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Possible strategies of the development of low-energy nuclear physics in Russian Federation on the basis of the DERICA (Dubna Electron–Rare Isotope Collider fAcility ) project is examined. DERICA is a multiuser multipurpose facility for the production and study of radioactive isotopes (RI). In the research program of DERICA, emphasis is placed on studying RI in collector rings, but a stage-by-stage implementation of the program of DERICA would make it possible to address a wide range of fundamental problems at each stage of its development at the cutting-edge level. The ambitious goal of creating an electron–radioactive ion collider for studying basic properties of RI in electron–ion scattering is proposed for the final stage of development of DERICA.

Quasi-elastic, multi-nucleon transfer reactions induced by the radioactive-ion beams with energy 4–6 MeV/u allow one to produce moderately excited neutron-rich nuclei with atomic numbers $$95

The one-neutron transfer 2H(9Li, p)10Li reaction has been investigated at 29 A MeV incident energy at the ACCULINNA-2 facility (Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research). The setup has been used in order to detect the recoil protons at backward angles in coincidences with the outgoing 9Li and neutrons from the 10Li decay at forward angles. This setup allows to study the 10Li emitted in the crucial region at forward angles in the center of mass. The preliminary results in the part of the analysis of double proton–9Li coincidence are reported.

Investigation of the 7H-system in the experiment conducted at the fragment separator ACCULINNA-2 in the 8He(2H,3He)7H reaction requires to detect the recoil 3He ions with energy down to 6 MeV. For this purpose two $$\Delta E{\text{—}}E$$ particle telescopes are used, with each telescope having in front a thin (20-μm) Si strip detector ($$\Delta E{\text{—}}SSD$$). The maps of thickness heterogeneity of the thin detectors were determined by measuring the energy losses of the 226Ra α-particles. The adopted thickness normalization method provides a good identification of the 3He nuclei being recorded in the presence of a high 4He background. Two approaches were used for calculating the energy losses of the identified 3He and 4He reaction ejectiles and reconstructing their energy values available at the exit from the deuterium target. The developed techniques were applied for the 7H missing-mass reconstruction.

The start of operation of a new separator ACCULINNA-2 makes an important upgrade for the Radioactive-Ion Beam (RIB) research done at the Flerov Laboratory of Nuclear Reactions (FLNR, JINR). Test results indicate that the separator meets the project specifications. Intensities obtained for the 6,8He, 9,11Li, 12Be RIBs are 15 times higher in comparison with the results achieved at the old separator ACCULINNA. An overview of the design, construction and commissioning studies of the ACCULINNA-2 separator is presented. The separator will be equipped with some key facilities: a cryogenic tritium target, zero degree spectrometer following the physical target bombarded by the RIBs, and with a neutron detector array, and the Time Projection Chamber (TPC). This opens a wide range of experimental possibilities. Overview is presented on the two first experiments devoted to the study of d + 6He elastic scattering and search for a 7H low-lying resonance state populated in the 2H(8He,3He)7H reaction.

The results of uranium ion beam dynamics simulation in front-end and superconducting sections of the accelerator-driver LINAC-100 for the new rare isotope facility DERICA (JINR, Dubna) are presented. The optimum parameters are chosen for the buncher accelerator with radiofrequency quadrupole focusing (RFQ) for uranium ion beam acceleration from the ion source up to the energy of 570 keV/nucleon. LINAC-100 modular superconducting part layout for uranium beam acceleration from 3 to 100 MeV/nucleon is obtained. The energies for the stripper section installation are chosen.

A new readout system for strip semiconductor detectors has been developed based on a dedicated IDE1140 chip. The system consists of 64 spectrometric channels that provide readout of signals from detector strips. The source of the trigger signal can be either an external signal or a detector that measures the passage of an ionizing particle through the strips. The amplitude of the signal from this detector can also be used for particle spectrometry. The control and signal-readout unit for the IDE1140 chip has been designed on an EP3C16Q240 field-programmable gate array and is used for processing, storage, and transfer of acquired data. The main characteristics of the system are presented: the integral nonlinearity is

Characteristics of a new separator of radioactive ion beams (RIBs) are described. It was recently commissioned at the Flerov Laboratory of Nuclear Reactions (FLNR JINR) and is in operation at the primary beam line of the U-400M heavy ion cyclotron providing RIBs in energy range of 10–50 MeV/nucleon. Preliminary results obtained in the first experiments performed with this separator in 2018 are presented. A medium-term program of scientific research is discussed.

Three-body continuum p-p-α for the charge exchange reaction 1H(6Li,6Be)n is studied in detail. The data are obtained with a high volume of statistics (approximately 4.7 million events), making it possible to analyze three-particle correlations. Detailed information about the structure of 6Ве and the reaction is obtained as a result.

Mass measurements of the $^{69}$As, $^{70,71}$Se and $^{71}$Br isotopes, produced via fragmentation of a $^{124}$Xe primary beam at the FRS at GSI, have been performed with the multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) of the FRS Ion Catcher with an unprecedented mass resolving power of almost 1,000,000. For the $^{69}$As isotope, this is the first direct mass measurement. A mass uncertainty of 22 keV was achieved with only 10 events. For the $^{70}$Se isotope, a mass uncertainty of 2.6 keV was obtained, corresponding to a relative accuracy of $\delta$m/m = 4.0$\times 10^{-8}$, with less than 500 events. The masses of the $^{71}$Se and $^{71}$Br isotopes were measured with an uncertainty of 23 and 16 keV, respectively. Our results for the $^{70,71}$Se and $^{71}$Br isotopes agree with the 2016 Atomic Mass Evaluation, and our result for the $^{69}$As isotope resolves the discrepancy between previous indirect measurements. We measured also the mass of $^{14}$N$^{15}$N$^{40}$Ar (A=69) with a relative accuracy of $\delta$m/m = 1.7$\times 10^{-8}$, the highest yet achieved with a MR-TOF-MS. Our results show that the measured restrengthening of the proton-neutron interaction ($\delta$V$_{pn}$) for odd-odd nuclei at the N=Z line above Z=29 (recently extended to Z=37) is hardly evident at N-Z=2, and not evident at N-Z=4. Nevertheless, detailed structure of $\delta$V$_{pn}$ along the N-Z=2 and N-Z=4 lines, confirmed by our mass measurements, may provide a hint regarding the ongoing $\approx$500 keV discrepancy in the mass value of the $^{70}$Br isotope, which prevents including it in the world average of ${Ft}$-value for superallowed 0$^+\rightarrow$ 0$^+$ $\beta$ decays. The reported work sets the stage for mass measurements with the FRS Ion Catcher of nuclei at and beyond the N=Z line in the same region of the nuclear chart, including the $^{70}$Br isotope., Comment: 11 pages, 4 figures, accepted for publication at Physical Review C

A neutron spectrometer based on stilbene crystals has been developed by the Flerov Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research (Dubna, Russia). The timing resolution is determined as a function of the signal amplitude (σT = 0.18 ns at an amplitude of 1 MeV in the electron equivalent). The measured energy resolution of the detecting modules for γ rays is σE/E = 4.5% at E = 1 MeV. The quality of the n–γ discrimination is investigated. It is shown that reliable discrimination is possible, beginning with a deposited energy of 100 keV in the electron equivalent, which corresponds to the kinetic energy of recoil protons of ∼700 keV. The neutron spectrometer helps to significantly expand the experimental capabilities and to carry out correlation experiments with radioactive beams on the ACCULINNA-2 fragment separator at a new level of quality.

Physicochemical analysis methods (metallography, X-ray diffraction, differential thermal analysis, and electron microprobe analysis) are used to first study the ZrCo–ZrNi alloys in the temperature range that includes their melting and crystallization. The phase diagram of the system is constructed. The phases based on ZrCo (crystal structure of CsCl type, maximum nickel solubility about 46 at.%) and ZrNi (crystal structure of CrB type, cobalt solubility about 2 at.%) coexist in a range from room to subsolidus temperatures. The phase diagram is of peritectic type with peritectic point coordinates 1240 ± 12°C and ~48 at.% Ni.

The H7 system was populated in the H2(He8,He3)H7 reaction with a 26 AMeV He8 beam. The H7 missing mass energy spectrum, the H3 energy and angular distributions in the H7 decay frame were reconstructed. The H7 missing mass spectrum shows a peak, which can be interpreted either as unresolved 5/2+ and 3/2+ doublet or one of these states at 6.5(5) MeV. The data also provide indications of the 1/2+ ground state of H7 located at 1.8(5) MeV with quite a low population cross section of ∼25 μb/sr within angular range θc.m.≃(17°-27°).

A position-sensitive module for detecting ionizing radiation based on semiconductor strip detectors and a multichannel spectrometric route has been developed and implemented. The dynamic range of the detected charge generated by an ionizing particle in the detector is 5–250 fC. The position-sensitive module is a structurally complete device with the functions of amplifying the spectrometric signal, digitizing, buffering, preprocessing, and transmitting data to a computer.

The ^{7}H system was populated in the ^{2}H(^{8}He,^{3}He)^{7}H reaction with a 26 AMeV ^{8}He beam. The ^{7}H missing mass energy spectrum, the ^{3}H energy and angular distributions in the ^{7}H decay frame were reconstructed. The ^{7}H missing mass spectrum shows a peak, which can be interpreted either as unresolved 5/2^{+} and 3/2^{+} doublet or one of these states at 6.5(5) MeV. The data also provide indications of the 1/2^{+} ground state of ^{7}H located at 1.8(5) MeV with quite a low population cross section of ∼25 μb/sr within angular range θ_{c.m.}≃(17°-27°).

The most remote isotope from the proton dripline (by 4 atomic mass units) has been observed: ^{31}K. It is unbound with respect to three-proton (3p) emission, and its decays have been detected in flight by measuring the trajectories of all decay products using microstrip detectors. The 3p emission processes have been studied by the means of angular correlations of ^{28}S+3p and the respective decay vertices. The energies of the previously unknown ground and excited states of ^{31}K have been determined. This provides its 3p separation energy value S_{3p} of -4.6(2) MeV. Upper half-life limits of 10 ps of the observed ^{31}K states have been derived from distributions of the measured decay vertices.

The features of methods for constructing recrystallization curves of the second and third kind and the dependence “average grain size (area) - strain intensity – temperature” are given. For alloys of various structural classes VZH159 and 14Cr17Ni2 using the above methods, a recrystallization curve and the recrystallization dependence for a temperature of 1100℃ are constructed. The advantages and disadvantages of the above methods are considered.

Proceedings of the 10th International Particle Accelerator Conference The 10th International Particle Accelerator Conference, IPAC2019, Melbourne, Australia, 19 May 2019 - 24 May 2019; Geneva : JACoW Publishing/CERN 3453-3455 (2019). doi:10.18429/JACOW-IPAC2019-THPMP005, For heavy-ion accelerator facilities charge stripping is a key Technology: the stripping charge state, its efficiency to produce ions in the required charge state, and the beam quality after stripping substantially determine the entire accelerator performance. Modern heavy ion accelerator facilities such as the future Facility for Antiproton and Ion Research (FAIR) at GSI provide for high intensity heavy ion beams beyond 200 MeV/u. Heavy ion stripping at a lower energy enables more efficient acceleration up to the final beam energy, compared to acceleration of ions with a low charge state. Due to the high power deposited by the heavy ions in the stripping media and radiation damages if a solid target is used, self-recovering stripper media must be applied. General implementation options for different stripper target media are discussed in this paper, as well as general considerations to optimize the Linac layout through the appropriate choice of stripping medium and stripping energy. The driver Linac for the Dubna Electron-Radioactive Isotope Collider fAcility (DERICA) project, recently initiated by JINR, is foreseen to provide for 100 MeV/u Uranium beam in continuous wave mode. First layout scenarios of a one-step and a two-step DERICA-stripper approach will be also presented., Published by JACoW Publishing/CERN, Geneva

The proton-unbound argon and chlorine isotopes have been studied by measuring trajectories of their decay-in-flight products by using a tracking technique with micro-strip detectors. The proton ($1p$) and two-proton ($2p$) emission processes have been detected in the measured angular correlations "heavy-fragment"+$p$ and "heavy-fragment"+$p$+$p$, respectively. The ground states of the previously unknown isotopes $^{30}$Cl and $^{28}$Cl have been observed for the first time, providing the $1p$-separation energies $S_p$ of $-0.48(2)$ and $-1.60(8)$ MeV, respectively. The relevant systematics of $1p$ and $2p$ separations energies have been studied theoretically in the core+$p$ and core+$p$+$p$ cluster models. The first-time observed excited states of $^{31}$Ar allow to infer the $2p$-separation energy $S_{2p}$ of 6(34) keV for its ground state. The first-time observed state in $^{29}$Ar with $S_{2p} = -5.50(18)$ MeV can be identified either as a ground or an excited state according to different systematics., 13 pages, 14 figures. Name changed, some affiliations changed and figures corrections added

Implementing the Dubna Radioactive Ion Beams project (DRIBs) a new, efficient fragment separator ACCULINNA-2 was installed recently at the primary beam line of the U-400M cyclotron in the Flerov Laboratory of Nuclear Reactions, JINR. Since 2017, radioactive beams have been obtained from this facility. The motivation for the new RIB complex, together with an overview of the RIB research conducted in Dubna and its correlation with the worldwide RIB activities, are given in this paper. The status of the ACCULINNA-2 setup, the nearest prospects for completing its equipment, and the planned first-stage experiments are presented.

This work was supported in part by the Helmholtz International Center for FAIR (HIC for FAIR), the Helmholtz Association (grant IK-RU-002), the Russian Ministry of Education and Science (grant No. NSh- 932.2014.2), the Russian Science Foundation (grant No. 17-12-01367), the Polish National Science Center (Contract No. UMO-2011/01/B/ST2/01943), the Polish Ministry of Science and Higher Education (Grant No. 0079/DIA/2014/43,Grant Diamentowy), the Helmholtz- CAS Joint Research Group (grant HCJRG-108), the FPA2009-08848 contract (MICINN, Spain), the Justus- Liebig-Universit¨at Giesen (JLU) and GSI under the JLUGSI strategic Helmholtz partnership agreement. This article is a part of PhD thesis of X.-D. Xu. The authors acknowledge the help of D. Kostyleva in the preparation of the manuscript.

The constitution of Co–Zr alloys in the Zr2Co–Zr region is studied by physicochemical analyses (metallography, X-ray diffraction, differential thermal analysis). It is shown that the Zr3Co phase exists in the system, though the literature data on its existence and formation are contradictory. It forms in solid state at 981°C via peritectoid reaction + ↔ , and its homogeneity range at 900°C is no larger than 1 at.%. The eutectic point L ↔ + is found in the alloy with ~22 at.% Co. The microhardness of the Zr2Co and Zr3Co phases is determined.

Prospects of experimental studies of argon and chlorine isotopes located far beyond the proton dripline are studied by using systematics and cluster models. The deviations from the widespread systematics observed in $^{28,29}$Cl and $^{29,30}$Ar have been theoretically substantiated, and analogous deviations predicted for the lighter chlorine and argon isotopes. The limits of nuclear structure existence are predicted for Ar and Cl isotopic chains, with $^{26}$Ar and $^{25}$Cl found to be the lightest sufficiently long-living nuclear systems. By simultaneous measurements of protons and $\gamma$-rays following decays of such systems as well as their $\beta$-delayed emission, an interesting synergy effect may be achieved, which is demonstrated by the example of $^{30}$Cl and $^{31}$Ar ground state studies. Such synergy effect may be provided by the new EXPERT setup (EXotic Particle Emission and Radioactivity by Tracking), being operated inside the fragment separator and spectrometer facility at GSI, Darmstadt., Comment: 10 pages, 9 figures. Chapter added, language and some figures corrected

Two-proton decay of the $^{17}\mathrm{Ne}$ low-lying states populated in the $^{1}\mathrm{H}(^{18}\mathrm{Ne},d)^{17}\mathrm{Ne}$ transfer reaction is studied. The two-proton width ${\mathrm{\ensuremath{\Gamma}}}_{2p}$ of the $^{17}\mathrm{Ne}$ first excited $3/{2}^{\ensuremath{-}}$ state at ${E}^{*}=1.288$ MeV is of importance for the two-proton radioactivity theory and nuclear-astrophysics applications. A dedicated search for the two-proton emission of this state was performed leading to the new upper limit obtained for the width ratio ${\mathrm{\ensuremath{\Gamma}}}_{2p}/{\mathrm{\ensuremath{\Gamma}}}_{\ensuremath{\gamma}}l1.6(3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. An original, ``combined mass'' method is suggested and tested as capable of improving the resolution of the experiment, which is a prime significance for the study of nuclear states with extremely small particle-to-gamma width ratios ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{part}}/{\mathrm{\ensuremath{\Gamma}}}_{\ensuremath{\gamma}}$. The condition ${\mathrm{\ensuremath{\Gamma}}}_{\mathrm{part}}\ensuremath{\ll}{\mathrm{\ensuremath{\Gamma}}}_{\ensuremath{\gamma}}$ is quite common for the states of astrophysical interest, which makes the proposed approach promising in this field.

Delayed emission of protons following β decay of neutron deficient nuclei P26 and S27 was investigated at the ACCULINNA separator in the Flerov Laboratory of Nuclear Reactions at Dubna. Ions of interest, identified in flight, were implanted into the active volume of the gaseous optical time projection chamber, which allowed us to record tracks of charged particles emitted in the decay. Total branching ratios for β-delayed proton emission and for β-delayed two-proton emission were determined. In addition, energy spectra for delayed protons below 2 MeV were established. Our findings for P26 agree with results of previous experiments. In the case of S27, however, the observed probability of delayed proton emission is an order of magnitude larger than reported in literature. Two new strong proton transitions were identified representing decays of the first two excited states of P27 to the ground state of Si26. The probability ratio of γ-to-proton emission from these states is discussed.

JINR is an international scientific centre covering a broad range of activities in the nuclear, particle, theoretical physics, and biophysics. It is located in Dubna, 130 km to the north of Moscow. The JINR Laboratory Portrait can be found in a recent Nuclear Physics News article [1].

A new two-coordinate position-sensitive spectrometer for the measurements of spatial and energy distribution of ionizing particles was developed. The sensitive elements of the device are two orthogonal 64 strip semiconductor detectors whose signals are read out by two Application-Specific Integrated Circuits (ASIC) IDE1140 comprising 64 spectrometric channels each. Control, pre-processing data acquisition and transfer to a computer are carried out using FPGA circuit EP3C16Q240. The main spectrometer characteristics obtained in the measurements are: equivalent noise charge of 0.7 fC and integral nonlinearity is below 1% in the range from 5 to 160 fC.

A duplex process for the smelting of vanadium-bearing hot metal in oxygen converters is considered. Globally, this is one of the most efficient approaches to steel smelting. A wide range of high-quality steel may be produced, as well as vanadium slag for conversion to vanadium pentoxide and vanadium alloys.

New data on the cross sections of reactions that proceed during the interaction of 6He and 197Au nuclei in the 6He energy range of 40 to 120 MeV are reported. The experiments were performed using the secondary beam of the ACCULINNA separator at the Flerov Laboratory of Nuclear Reactions (FLNR), JINR. Reaction products are identified by means of activation method to measure the gamma activity of a thin-foil target assembly. Excitation functions for 6He fusion reactions with subsequent emission of up to 10 neutrons from the compound nucleus are measured. Cross sections for reactions with emission of charged particles and nucleon transfer were also measured. The experimental cross sections for the (6He, xn) reactions that proceed via the formation of a compound nucleus agree in general with calculations using models that involve the statistical approach. It is shown that the complete fusion reaction cross section drops slightly up to an energy of 114 MeV. The experimental excitation functions for the reactions resulting in the formation of mercury and gold isotopes indicate that the main contribution to their formation comes from direct processes, while the evaporation reactions (6He, pxn) and (6He, αxn) are of minor importance.

The spectrum of low-lying states in the 10He nucleus is investigated for the two-neutron transfer reaction 3H(8He, p)10He. The secondary beam of 8He nuclei with the energy 21.5 MeV/nucleon and a cryogenic tritium target are used in the experiment. The 10He ground state is observed in the missing mass spectrum at the energy of 2.1 MeV (Γ ∼ 2 MeV) above the decay threshold. Analysis of the angular correlations of the 10He decay products yields the spin and parity of two excited 10He states, J π = 1− in the energy range from 4 to 6 MeV and J π = 2+ at energies above 6 MeV.

The physics program at the super-conducting fragment separator (Super-FRS) at FAIR, being operated in a multiple-stage, high-resolution spectrometer mode, is discussed. The Super-FRS will produce, separate and transport radioactive beams at high energies up to 1.5 AGeV, and it can be also used as a stand-alone experimental device together with ancillary detectors. Various combinations of the magnetic sections of the Super-FRS can be operated in dispersive, achromatic or dispersion-matched spectrometer ion-optical modes, which allow measurements of momentum distributions of secondary-reaction products with high resolution and precision. A number of unique experiments in atomic, nuclear and hadron physics are suggested with the Super-FRS as a stand-alone device, in particular searches for new isotopes, studies of hyper-nuclei, delta-resonances in exotic nuclei and spectroscopy of atoms characterized by bound mesons. Rare decay modes like multiple-proton or neutron emission and the nuclear tensor force observed in high momentum regime can be also addressed. The in-flight radioactivity measurements as well as fusion, transfer and deep-inelastic reaction mechanisms with the slowed-down and energy-bunched fragment beams are proposed for the high-resolution and energy buncher modes at the Super-FRS. (C) 2016 Elsevier B.V. All rights reserved.

The ACCULINNA-2 separator is intended to provide beams of exotic nuclei with Z = 1−30, energies of 10–50 MeV/amu, and intensities that allow one to study excitation spectra and decay dynamics of neutron- and proton-drip nuclei. Examples from studies of the 10He and 6Be nuclei are presented.

The VMEbased data acquisition system designed for physics experiments involving measure� ments of several hundreds of parameters is described. The equipment has been tested in the experiments with the 6 He, 8 He, 18 Ne, and 27 S beams at the ACCULINNA fragment separator (http://aculina.jinr.ru/) in the energy range of 20-35 MeV/nucleon. The system is composed of the RIO�3 processor module, which is used to read the VME bus, communicate with the CAMAC and FASTBUS crates, and transmit data to the per� sonal computer; the TRIVA�5 master trigger module; st andard analogtodigital, chargetodigital, and timetodigital converters from CAEN (V785, V792 , and V775 models); and related software. This data acquisition system is faster (by a factor of 10) than a CAMACbased system and is capable of operating with new types of electronic modules, e.g., with digitizers.