1,360 research outputs found
Status of the NICA project at JINR
AbstractThe NICA (Nuclotron-based Ion Collider fAcility) project is now under active realization at the Joint Institute for Nuclear Research (JINR, Dubna). The main goal of the project is a study of hot and dense strongly interacting matter in heavy ion (up to Au) collisions at the centre-of-mass energies up to 11 GeV per nucleon. Two modes of operation are foreseen, collider mode and extracted beams, with two detectors: MPD and BM@N. The both experiments are in preparation stage. An average luminosity in the collider mode is expected as 10E27 cm-2 s-1 for Au (79+). Extracted beams of various nucleus species with maximum momenta of 13 GeV/c (for protons) will be available. A study of spin physics with extracted and colliding beams of polarized deuterons and protons at the energies up to 27 GeV (for protons) is foreseen with the NICA facility. The proposed program allows one to search for possible signs of phase transitions and critical phenomena as well as to shed light on the problem of thenucleon spin structure
Ion Exchange Properties of Irradiated and Chemically Modified Clinoptilolite Regarding to Cs⁺ and Sr²⁺
The ion exchange sorption of Cs⁺ and Sr²⁺ on clinoptilolite (CL) from deposit of Armenia in initial, modified by e- and g-irradiation, decationated with a hydrochloric acid, and cation-contained forms was studied. On the basis of received data the exchange capacity Е for Sr²⁺ and Cs⁺, distribution factor Кd, sorption factor Кs were determined. It was shown that untreated CL(Ar), decationated CL(Ar)H and Cacontaining forms are characterized by a big ion exchange activity on strontium and cesium to compare with irradiated samples and the most perspective ion exchange sorbents for these ions are CL samples modified by a chemical way.Вивчена іонообмінна сорбція Cs⁺ і Sr²⁺ з їхніх солей на клиноптилоліті з родовищ Вірменії у вихідній, модифікованій е- і g-опроміненням, а також у декатіоновоній і катіонній формах. Встановлено вплив типу хімічної обробки, ступеня зерніння і температури дегідратації зразків природного клиноптилоліту Вірменії, концентрації та об'єму промивних розчинів на поглинання цих іонів. За отриманими даними визначено обмінну ємність Е, коефіцієнти розподілу Кd і сорбції Кs. Показано, що необроблений CL (Ar), декатіонований і Са-вмісний вирізняються більшою іонообмінною ємністю у порівнянні з опроміненими, і найбільш перспективними сорбентами по відношенню до Sr²⁺ та Cs⁺ є хімічно модифіковані зразки.Изучена ионообменная сорбция Cs⁺ и Sr²⁺ из их солей на клиноптилолите из месторождений Армении в исходной, модифицированной е- и g-облучением, а также в декатионированной и катионных формах. Установлено влияние типа химической обработки, степени зернения и температуры дегидратации образцов природного клиноптилолита Армении, концентрации и объема промывных растворов на поглощение этих ионов. На основании полученных данных определены обменная емкость Е, коэффициенты распределения Кd и сорбции Кs. Показано, что необработанный CL (Ar), декатионированный и Са-содержащий отличаются более высокой ионообменной емкостью по сравнению с облученными, и наиболее перспективными сорбентами по отношению к Sr²⁺ и Cs⁺ являются химически модифицированные образцы
Stability study and time resolution measurement of Straw Tube detectors
Straw tube detectors are single wire proportional counters that are widely
used as a tracking device. We have carried out RD with a straw tube
detector prototype. The motivation of this work is to study the stability of
the performance in terms of gain and energy resolution of the straw tube
detectors under high rate radiation. Two different methods are incorporated to
perform this study. The gain and energy resolution of the detector are studied
along with its variation with ambient temperature and pressure. X-ray from a
radioactive source is used to irradiate the detector and the same source is
also used to monitor the energy spectra simultaneously for calculation of gain.
Variation of the gain and energy resolution of the straw tube detector under
X-ray irradiation in Ar/CO gas mixture is discussed in this article. We
have also estimated the time resolution of the straw tube detectors that can be
best achieved with cosmic rays as trigger for the same gas mixture. The details
of the measurement process and the experimental results are presented in this
article
Measurement of the decay form factors in the OKA experiment
A precise measurement of the vector and axial-vector form factors difference
in the decay is presented.
About 95K events of are selected in
the OKA experiment. The result is .
Both errors are smaller than in the previous measurements.Comment: 9 pages, 8 figure
Measurement of the branching ratio of the decay
From the 2002 data taking with a neutral kaon beam extracted from the
CERN-SPS, the NA48/1 experiment observed 97 candidates with a background contamination of events.
From this sample, the BR() is measured to be
Observation of the rare decay K_S -> pi^0mu^+mu^-
A search for the decay K_S -> pi^0mu^+mu^- has been made by the NA48/1
Collaboration at the CERN SPS accelerator. The data were collected during 2002
with a high-intensity K_S beam. Six events were found with a background
expectation of 0.22^+0.18_-0.11 event. Using a vector matrix element and unit
form factor, the measured branching ratio is B(K_S ->
pi^0mu^+mu^-)=[2.9^+1.5_-1.2(stat)+/-0.2(syst)]x10^{-9}.Comment: 19 pages, 8 figures, 4 tables. To be published in Physics Letters
Search for Axionlike and Scalar Particles with the NA64 Experiment
We carried out a model-independent search for light scalar (s) and
pseudoscalar axionlike (a) particles that couple to two photons by using the
high-energy CERN SPS H4 electron beam. The new particles, if they exist, could
be produced through the Primakoff effect in interactions of hard bremsstrahlung
photons generated by 100 GeV electrons in the NA64 active dump with virtual
photons provided by the nuclei of the dump. The a(s) would penetrate the
downstream HCAL module, serving as shielding, and would be observed either
through their decay in the rest of the HCAL detector or
as events with large missing energy if the a(s) decays downstream of the HCAL.
This method allows for the probing the a(s) parameter space, including those
from generic axion models, inaccessible to previous experiments. No evidence of
such processes has been found from the analysis of the data corresponding to
electrons on target allowing to set new limits on the
-coupling strength for a(s) masses below 55 MeV.Comment: This publication is dedicated to the memory of our colleague Danila
Tlisov. 7 pages, 5 figures, revised version accepted for publication in Phys.
Rev. Let
Multi-layer scintillation detector for the MOON double beta decay experiment: Scintillation photon responses studied by a prototype detector MOON-1
An ensemble of multi-layer scintillators is discussed as an option of the
high-sensitivity detector Mo Observatory Of Neutrinos (MOON) for spectroscopic
measurements of neutrino-less double beta decays. A prototype detector MOON-1,
which consists of 6 layer plastic-scintillator plates, was built to study the
sensitivity of the MOON-type detector. The scintillation photon collection and
the energy resolution, which are key elements for the high-sensitivity
experiments, are found to be 1835+/-30 photo-electrons for 976 keV electrons
and sigma = 2.9+/-0.1% (dE/E = 6.8+/-0.3 % in FWHM) at the Qbb ~ 3 MeV region,
respectively. The multi-layer plastic-scintillator structure with good energy
resolution as well as good background suppression of beta-gamma rays is crucial
for the MOON-type detector to achieve the inverted hierarchy neutrino mass
sensitivity.Comment: 8 pages, 16 figures, submitted to Nucl.Instrum.Met
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