Examination of the influence of transfer channels on the barrier height distribution: Scattering of 20Ne on 58Ni, 60Ni, and 61Ni at near-barrier energies

Background: It was suggested that the shape of the barrier height distribution can be determined not only by strong reaction channels (collective excitations) but also by weak channels such as transfers and/or noncollective excitations. Purpose: The study of the barrier height distributions for the 20Ne + 58,60,61Ni systems requires information on transfer cross sections at near-barrier energies. Methods: A measurement of the cross sections for various transfer channels at a backward angle (142 degrees), at a near-barrier energy was performed. Identification of products was based on time-of-flight and E-E methods. A measurement of the angular distribution of α stripping in the 20Ne + 61Ni s…

Performance study of the fast timing Cherenkov detector based on a microchannel plate PMT

Prototype of the fast timing Cherenkov detector, applicable in high-energy collider experiments, has been developed basing on the modified Planacon XP85012 MCP-PMT and fused silica radiators. We present the reasons and description of the MCP-PMT modification, timing and amplitude characteristics of the prototype including the summary of the detector's response on particle hits at oblique angles and MCP-PMT performance at high illumination rates. peerReviewed

Neutron halos in the excited states of 12B

The differential cross sections of the 11B(d,p) 12B reaction leading to formation of the 1+ ground state and the 0.95-MeV 2+, 1.67-MeV 2−, 2.62-MeV 1−, 2.72-MeV 0+, and 3.39-MeV 3− excited states of 12B are measured at Ed = 21.5 MeV. The analysis of the data is carried out within the coupled-reaction-channels method for the direct neutron transfer and the Hauser-Feshbach formalism of the statistical compound-nucleus model. The spectroscopic factors, asymptotic normalization coefficients, and rms radii of the last neutron in all states studied are deduced. The existence of the neutron halos in the 1.67-MeV 2− and 2.62-MeV 1− states is found, consistent with the earlier published data. New in…

Investigation of the elastic and inelastic scattering of 4He from 11B in the energy range 29-50.5 MeV

We have measured the angular distributions for the elastic and inelastic scattering of 4He from 11B in the isochronous cyclotron U-150 M INP RK. The extracted α-particles beam has been accelerated to energy 29 MeV and then directed to 11B target. The experimental results were analyzed within the framework of both the optical model using different complex potential and the double folding potential obtained with different density-dependent NN interactions which give the corresponding values of the nuclear incompressibility K in the Hartree-Fock calculation of nuclear matter. peerReviewed

T=5/2 states in 9Li: Isobaric analog states of 9He

The thick target inverse kinematic method was applied to the study of isobaric analog states in the neutron-rich nucleus 9Li. For this purpose, an excitation function for 8He+p elastic scattering was measured in the center-of-momentum energy range from 1.6 to 5.8 MeV. Three T=5/2 states in 9Li (isobaric analogs of 9He) were observed. Restrictions on the spin-parity assignments are provided according to R-matrix calculations, and conclusions regarding the structure of 9He are given. peerReviewed

Smoothing of structure in the fusion and quasielastic barrier distributions for the ^{20}Ne + ^{208}Pb system

We present simultaneously measured barrier distributions for the 20Ne + 208Pb system derived from largeangle quasielastic scattering and fusion, in the latter case by means of the detection of fission fragments. Both distributions turned out to be smooth, in spectacular disagreement with the results of standard coupled-channels calculations. Namely, they do not posses the strong structure expected from coupled-channels calculations, even if apparently they take into account explicitly all relevant strong couplings. This points to the importance of weak channels, i.e., transfer reactions and scattering connected with noncollective excitations. peerReviewed

Neutron halos in excited states of 12 B

An experiment was done to search for states with a neutron halo in 12 B. The measurements were carried out at the cyclotron of the University of Jyvaskyla (Finland) using Large Scattering Chamber (LSC). The idea of the work was to search for two states with the expected neutron halo, 1¯ and 2¯. Differential cross sections with excitation of 12 B states, including abovementioned states, were observed. The preliminary calculations on halo radii by the method of asymptotic normalization coefficients for the 2¯ and 1¯ states which are in a discrete spectrum gave following values: 5.6 fm and 7.4 fm, which is much larger than the radius of the valence neutron in the ground state. But strictly the…

Spin-parity of the 13.35 MeV state and high-lying states around 20 MeV in excitation energy in 12C nucleus

A study of the 11B(3He,d)12C reaction at incident 3He energy Elab = 25 MeV has been performed at the K-130 cyclotron at the University of Jyväskylä, Finland. Differential cross sections have been measured for the 13.35 MeV state and for the states with excitation energy around 20 MeV in 12C. The data were analyzed with the DWBA method. A tentative assignment, 4−, is given for the state at 13.35 MeV in a joint study of the reaction and inelastic scattering of α-particles with the energy of 110 MeV. For the state at 20.98 MeV, the possible spin-parity 3− and the isospin T =0 are assigned for the first time. Our model description of the broad state at 21.6 MeV is consistent with the previous as…

Measuring the 14C content in liquid scintillators

We are going to perform a series of measurements where the 14C/12C ratio will be measured from several liquid scintillator samples with a dedicated setup. The setup is designed with the aim of measuring ratios smaller than 10−18. Measurements take place in two underground laboratories: in the Baksan Neutrino Observatory, Russia and in the Pyh¨asalmi mine, Finland. In Baksan the measurements started in 2015 and in Pyh¨asalmi they start in the beginning of 2015. In order to fully understand the operation of the setup and its background contributions a development of simulation packages has also been started. Low-energy neutrino detection with a liquid scintillator requires that the intrinsic …

LBNO-DEMO (WA105): a large demonstrator of the Liquid Argon double phase TPC

LBNO-DEMO (WA105) is a large demonstrator of the double phase liquid argon TPC intended to develop and test the main elements of the GLACIER-based design for the purpose of scaling it up to the 10–50 kton size needed for Long Baseline Neutrino Oscillation studies. The crucial components of the design are: ultra-high argon purity in non-evacuable tank, long drifts, very high drift voltages, large area Micro Pattern Gas Detectors, and cold preamplifiers. The active volume of the demonstrator is 6×6×6 m3 (approximately 300t). WA105 is under construction at CERN and will be exposed to charged particle beams (0.5-20 GeV/c) in the North Area in 2018. The data will provide the necessary calibratio…

Spectroscopy of transfermium nuclei: No-252(102)

An in-beam study of excited states in the transfermium nucleus 252 No has been performed using the recoil separator RITU together with the JUROSPHERE II array at the University of Jyväskylä. This is the second transfermium nucleus studied in an in-beam experiment. Levels up to spin 20 were populated and compared to levels in 254 No . An upbend is seen at a frequency of 200 keV/ħ corresponding to spin 16. We also use an improved systematics to connect the energy of the lowest 2 + state with its half-life and find that the deformation of both 2 5 2 , 2 5 4 No is slightly larger than previously assumed. peerReviewed

The Design and Sensitivity of JUNO's scintillator radiopurity pre-detector OSIRIS

The European physical journal / C 81(11), 973 (2021). doi:10.1140/epjc/s10052-021-09544-4

Intruder features in the island of inversion : The 33Mg case

The 33 Na β decay was studied online using mass separation techniques and a first description of the level structure of the neutron-rich isotope 33 Mg , with N = 21 , has been obtained. The experiment involved the measurement of β-γ, β-γ-γ, and β − n − γ coincidences as well as neutron spectra by time-of-flight technique. The first low energy level scheme for the daughter nucleus 33 Mg is given with five bound states. Spin and parity assignments are proposed according to β feedings and γ-ray multipolarities. β-strength distribution is evaluated, taking into account 1 n - and 2 n -emission channels and it is compared with the calculated GT strength distribution. In particular, the 1 p − 1 h …

Radioactivity control strategy for the JUNO detector

JUNO is a massive liquid scintillator detector with a primary scientific goal of determining the neutrino mass ordering by studying the oscillated anti-neutrino flux coming from two nuclear power plants at 53 km distance. The expected signal anti-neutrino interaction rate is only 60 counts per day, therefore a careful control of the background sources due to radioactivity is critical. In particular, natural radioactivity present in all materials and in the environment represents a serious issue that could impair the sensitivity of the experiment if appropriate countermeasures were not foreseen. In this paper we discuss the background reduction strategies undertaken by the JUNO collaboration…

Calculation of total muon flux observed by Muon Monitor experiment

An approach to calculate the flux of cosmicgenic muons detected by Muon Monitor experiment in lab LAB2400 of the Underground Laboratory in Canfranc (LSC) is described. The measuring apparatus consists of three layers of SC16 scintillation matrix detectors. The hardware function of the detector assembly was determined using computer simulation. Obtained value of the total muon ux turned out to be equal to (4.35 ± 0.2) × 10−3 m −2 s −1. peerReviewed

Omnibus experiment: CPT and CP violation with sterile neutrinos

The verification of the sterile neutrino hypothesis and, if confirmed, the determination of the relevant oscillation parameters is one of the goals of the neutrino physics in near future. We propose to search for the sterile neutrinos with a high statistics measurement utilizing the radioactive sources and oscillometric approach with large liquid scintillator detector like LENA, JUNO, or RENO-50. Our calculations indicate that such an experiment is realistic and could be performed in parallel to the main research plan for JUNO, LENA, or RENO-50. Assuming as the starting point the values of the oscillation parameters indicated by the current global fit (in 3 + 1 scenario) and requiring at le…

Mass distributions of the system 136Xe + 208Pb at lab energies around the Coulomb barrier: a candidate reactions for production neutron-rich nuclei at N=126

Reaction products from the system 136Xe+208Pb at 136Xe ions laboratory energies of 700, 870, and 1020 MeV were studied by two-body kinematics and by a catcher-foil activity analysis to explore the theoretically proposed suitability of such reaction as a means to produce neutron-rich nuclei in the neutron shell closure N=126. Cross sections for products heavier than 208Pb were measured and were found sensibly larger than new theoretical predictions. Transfers of up to 16 nucleons from Xe to Pb were observed. peerReviewed

Fast timing and trigger Cherenkov detector for collider experiments

Analysis of fast timing and trigger Cherenkov detector’s design for its use in collider experiments is presented. Several specific requirements are taken into account – necessity of the radiator’s placement as close to the beam pipe as possible along with the requirement of gapless (solid) radiator’s design. Characteristics of the Cherenkov detector’s laboratory prototype obtained using a pion beam at the CERN Proton Synchrotron are also presented, showing the possibility of obtaining sufficiently high geometrical efficiency along with good enough time resolution (50 ps sigma). peerReviewed

Fusion-fission and quasifission of superheavy systems with Z=110-116 formed in Ca 48 -induced reactions

Background: In heavy-ion-induced reactions the mechanism leading to the formation of the compound nucleus and the role of quasifission is still not clear. Purpose: Investigation of the quasifission process of superheavy composite systems with Z = 110-116 and comparison with properties of fusion-fission and quasifission of lighter composite systems. Method: Mass and energy distributions of fissionlike fragments formed in the reactions 48Ca +232 Th, 238U, 244Pu, and 248Cm at energies near the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET at the U-400 cyclotron of the FLNR JINR. Results: The most probable fragment masses as well as total kinetic ene…

JUNO sensitivity to low energy atmospheric neutrino spectra

Atmospheric neutrinos are one of the most relevant natural neutrino sources that can be exploited to infer properties about cosmic rays and neutrino oscillations. The Jiangmen Underground Neutrino Observatory (JUNO) experiment, a 20 kton liquid scintillator detector with excellent energy resolution is currently under construction in China. JUNO will be able to detect several atmospheric neutrinos per day given the large volume. A study on the JUNO detection and reconstruction capabilities of atmospheric $\nu_e$ and $\nu_\mu$ fluxes is presented in this paper. In this study, a sample of atmospheric neutrino Monte Carlo events has been generated, starting from theoretical models, and then pro…

Neutrino Flavor Sensitivity of Large Liquid Scintillator Detectors

Scintillator detectors are known for their good light yield, energy resolution, timing characteristics and pulse shape discrimination capabilities. These features make the next-generation liquid scintillation detector LENA[1] (Low Energy Neutrino Astronomy) the optimal choice for a wide range of astro-particle topics including supernova-, solar-, and geo neutrinos. In addition to the excellent calorimetric and timing properties, scintillartor detectors (LSDs) are also capable of topology reconstruction sufficient to discriminate with adequate efficiency between electron and muon neutrino induced charge current events and neutral current events in the GeV energy range. This feature makes LEN…

Geiger mode APD’s for the underground cosmic ray experiment EMMA

Towards 14C-free liquid scintillator

A series of measurements has been started where the 14C concentration is determined from several liquid scintillator samples. A dedicated setup has been designed and constructed with the aim of measuring concentrations smaller than 10−18. Measurements take place in two underground laboratories: in the Baksan Neutrino Observatory, Russia, and in the new Callio Lab in the Pyhäsalmi mine, Finland. Low-energy neutrino detection with a liquid scintillator requires that the intrinsic 14C concentration in the liquid is extremely low. In the Borexino CTF detector the concentration of 2 × 10−18 has been achieved being the lowest value ever measured. In principle, the older the oil or gas source that…

Shell effects in damped collisions of Sr-88 with Yb-176 at the Coulomb barrier energy

[Introduction] This work is a study of the influence of shell effects on the formation of binary fragments in damped collision. We have investigated binary reaction channels of the composite system with Z = 108 produced in the reaction 88 Sr + 176 Yb at an energy slightly above the Bass barrier ( E c.m. /E Bass = 1 . 03). Reaction products were detected by using the two-arm time-of-flight spectrometer CORSET at the K130 cyclotron of the Department of Physics, University of Jyv ̈ askyl ̈ a. The mass-energy distribution of primary binary fragments has been measured. For targetlike fragments heavier than 190 u, which correspond to a mass transfer as large as twenty nucleons or more, an enhance…

Underground multi-muon experiment EMMA

EMMA is a new experiment designed for cosmic-ray composition studies around the knee energy operating at the shallow depth underground in the Pyhäsalmi mine, Finland. The array has sufficient coverage and resolution to determine the multiplicity, the lateral density distribution and the arrival direction of high-energy muons on an event by event basis. Preliminary results on the muon multiplicity extracted using one detector station of the array are presented. peerReviewed

Some Evidence of the Cluster Struture Inside of 9Be

Angular distributions of protons, deuterons, tritons and alpha-particles emitted from the reactions in the 2H+9Be-system at Elab=19.5 MeV were measured with an aim to shed light on the internal cluster structure of 9Be and the study of possible cluster transfer of 5He. The analyses suggest a significant contribution of five-nucleon transfer in the reaction channel 9Be(d,4He)7Li. peerReviewed

Doubling of α-cluster states in 22 Ne

Excitation functions for 18 O + α elastic scattering were measured by a method using inverse kinematics and a thick gas target. An analysis of the data corresponding to the excitation energy regions of 11.8–13.7 MeV and 19.0–22.0 MeV in 22 Ne was carried out. A surprising splitting of 1 − , 3 − , 7 − , and 9 − α -cluster levels into doublets was found in 22 Ne . peerReviewed

Weak channels in backscattering of ^{20}Ne on ^{nat}Ni, ^{118}Sn, and ^{208}Pb

To further our understanding of the influence of weakly coupled channels on the distribution of Coulomb barrier heights, we have measured transfer cross sections for 20Ne ions backscattered from natNi, 118Sn, and 208Pb targets at near-barrier energies. The Q value spectrum in the case of 208Pb target has been determined too. The transfer channels appear to be especially important for 208Pb, whose double-closed-shell nature leads to a relatively low level density for noncollective inelastic excitations. peerReviewed

Potential for a precision measurement of solar pp neutrinos in the Serappis experiment

The European physical journal / C 82(9), 779 (2022). doi:10.1140/epjc/s10052-022-10725-y