Twenty-seven spring water samples from southwestern shore of the Caspian Sea were analysed for their contents of gross alpha and beta, ²²²Rn, ²²⁶Ra and total uranium using a liquid scintillation ...counter (LSC). Other methods such as the Environmental Protection Agency (EPA) method 900 for gross alpha/beta measurement, radon emanation for ²²⁶Ra determination and laser fluorimetry for total uranium content were applied to make a comparison with the LSC technique. The levels of measured ²²²Rn and ²²⁶Ra range from 0.5 to 54 Bq l⁻¹ and from 14 to 297 mBq l⁻¹, respectively. The levels of gross alpha and beta are from 16 mBq l⁻¹ to 1.0 Bq l⁻¹ and from 22 to 630 mBq l⁻¹, respectively. The total uranium contents are from 3 to 66 mBq l⁻¹. It has been shown that the simple liquid scintillation counting technique could be applied conveniently for such studies where analysis of numerous samples is concerned.
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The
Λ
polarization, the analyzing power, and the
Λ
spin transfer coefficient of the reaction
pp
→
pK
+
Λ
were measured at beam momenta of 2.70GeV/c and 2.95GeV/c corresponding to excess energies of ...122MeV and 204MeV. While the analyzing power and the spin transfer coefficient do not change significantly with the excess energy, the
Λ
polarization varies strongly and changes its sign. As this is the first measurement of polarization observables below an excess energy of 200MeV, the change of the sign of the
Λ
polarization was not observed before. The high statistics of the data (
≈
200 k events for each momentum) enables detailed studies of the dependence of the
Λ
polarization and the analyzing power on the center-of-mass momentum of the particles. The results of the spin transfer coefficient are in qualitative agreement with the DISTO experiment. The
Λ
polarization data of 2.95GeV/c are only conform with the DISTO experiment, while both the 2.70GeV/c and 2.95GeV/c data differ strongly from all previous measurements, whether exclusive or inclusive.
The identification of charged particles based on energy losses in straw tube detectors has been simulated. The response of a new front-end chip developed for the PANDA straw tube tracker was ...implemented in the simulations and corrections for track distance to sense wire were included. Separation power for p−K, p−π and K−π pairs obtained using the time-over-threshold technique was compared with the one based on the measurement of collected charge.
The PANDA spectrometer will be built at the FAIR facility at Darmstadt (Germany) to perform accurate tests of the strong interaction through pp and pA annihilation studies. The charged particle ...tracking at PANDA will be done using both solid state and gaseous detectors. Among the latter, two straw tube detector systems will be built 1, The cylindrical, central straw tube tracker features a high spatial and momentum resolution for a wide range of particle momenta from about 8 GeV/c down to a few 100 MeV/c, together with particle identification in the momentum region below about 1 GeV/c by measuring the specific energy-loss, A new technique, based on self-supporting straw double layers with intrinsic wire tension developed for the COSY-TOF straw tracker 2, has been adopted for the PANDA trackers. The development of the readout electronics for the straw tubes is ongoing. Prototypes have been produced and used to instrument straw tube modules that have been tested with cosmic rays and proton beams. Design issues of the PANDA straw tubes, together with the results of the prototype tests are presented.
Here, we report a systematic measurement of cumulants, Cn, for net-proton, proton, and antiproton multiplicity distributions, and correlation functions, κn, for proton and antiproton multiplicity ...distributions up to the fourth order in Au+Au collisions at √sNN = 7.7, 11.5, 14.5, 19.6, 27, 39, 54.4, 62.4, and 200 GeV. The Cn and κn are presented as a function of collision energy, centrality and kinematic acceptance in rapidity, y, and transverse momentum, pT. The data were taken during the first phase of the Beam Energy Scan (BES) program (2010–2017) at the BNL Relativistic Heavy Ion Collider (RHIC) facility. The measurements are carried out at midrapidity (|y| < 0.5) and transverse momentum 0.4 < pT < 2.0GeV/c, using the STAR detector at RHIC. We observe a nonmonotonic energy dependence (√sNN = 7.7–62.4 GeV) of the net-proton C4/C2 with the significance of 3.1σ for the 0–5% central Au+Au collisions. This is consistent with the expectations of critical fluctuations in a QCD-inspired model. Thermal and transport model calculations show a monotonic variation with √sNN. For the multiparticle correlation functions, we observe significant negative values for a two-particle correlation function, κ2, of protons and antiprotons, which are mainly due to the effects of baryon number conservation. Furthermore, it is found that the four-particle correlation function, κ4, of protons plays a role in determining the energy dependence of proton C4/C1 below 19.6 GeV, which cannot be understood by the effect of baryon number conservation.
The spin transfer from vertically polarized beam protons to Λ or Σ hyperons of the associated strangeness production p→p→pK+Λ and p→p→pK0Σ+ is described with the depolarization coefficient DNN. As ...the polarization of the hyperons is determined by their weak decays, detectors, which have a large acceptance for the decay particles, are needed. In this paper a formula is derived, which describes the depolarization coefficient DNN by count rates of a 4π detector. It is shown that formulas, which are given in publications for detectors with restricted acceptance, are specific cases of this formula for a 4π detector.
Non-monotonic variation with collision energy (√sNN) of the moments of the net-baryon number distribution in heavy-ion collisions, related to the correlation length and the susceptibilities of the ...system, is suggested as a signature for the Quantum Chromodynamics (QCD) critical point. We report the first evidence of a nonmonotonic variation in kurtosis times variance of the net-proton number (proxy for net-baryon number) distribution as a function of √sNN with 3.1σ significance, for head-on (central) gold on-gold (Au+Au) collisions measured using the STAR detector at RHIC. Data in non-central Au+Au collisions and models of heavy-ion collisions without a critical point show a monotonic variation as a function of √sNN.
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