a neutrino interaction measurement in J-PARC called NINJA, the angle acceptance is covered up to |tan θx(y)| < 5.0 (80% of all solid angles) with $150\, \mathrm{m^2/year}$. This method can also be used to improve the angle accuracy and recognition efficiency of the tracks.

Galactic gamma-ray and neutrino emission from interacting cosmic-ray nuclei

We present a study of the expectations for very-high-energy (VHE) to ultra-high-energy (UHE) gamma-ray and neutrino emission from interacting cosmic rays in our Galaxy as well as a comparison to the latest results for the Galactic UHE diffuse emission. We demonstrate the importance of properly accounting for both the mixed cosmic-ray composition and the gamma-ray absorption. We adopt the wounded-nucleon model of nucleus interactions and provide parameterisations of the resulting gamma-ray and neutrino production. Nucleon shielding due to clustering inside nuclei is shown to have a measurable effect on the production of gamma rays and is particularly evident close to breaks and cutoffs in mixed-composition particle spectra. The change in composition around the ‘knee’ in the cosmic ray spectrum has a noticeable impact on the diffuse neutrino and gamma-ray emission spectra. We show that current and near-future detectors can probe these differences in the key energy range from 10 TeV to 1 PeV, testing the paradigm of the universality of the cosmic ray spectrum and composition throughout the Galaxy.

Design and performance of a scintillation tracker for track matching in nuclear-emulsion-based neutrino interaction measurement

Precise measurement of neutrino–nucleus interactions with an accelerator neutrino beam is highly important for current and future neutrino oscillation experiments. To measure muon-neutrino charged-current interactions with nuclear-emulsion-based hybrid detector, muon track matching among the detectors are essential. We describe the design and performance of a newly developed scintillation tracker for the muon track matching in the neutrino–nucleus interaction measurement with nuclear emulsion detectors. The muon tracks are reconstructed using the scintillation tracker and another detector called Baby MIND, then, they are matched with the tracks in nuclear emulsion detectors.The scintillation tracker consists of four layers of horizontally and vertically aligned scintillator bars, covering an area of 1m×1m. In the layer, 24mm-wide plastic scintillator bars are specially arranged with deliberate gaps between each other. By recognizing the hit pattern of the four layers, a precise positional resolution of 2.5mm is achieved while keeping the number of readout channels as small as 256. The efficiency of the track matching is evaluated to be more than 97% for forward-going muons, and the positional and angular resolutions of the scintillation tracker are 2.5mm and 20–40mrad respectively. The results demonstrate the usefulness of the design of the scintillation tracker for the muon track matching in the nuclear-emulsion-based neutrino–nucleus interaction measurements.

Transport equations for driven many-body quantum systems

Transport equations for autonomous driven fermionic quantum systems are derived with the help of statistical assumptions, and of the Markov approximation. The statistical assumptions hold if the system consists of subsystems within which equilibration is sufficiently fast. The Markov approximation holds if the level density in each subsystem is sufficiently smooth in energy. The transport equation describes both, relaxation of occupation probability among subsytems at equal energy that leads to thermalization, and the transport of the system to higher energy caused by the driving force. The laser–nucleus interaction serves as an example for the applicability and flexibility of the approach.

Study on NaI(Tl) crystal at −35 [formula omitted]C for dark matter detection

We present the response of a NaI(Tl) crystal in terms of the light yield and pulse shape characteristics at two different temperatures: 22 °C (room temperature) and −35 °C (low temperature). The light yield is measured using 59.54keV γ-rays from a 241Am source relative to the mean charge of single photoelectrons. At the low temperature, we measure a 4.7 ± 1.3% increase in the light yield compared to that at room temperature. A significantly increased decay time is also observed at the low temperature. The responses to nuclear recoil events are measured using neutrons from a 252Cf source and compared to those to electron recoil events. The measured pulse shape discrimination (PSD) power of the NaI(Tl) crystal at the low temperature is found to be improved in the entire energy range studied because of the increased light yield and the different scintillation characteristics. We also find a 9.23 ± 0.26% increased quenching factor of α-induced events, which is the light yield ratio of α recoil to electron recoil, at the low temperature. This supports the possibility of an increased quenching factor of the nuclear recoil events that are known to have similar processes of dark matter interaction. The increased light yield and the improved PSD power of nuclear recoil events enhance the sensitivity for dark matter detection via dark matter–nuclei interactions.

A new kaonic helium measurement in gas by SIDDHARTINO at the DAΦNE collider*

Abstract The SIDDHARTINO experiment at the DAΦNE collider of INFN-LNF, the pilot run for the SIDDHARTA-2 experiment which aims to perform the measurement of kaonic deuterium transitions to the fundamental level, has successfully been concluded in July 2021. The paper reports the main results of this run, including the optimization of various components of the apparatus, among which the degrader needed to maximize the fraction of kaons stopped inside the target, through measurements of kaonic helium transitions to the 2p level. The obtained shift and width values are ε 2p = E exp − E e.m = 0.2 ± 2.5(stat) ± 2.0(syst) eV and Γ2p = 8 ± 10 eV (stat), respectively. This new measurement of the shift, in particular, represents the most precise one for a gaseous target and is expected to contribute to a better understanding of the kaon–nuclei interaction at low energy. The results obtained in this pilot run, combined with the foreseen additional veto systems and projected for the total 48 SDD arrays of the SIDDHARTA-2 final setup, represent a solid starting point for the successful measurement of the kaonic deuterium 2p → 1s transition, main goal of the experiment.

Reaction 14C(11B, 12C)13B at Elab(11B) = 45 MeV, interaction of 13B + 12C versus that of 10,11,12B + 12C

New experimental data for differential cross-sections of the 14C(11B, 12C)13B reaction obtained recently at the energy Еlab(11B) = 45 MeV for the ground states of 13B and 12C were analyzed within the coupled reaction channels (CRC) method that included the 11B + 14C elastic scattering channel as well as channels for one- and two-step transfers of nucleons in the coupling scheme. The necessary 11B + 14C Woods - Saxon (WS) optical potential parameters for the entrance reaction channel were obtained from 11B elastic scattering in the previous work, while those for 12C + 13B interaction were deduced from fitting the CRC calculations to the 14C(11B, 12C)13B reaction data. Needed spectroscopic amplitudes of transferred nucleons and clusters were calculated within the translational-invariant shell model. The data are well described by the direct transfer of a proton while contributions from two-step transfers were found to be negligible. The deduced 13B + 12C WS optical potential parameters are compared with those of the 10,11,12B + 12C nuclei interactions. The effect of isotopic differences in these interactions was observed.

Integral nucleus-nucleus cross-sections

Abstract Expressions approximating the experimental integral cross-sections for elastic and inelastic interactions of light and heavy nuclei at energies up to several GeV/nucleon are presented. The calculated cross-sections are inside the corridor of experimental errors or very close to it.

Symmetries in the Superposition Model of Extensive Air Shower Development

According to the superposition principle, an extensive air shower initiated by a nucleus with energy E and mass number A can be approximated as the superposition of A proton-initiated showers each with energy E/A. The superposition principle for interactions of atomic nuclei proposes to describe nucleus-initiated extensive air showers using simulations performed for proton showers. Single detectors and systems working in tight coincidence mainly register events initiated by particles with very low energies, which are affected by major statistical fluctuations, such as those used in high schools for education and outreach purposes. Verifying whether the superposition principle is still a good approximation in the low-energy region is important for the validity of the interpretation of such measurements. We present results of the comparison of results of the superposition model with detailed simulations of showers with the CORSIKA program from the energy of 10 GeV. While the energy dependence of the mean shower parameters satisfies the superposition principle, the higher moments do not. A modification of the superposition model based on the wounded nucleon model, reducing these discrepancies, is proposed. The semi-analytical description of showers in the modified superposition model can give the density spectrum of cosmic ray particles, which is consistent with the measurements. In this paper, we present results both consistent with the superposition model and indicating the need for its modification. This modification is proposed and tested.

Detections of inflowing gas from narrow absorption lines at parsec scales

The detection of inflows at the scale of the dusty torus and smaller is crucial for investigating the process of supermassive black hole (SMBH) accretion. However, only a few cases of inflowing gas at small scales have been reported through redshifted broad absorption lines so far. Here we report nine redshifted narrow absorption lines (NALs) of Mg+ions with inflowing speeds of 1071–1979 km s−1, which are likely along the directions close to the axes of accretion disks. The quasars showing inflowing Mg IINALs have, on average, slightly smaller Eddington ratios than the sources with outflowing Mg IINALs. The upper limits on the locations of the detected NALs are at parsec scale, that is, the distance from dusty tori to their central SMBHs. One possible origin of these infalling NALs is from dusty tori. However, these infalling NALs could also be naturally explained by chaotic cold accretion resulting from the nonlinear interaction of active galactic nucleus (AGN) jets with the interstellar medium (ISM), and these cold gaseous blobs may originally precipitate in metal-rich trailing outflows uplifted by AGN jet ejecta. The infalling NALs may therefore provide direct evidence for cold gas precipitation and accretion in AGN feedback processes, and provide direct evidence of inflowing gas along the directions close to quasar jets and at parsec scale. Regardless of whether these infalling NALs are from the dusty tori or the interaction of AGN jets with the ISM, the infalling NALs cannot provide sufficient fuel to power the quasars.

Evolution of collectivity and neutron-proton interactions

In this paper we study the correlation between the evolution of nuclear collective motion and neutron-proton interactions. We construct empirical neutron-proton interactions (denoted by ${V}_{\mathrm{NP}}$) for nuclei in the $(28<Z<50,$ $50<N<82)$, $(50<Z<82,$ $50<N<82$), and $(50<Z<82,$ $82<N<126)$ major shells. The ratios between ${V}_{\mathrm{NP}}$ and ${N}_{\mathrm{n}}{N}_{\mathrm{p}}$ (the product of valence proton number and valence neutron number) are found to be different for particle-particle, particle-hole, and hole-hole regions of the same major shell, suggesting different average strengths of neutron-proton interactions for these regions. Very interestingly, collective observables of even-even nuclei, e.g., ${2}^{+}$ and ${4}^{+}$ state energies, which follow different trajectories in the ${N}_{\mathrm{n}}{N}_{\mathrm{p}}$ scheme for particle-particle, particle-hole, and hole-hole regions, are found to form one unified and compact trajectory if those collective observables are plotted in terms of total neutron-proton interactions, ${V}_{\mathrm{NP}}$.

Parton rescattering and gluon saturation in dijet production at EIC

Large angle gluon radiations induced by multiple parton scatterings contribute to dijet production in deeply inelastic scattering off a large nucleus at the Electron-Ion Collider. Within the generalized high-twist approach to multiple parton scattering, such contributions at the leading order in perturbative QCD and large Bjorken momentum fraction $x_B$ can be expressed as a convolution of the multiple parton scattering amplitudes and the transverse momentum dependent (TMD) two-parton correlation matrix elements. We study this medium-induced dijet spectrum and its azimuthal angle correlation under the approximation of small longitudinal momentum transfer in the secondary scattering and the factorization of two-parton correlation matrix elements as a product of quark and gluon TMD parton distribution function (PDF). Using a simple model for gluon saturation based on the parametrized gluon TMD PDF, we can calculate the $x_B$ and $Q^2$ dependence of the saturation scale and parton transport coefficient $\hat q$. Contributions to dijet cross section from double scattering are power-suppressed and only become sizable for mini-jets at small transverse momentum. We find that the total dijet correlation for these mini-jets, which also includes the contribution from single scattering, is sensitive to the transverse momentum broadening in the quark TMD PDF at large $x$ and saturation in the gluon TMD PDF at small $x$ inside the nucleus. The correlation from double scattering is also found to increase with the dijet rapidity gap and have a quadratic nuclear-size dependence because of the Landau-Pomeranchuk-Migdal (LPM) interference in gluon emission induced by multiple scattering. Experimental measurements of such unique features in the dijet correlation can shed light on the LPM interference in strong interaction and gluon saturation in large nuclei.

Testing the superposition model in small CORSIKA shower simulations

The idea of superposition in the high-energy interactions of cosmic ray nuclei and the development of extensive air showers initiated by them has been known for more than half a century. It has been thoroughly and successfully tested in a number of simulations for primary energies around 1015 and above. In this work, we will investigate its applicability to lower energies. At the lowest energies, when the shower contains on average about one charged particle (or even less), deviations from the superposition model can be seen in the simulation results. Fluctuations of higher moments of the main shower parameters are systematically broader than expected. Further studies to confirm superposition in particular in the shower longitudinal profile are in progress. A correct description of the longitudinal development of the small shower, a precise description of its fluctuations on the observational level with a correct implementation of the superposition principle will enable to construct a simple and fast phenomenological algorithm generating small showers indispensable for the interpretation of measurements made using a small local shower array and determination of the flux of single, incoherent, secondary cosmic ray particles.

Pre-Equilibrium Clustering in Production of Spectator Fragments in Collisions of Relativistic Nuclei

An algorithm of pre-equilibrium clustering of spectator matter based on the construction of the minimum spanning tree (MST) is presented. The algorithm was implemented in the Abrasion-Ablation Monte Carlo for Colliders (AAMCC) model designed to study the characteristics of spectator matter in collisions of relativistic nuclei. Due to accounting for the pre-equilibrium clusters in modelling 208Pb–208Pb collisions at the LHC, the agreement of simulation results with experimental data on the average multiplicities of spectator nucleons was improved. The results of the AAMCC-MST were compared with experimental data on the interactions of 197Au nuclei in nuclear photoemulsion. Comparison of the yields of spectator nuclei calculated for 16O–16O collisions with the yields measured in interactions of 16O with light nuclei of photoemulsion made it possible to estimate the effect of MST-clustering in small nuclear systems.

Ultrafast nonadiabatic dynamics of λ-DNA upon low energy proton irradiation

Direct ionizing damage and indirect secondary electron damage play important parts in the cell death under ion beam radiation. Depending on the real-time time-dependent density functional theory, we study the physical and chemical properties of the normal (α-) and mutant DNA (λ-DNA) in the process of low energy proton irradiation. The mutation of base pair causes the change in local chemical environment of DNA molecule and further changes the charge density of trajectory, proton–DNA interaction energy, force and track for moving proton, energy deposition, and the secondary electron evolution. The layered discrete charge in the intruding direction results in a spatial insensitivity of the electrons on the base pair to the energetic ion. The abnormal energy deposition for λ-DNA is ascribed to the mutation of the charge density and the nucleus–nucleus interaction potential. A more stable bond is formed between the mutant base pairs for λ-DNA, and there exists a flow of secondary electrons on the phosphate backbone under the ion beam radiation, resulting in a subsequent indirect chemical damage. These results provide an understanding for the central role of the physical states in radiation-induced cell death and a theoretical reference to improve the success rate of ion beam radiotherapy.

تفاعل كوكني وتوزيع الشحنة النووية في نواة الكالسيوم 48

تمت دراسة عوامل التشكل الكولومية لمتعددة الاقطاب لنواة 48Ca باستخدام نموذج القشرة النووية. وقد أدخل الجهد النووي fpmb لزوج الجسيمتين للحسابات لتركيب LS. اعتمد جهد المتذبذب التوافقي Jp`tكدالة موجة للجسيم المنفرد في الفضاء Fp . وقد أضيفت الفضاءات العليا وتأثيرات القلب الخامل كتصحيح من المرتبة الاولى. تم استخدام جهد الجسيمتين الدقيق لكوكني لتفاعل الجسيمات الفعالة في الفضاء مع زوج (جسيم-فجوة) في الفضاءات المستثناة و بطاقة تهيج مقدارها 2ћω .ان اختيار تفاعل كوكني تم على اساس نجاحه في نظرية القشرة. تم مقارنة النتائج مع القيم العملية.

WASp triggers mechanosensitive actin patches to facilitate immune cell migration in dense tissues.

SummaryWhen crawling through the body, leukocytes often traverse tissues that are densely packed with extracellular matrix and other cells, and this raises the question: How do leukocytes overcome compressive mechanical loads? Here, we show that the actin cortex of leukocytes is mechanoresponsive and that this responsiveness requires neither force sensing via the nucleus nor adhesive interactions with a substrate. Upon global compression of the cell body as well as local indentation of the plasma membrane, Wiskott-Aldrich syndrome protein (WASp) assembles into dot-like structures, providing activation platforms for Arp2/3 nucleated actin patches. These patches locally push against the external load, which can be obstructing collagen fibers or other cells, and thereby create space to facilitate forward locomotion. We show in vitro and in vivo that this WASp function is rate limiting for ameboid leukocyte migration in dense but not in loose environments and is required for trafficking through diverse tissues such as skin and lymph nodes.