Van-Toan Phan, Duy-Sang Nguyen, Thi-Kiem-Thu Tran
et al.
This study systematically investigates the thermoluminescent properties of K2GdF5:Tb phosphor, with an emphasis on determining and comparing kinetic parameters relevant to radiation dosimetry. Thermoluminescence glow curves obtained after X-ray irradiation at effective photon energies of 33.3 keV, 65.2 keV, and 100 keV and after mixed neutron-gamma irradiation from a ?4?Am-Be source were analyzed using the initial rise, peak shape, and area peak methods in combination with several kinetic models, including first-order, second-order, general-order, mixed-order, and one-trap-one-recombination-center models. Reference glow curves were employed to verify the stability and reliability of the applied analysis procedures. Experimental results showed that X-ray irradiated K2GdF5:Tb exhibits a single dominant glow peak at approximately 482-484 K, with activation energies in the range of 0.60-0.77 eV. In contrast, mixed neutron-gamma irradiation leads to two partially overlapping glow peaks, characterized by lower activation energies in the range of 0.10-0.38 eV, indicating the presence of shallow and intermediate trapping components. The extracted kinetic parameters exhibited good consistency within experimental uncertainties and were associated with low figure-of-merit values, thereby confirming the reliability of the applied analysis methods. These results provide provide a deeper understanding of the distinct trapping mechanisms induced by photon and neutron interactions and demonstrate the potential of K2GdF5:Tb for radiation dosimetry applications under X-ray and mixed neutron-gamma fields.
This paper introduces a measuring system designed to determine the air density correction factor for ionization chambers open to the atmosphere. The system is intended for use in clinical and radiotherapy facilities, secondary standard dosimetry laboratories, and other settings where open-to-the-air ionization chambers are commonly utilized. While there are numerous universal and laboratory-grade instruments available for measuring relative humidity, air pressure, and ambient temperature, integrated systems that can measure these parameters and calculate and display the air density correction factor are rare, particularly in the domestic market in Serbia. This paper details the developed hardware, including specifications for the sensors used, as well as the software developed for microcontrollers and personal computers. Measurement results and simplified measurement uncertainty budgets are also presented and discussed.
The contribution of one neutron stripping cross section to the total reaction cross section has been studied for $^9$Be projectile incident on $^{169}$Tm, $^{181}$Ta, $^{187}$Re and $^{197}$Au targets around Coulomb barrier energy. The measured one neutron stripping cross sections for these systems have been compared with the coupled channel calculations. The recently developed global set of optical model potential parameters for $^9$Be projectile has been used in the present calculations. The cumulative of measured complete fusion (CF), incomplete fusion (ICF), one neutron stripping and calculated non-capture breakup (NCBU) cross sections is found to explain almost the reaction cross sections for all the targets. A very small contribution from target inelastic states and elastic breakup may contribute to the remaining part. The percentage fraction of cross section for CF, ICF, one neutron stripping, and NCBU over reaction cross section show the dominance of neutron transfer and NCBU at below barrier energies while CF and ICF processes have the major contribution at above barrier energies.
Nuclear Fermi momentum is a basic property of a nucleus where many nucleons dwell. However, in experiments only the nuclear Fermi momenta of just a few nuclei are measured using quasielastic electron scattering on the nuclear targets so far. Particularly, we still do not know experimentally the Fermi momentum of the lightest nucleon composite -- the deuteron. In this paper, we apply both gaussian distribution and Cauchy distribution to describe the quasielastic peak in the cross section of electron-nucleus scattering. The dip of the cross-section ratio at about $x_{\rm B}=1$ is explained with the nuclear Fermi momentum. By performing the least-square fits to the published CLAS data in the narrow kinematic region of quasielastic scattering, we obtain the nuclear Fermi momenta of $^{2}$H, $^{27}$Al and $^{56}$Fe, which are $116\pm 7$ MeV/c, $232\pm 27$ MeV/c, and $244\pm 28$ MeV/c respectively. The extracted nuclear Fermi momenta are compared to the simple calculations based on Fermi gas model, and the consistencies are found.
Within a transport model, we study effects of the momentum dependence of nuclear symmetry potential on pion observables in central Sn + Sn collisions at 270 MeV/nucleon. To this end, a quantity $U_{sym}^{\infty}(ρ_{0})$, i.e., the value of nuclear symmetry potential at the saturation density $ρ_{0}$ and infinitely large nucleon momentum, is used to characterise the momentum dependence of nuclear symmetry potential. It is shown that with a certain $L$ (i.e., slope of nuclear symmetry energy at $ρ_{0}$) the characteristic parameter $U_{sym}^{\infty}(ρ_{0})$ of symmetry potential affects significantly the production of $π^{-}$ and $π^{+}$ as well as their pion ratios. Moreover, through comparing the charged pion yields, pion ratios as well the spectral pion ratios of theoretical simulations for the reactions $^{108}$Sn + $^{112}$Sn and $^{132}$Sn + $^{124}$Sn with the corresponding data in S$π$RIT experiments, we find that our results favor a constraint on $U_{sym}^{\infty}(ρ_{0})$, i.e., $-160^{+18}_{-9}$~MeV, and the $L$ is also suggested within a range, i.e., $62.7<L<93.1$~MeV. In addition, it is shown that the pion observable of $^{197}$Au + $^{197}$Au collisions at 400~MeV/nucleon also supports the extracted value for $U_{sym}^{\infty}(ρ_{0})$.
In this paper, we present a straightforward analytical method for calculating the efficiencies of an ovoid shape (elliptical cylindrical) detector by using a randomly located point source. To determine the activity of an unknown radioactive source, absolute efficiency is required and we should take into account the attenuation of the gamma-ray photons by the source container and the detector housing materials. The soundness of the resultant straightforward analytical method was successfully confirmed by comparison with some published data.
In this review article we discuss the present status of direct nuclear reactions and the nuclear structure aspects one can study with them. We discuss the spectroscopic information we can assess in experiments involving transfer reactions, heavy-ion-induced knockout reactions and quasifree scattering with (p,2p), (p,pn), and (e,e'p) reactions. In particular, we focus on the proton-to-neutron asymmetry of the quenching of the spectroscopic strength.
Extensive work has been carried out on measurement of radon and thoron levels in indoor environment in last three decades. These studies are important from radiation protection point of view, if one considered the contribution of radon, thoron and their decay products to total inhalation dose. Numerous studies on radon measurement well established the behaviour of its dispersion in dwellings. But the short lives of thoron cause the difficulty to understand the distribution of thoron in dwellings. The problem becomes more complicated when thoron dispersion is studied under different inlet air flow rate. Different air flow pattern may cause different thoron level at different point in test dwellings causing uncertainty in the measurements. This work utilized the CFD simulation technique for study of indoor thoron dispersion in test dwellings under normal and turbulent flow of air. The simulation study for thoron distribution in a test room was performed for air velocities 0.10 ms-1, 0.25 ms-1, 0.50 ms-1, 1.0 ms-1, 1.5 ms-1, and 2.0 ms-1. The results show that the thoron distribution becomes uniform for the inlet velocity more than 0.5 ms-1 and appropriate to measure indoor thoron concentration. While in normal condition the measured thoron level varies depending upon the location of dosimeter. Thoron diffusion and migration length are also increased with air flow rate.
When using gamma ray spectrometry for radioactivity analysis of environmental samples (such as soil, sediment or ash of a living organism), relevant linear attenuation coefficients should be known - in order to calculate self-absorption in the sample bulk. This parameter is additionally important since the unidentified samples are normally different in composition and density from the reference ones (the latter being e. g. liquid sources, commonly used for detection efficiency calibration in radioactivity monitoring). This work aims at introducing a numerical simulation method for calculation of linear attenuation coefficients without the use of a collimator. The method is primarily based on calculations of the effective solid angles - compound parameters accounting for the emission and detection probabilities, as well as for the source-to-detector geometrical configuration. The efficiency transfer principle and average path lengths through the samples themselves are employed, too. The results obtained are compared with those from the NIST-XCOM data base; close agreement confirms the validity of the numerical simulation method approach.
The geometric-mean method is often used to estimate the spatial resolution of a position-sensitive detector probed by tracks. It calculates the resolution solely from measured track data without using a detailed tracking simulation and without considering multiple Coulomb scattering effects. Two separate linear track fits are performed on the same data, one excluding and the other including the hit from the probed detector. The geometric mean of the widths of the corresponding exclusive and inclusive residual distributions for the probed detector is then taken as a measure of the intrinsic spatial resolution of the probed detector: $σ=\sqrt{σ_{ex}\cdotσ_{in}}$. The validity of this method is examined for a range of resolutions with a stand-alone Geant4 Monte Carlo simulation that specifically takes multiple Coulomb scattering in the tracking detector materials into account. Using simulated as well as actual tracking data from a representative beam test scenario, we find that the geometric-mean method gives systematically inaccurate spatial resolution results. Good resolutions are estimated as poor and vice versa. The more the resolutions of reference detectors and probed detector differ, the larger the systematic bias. An attempt to correct this inaccuracy by statistically subtracting multiple-scattering effects from geometric-mean results leads to resolutions that are typically too optimistic by 10-50\%. This supports an earlier critique of this method based on simulation studies that did not take multiple scattering into account.
Shiori Takeuchi, Koichi Murase, Tetsufumi Hirano
et al.
We study effects of the hadronic rescattering on final observables especially for multi-strange hadrons such as $φ$, $Ξ$ and $Ω$ in high-energy heavy-ion collisions within an integrated dynamical approach. In this approach, (3+1)-dimensional ideal hydrodynamics is combined with a microscopic transport model, JAM. We simulate the collisions with or without hadronic rescatterings and compare observables between these two options so that we quantify the effects of the hadronic rescattering. We find that the mean transverse momentum and the elliptic flow parameter of multi-strange hadrons are less affected by hadronic rescattering and, as a result, the mass ordering of the $p_T$-differential elliptic flow parameter $v_2(p_T)$ is violated: At the RHIC and the LHC energies the $v_2(p_T)$ for $φ$-mesons is larger than that for protons in the low-$p_T$ regions.
Systematic comparisons of jetlike correlation data to radiative and collisional energy loss model calculations are essential to extract transport properties of the quark-gluon medium created in relativistic heavy ion collisions. This paper presents a transport study of collisional broadening of jetlike correlations, by following parton-parton collision history in a multiphase transport (AMPT) model. The correlation shape is studied as a function of the number of parton-parton collisions suffered by a high transverse momentum probe parton ($N_{\rm coll}$) and the azimuth of the probe relative to the reaction plane ($φ_{\rm fin.}^{\rm probe}$). Correlation is found to broaden with increasing $N_{\rm coll}$ and $φ_{\rm fin.}^{\rm probe}$ from in- to out-of-plane direction. This study provides a transport model reference for future jet-medium interaction studies.
Sneha Chandrasekhar, Suresh Pradhan, Madhumita Bhattacharya
et al.
The primary parameters for testing an individual monitoring system are standard deviation and the coefficient of variation. The International Electrotechnical Commission (IEC) standard 62387-1 recommends testing the coefficient of variation of dosemeters for various doses because the acceptable coefficient of variation changes with the dose level. However, for dose quantity Hp(10), i. e. doses greater than 1.1 mSv, the acceptable limit is 5 % and remains unchanged up to the highest dose in the measurable range. This study was carried out to confirm whether the same is followed in the Indian personnel monitoring system when measuring Hp(10) and also in order to study the variation in the coefficient of variation with a given dose. It was observed that even if the coefficient of variation at doses between 0.1 mSv and 1.1 mSv is lower than the IEC requirement, at higher doses, the same may not be true. In routine monitoring, since the anticipated doses are less than 1 mSv, a monitoring system which performs better than the IEC requirement at these levels of doses is an advantage. However, good performance at said dose levels does not naturally indicate good performance at higher doses.
Particle ratios provide insight into the hadrochemistry of the event and the mechanisms for particle production. In Pb-Pb collisions the relative multi-strange baryon yields exhibit an enhancement with respect to pp collisions, whereas the short-lived K$^{*0}$ resonance is suppressed in the most central events due to re-scattering of its decay daughter particles. Measurements in p-Pb allow us to investigate the development of these effects as a function of the system size. We report comprehensive results on light-flavor hadron production measured with the ALICE detector in p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV, covering a wide range of particle species which includes long-lived hadrons, resonances and multi-strange baryons. The measurements include the transverse momentum spectra and the ratios of spectra among different species, and extend over a very large transverse momentum region, from $\approx$100 MeV/$c$ to $\approx$20 GeV/$c$, depending on the particle species.
In this short paper we provide an overview of new results from the ATLAS physics program at the LHC as of spring 2015. We separately summarize the results from p+Pb collisions and Pb+Pb collisions along with some of their interpretations.
In the last years, chiral effective field theory has been successfully developed for and applied to systems with few nucleons. Here, I present a new approach for ab initio calculations of nuclei that combines these precise and systematic forces with Monte Carlo simulation techniques that allow for exact solutions of the nuclear A-body problem. A short introduction of this method is given and a few assorted results concerning the spectrum and structure of 12C and 16O are presented. The framework further allows one to study the properties of nuclei in worlds that have fundamental parameters different from the ones in Nature. This allows for a physics test of the anthropic principle by addressing the question how strongly the generation of the life-relevant elements depends on the light quark masses and the electromagnetic fine structure constant.
We suggest a small set of fission observables to be used as test cases for validation of theoretical calculations. The purpose is to provide common data to facilitate the comparison of different fission theories and models. The proposed observables are chosen from fission barriers, spontaneous fission lifetimes, fission yield characteristics, and fission isomer excitation energies.
Ekaterina Retinskaya, Matthew Luzum, Jean-Yves Ollitrault
We present a combined analysis of elliptic and triangular flow data from LHC and RHIC using viscous relativistic hydrodynamics. Elliptic flow $v_2$ in hydrodynamics is proportional to the participant eccentricity $\varepsilon_2$ and triangular flow is proportional to the participant triangularity $\varepsilon_3$, which means $v_n=C_n\varepsilon_n$, where $C_n$ is the linear response coefficient in harmonic n. Experimental data for $v_2$ and $v_3$ combined with hydrodynamic calculations of $C_n$ thus provide us with the rms values of initial anisotropies $\varepsilon_2$ and $\varepsilon_3$. By varying free parameters in the hydro calculation (in particular the shear viscosity), we obtain an allowed band in the (rms $\varepsilon_2$, rms $\varepsilon_3$) plane. Comparison with Monte-Carlo models of the initial state allows us to exclude several of these models. We illustrate that the effect of changing the granularity of the initial state is similar to changing the medium properties, making these effects difficult to disentangle.
Electromagnetic reactions on light nuclei are fundamental to advance our understanding of nuclear structure and dynamics. The perturbative nature of the electromagnetic probes allows to clearly connect measured cross sections with the calculated structure properties of nuclear targets. We present an overview on recent theoretical ab-initio calculations of electron-scattering and photonuclear reactions involving light nuclei. We encompass both the conventional approach and the novel theoretical framework provided by chiral effective field theories. Because both strong and electromagnetic interactions are involved in the processes under study, comparison with available experimental data provides stringent constraints on both many-body nuclear Hamiltonians and electromagnetic currents. We discuss what we have learned from studies on electromagnetic observables of light nuclei, starting from the deuteron and reaching up to nuclear systems with mass number A=16.
In this paper we present the results of calculations and analyses of the integral particle reflection coefficient of photons for oblique photon incidence on planar targets, in the domain of initial photon energies from 100 keV to 300 keV. The results are based on the Monte Carlo simulations of the photon reflection from water, concrete, aluminum, iron, and copper materials, performed by the MCNP code. It has been observed that the integral particle reflection coefficient as a function of the ratio of total cross-section of photons and effective atomic number of target material shows universal behavior for all the analyzed shielding materials in the selected energy domain. Analytical formulas for different angles of photon incidence have been proposed, which describe the reflection of photons for all the materials and energies analyzed.