12 research outputs found
Detector array for the H nucleus multi-neutron decay study
Setup fitting the requirements for the detailed study of the five-body decay
of the 7H nucleus obtained as a result of the proton transfer from the 8He
projectiles to the deuterium target nuclei is being built at the radioactive
beam line of ACCULINNA-2 separator in the G.N. Flerov Laboratory of Nuclear
Reactions. Described here is the assembly of 100 BC-404 plastic scintillators,
intended for neutron detection, the annular Si detector telescope for the 3He
recoils, and the detector array providing the --TOF registration
of 3H nuclei emitted at the 7H decay. Results obtained by the Monte Carlo
simulations made for the energy values and flight passes of all these particles
are given together with the luminosity expected for the discussed experiments
Study of Proton and Deuteron Pickup Reactions 2H(10Be,3He)9Li an 2H(10Be,4He)8Li with 44 A MeV 10Be Radioactive Beam at ACCULINNA-2 Fragment Separator
The proton and deuteron pickup reactions 2H(10Be,3He)9Li and\\
2H(10Be,4He)8Li radioactive beam produced by the new fragment separator
ACCULINNA-2 at FLNR, JINR\@. These measurements were initially motivated as
test reactions intended for the elucidation of results obtained in the study of
the extremely neutron-rich 7H and 6H systems created in the 2H(10Be,3He)9Li and
2H(10Be,4He)8Li reactions using the same setup. In the 2H(10Be,3He)9Li reaction
the 9Li ground-state () and its first excited state (2.69~MeV, )
were identified in the low-energy region of its excitation spectrum. The
differential cross sections for the 9Li g.~s.) population were extracted at
forward center-of-mass angles () and compared with the FRESCO
calculations. Spectroscopic factor of , derived by a model for the
10Be9Li(g.s.) clustering was found in accord with the experimental
data. The energy spectrum of 8Li populated in the 2H(10Be,4He)8Li reaction
shows the strong peak which corresponds to excitation of the second excited
state of 8Li (2.25 MeV, ). The fact that the ground and the first excited
states of 8Li were not observed is fully consistent with Shell-Model
calculations carried out for the 10Be g.\,s. and 8Li level structure applying
momentum selection rules
The H states studied in the reaction and evidence of extremely correlated character of the H ground state
The extremely neutron-rich system H was studied in the direct
H transfer reaction with a 26
MeV secondary He beam. The measured missing mass spectrum shows a
resonant state in H at MeV relative to the H+ threshold.
The population cross section of the presumably -wave states in the energy
range from 4 to 8 MeV is
b/sr in the angular range . The
obtained missing mass spectrum is free of the H events below 3.5 MeV
( b/sr in the same angular
range). The steep rise of the H missing mass spectrum at 3 MeV allows to
show that MeV is the lower limit for the possible resonant state
energy in H tolerated by our data. According to paring energy estimates,
such a MeV resonance is a realistic candidate for the H ground
state (g.s.). The obtained results confirm that the decay mechanism of the
H g.s.\ (located at 2.2 MeV above the H+ threshold) is the
``true'' (or simultaneous) emission. The resonance energy profiles and the
momentum distributions of the sequential H \,\rightarrow \,
^5H(g.s.)+n\, \rightarrow \, ^3H+ decay fragments were analyzed by the
theoretically-updated direct four-body-decay and sequential-emission
mechanisms. The measured momentum distributions of the H fragments in the
H rest frame indicate very strong ``dineutron-type'' correlations in the
H ground state decay.Comment: 9 pages, 11 figure
Mass measurements of As, Se and Br nuclei and their implication on the proton-neutron interaction strength towards the N=Z line
Mass measurements of the nuclides 69As, 70,71Se, and 71Br, produced via fragmentation of a 124Xe primary beam at the Fragment Separator (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 1000000. Such high resolving power is the only way to achieve accurate results and resolve overlapping peaks of short-lived exotic nuclei, whose total number of accumulated events is always limited. For the nuclide 69As, this is the first direct mass measurement. A mass uncertainty of 22 keV was achieved with only ten events. For the nuclide 70Se, a mass uncertainty of 2.6 keV was obtained, corresponding to a relative accuracy of ÎŽm/m=4.0Ă10â8, with less than 500 events. The masses of the nuclides 71Se and 71Br have been measured with an uncertainty of 23 and 16 keV, respectively. Our results for the nuclides 70,71Se and 71Br are in good agreement with the 2016 Atomic Mass Evaluation, and our result for the nuclide 69As resolves the discrepancy between the previous indirect measurements. We measured also the mass of the molecule 14N15N40Ar (A=69) with a relative accuracy of ÎŽm/m=1.7Ă10â8, the highest yet achieved with an MR-TOF-MS. Our results show that the measured restrengthening of the proton-neutron interaction (ÎŽVpn) for odd-odd nuclei along the N=Z line above Z=29 (recently extended to Z=37) is hardly evident at the NâZ=2 line, and not evident at the NâZ=4 line. Nevertheless, detailed structure of ÎŽVpn along the NâZ=2 and NâZ=4 lines, confirmed by our mass measurements, may provide a hint regarding the ongoing â500 keV discrepancy in the mass value of the nuclide 70Br, which prevents including it in the world average of Ft value for superallowed 0+â0+ÎČ 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 nuclide 70Br.peerReviewe
CONTINUOUS MONITORING OF A FIBER-OPTICAL BASEBAND TRANSMISSION PATH BASED ON INTELLECTUAL OPTICAL-SIGNAL PROCESSING FACILITIES
ON THE MICROTHEORY OF SPONTANEOUS POLARIZATION AND PHASE TRANSITIONS IN CRYSTALS OF PEROVSKITETYPE AND OF ONES WITH TETRAHEDRAL STRUCTURAL UNITS
Un bref aperçu sur la microthéorie de la ferroéléctricité en cours de développement
résume ses propriétés fondamentales et les idées de base : parmi les points fondamentaux de cette
théorie on trouvera une explication de la polarisation spontané et l'origine des transitions de phase,
pour une grande variété de cristaux. Des exemples du type perovskite (BaTiO3), du type sel de
roche (GeTe) ainsi que d'autres types tels TGS et KDP sont étudiés ; les résultats sont compatibles
qualitativement avec les expériences.A breaf outlook of the developing microtheory of ferroelectricity is presented
summarizing its main features and the basic physical ideas. In the framework of this theory an
explanation of the spontaneous polarization and phase transitions origin in a wide range of different
type of crystals is given. As examples the perovskite type BaTiO3 and rock salt type GeTe as well as
TGS and KDP type crystals are considered, the result being in a good qualitative agreement with
the experiments
Electric and photoelectric characteristics of a cadmium selenide-cadmium sulfide heterojunction
Study of the Silicon Detectors for Time-of-Flight Measurements at the Super-FRS Facility and Expert Experiments at FAIR
Study of proton and deuteron pickup reactions (d,3He), (d,4He) with 8He and 10Be radioactive beams at ACCULINNA-2 fragment separator
The extremely neutron-rich systems 7H, 6H were studied in the 2H(8He, 3He)7H and 2H(8He, 4He)6H proton and deuteron pickup reactions with a 26 AMeV secondary 8He beam produced at the new ACCULINNA-2 fragment separator. In addition, the same proton and deuteron pickup reactions were generated using the 42 AMeV 10Be beam, and the population of low-lying 9Li and 8Li states was measured in reactions 2H(10Be,3He)9Li and 2H(10Be,4He)8Li, respectively. The latter were used as reference measurements in order to check the setup calibration over the excitation energy of 7,6H and to determine the real experimental energy resolution which was compared with Monte Carlo calculations. The corresponding results obtained for the superheavy hydrogen systems 7H, 6H are presented and discussed. Typical excitation spectra of the 9Li and 8Li nuclei are also shown