arXiv subjects

Tanmoy Bar

Publications and source records attributed to Tanmoy Bar.

10 recordsLinked to original sources

arXiv2026

A systematic approach to Covariance matrix formulation in charged particle activation experiments

This work presents a detailed covariance and correlation matrix analysis for experimentally measured cross sections obtained using the activation technique. Both statistical and systematic contributions to the covariance matrix were explicitly calculated using sensitivity coefficients. The detector efficiency was determined by refitting standard source data with an exponential function, and the associated covariance matrix of the fitted parameters was propagated to estimate the uncertainty in efficiency at the relevant $\gamma$-ray energy. The cross sections and the corresponding experimental parameters, such as beam flux, target thickness, $\gamma$-ray intensity, and decay corrections, were taken from previously published measurements and are used here for the purpose of illustrating the covariance formalism. The resulting covariance and correlation matrices provide a comprehensive representation of uncertainties and their interdependencies. This formalism demonstrates the importance of including correlated uncertainties for reliable interpretation and comparison of experimental cross section data.

nucl-th↗

arXiv2026

Excitation function measurement of $^{144}$Sm($\alpha$,n) reaction at sub-Coulomb energies and detailed covariance analysis

The cross-section measurement of $^{144}$Sm($\alpha$,n)$^{147}$Gd (T$_{1/2}=$38.06(12) h) reaction has been performed at sub-Coulomb energies around 14$-$21 MeV ($V_{coul}\approx 21.8$ MeV) using the stacked foil activation technique. Irradiated targets were prepared from enriched (67\%) $^{144}$Sm$_2$O$_3$ powder using molecular deposition technique between thickness 280$-$350 $\mu$g/cm$^2$ on high purity Al backing. A detailed simulation has been carried out to address the energy uncertainty in the irradiated beam energy followed by a comprehensive discussion of various uncertainties in the form of covariance and correlation matrices. Finally the excitation functions are compared with the previously measured experimental data from literature and the theoretical predictions obtained using Hauser-Feshbach statistical model code.

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arXiv2024

Proton induced reaction on $^{108}$Cd for astrophysical p-process studies

The proton capture cross-section of the least abundant proton-rich stable isotope of cadmium, $^{108}$Cd (abundance 0.89\%), has been measured near the Gamow window corresponding to a temperature range of 3-4 GK. The measurement of the $^{108}$Cd(p,$\gamma$)$^{109}$In reaction was carried out using the activation technique. The cross-section at the lowest energy point of 3T$_9$, E$_p$$^{lab}$= 2.28 MeV, has been reported for the first time. The astrophysical S-factor was measured in the energy range relevant to the astrophysical p-process, between E$_p$$^{cm}$= 2.29 and 6.79 MeV. The experimental results have been compared with theoretical predictions of Hauser-Feshbach statistical model calculations using TALYS-1.96. A calculated proton-optical potential was implemented to achieve better fitting, with different combinations of available nuclear level densities (NLDs) and $\gamma$-ray strength functions in TALYS-1.96. The calculations provided satisfactory agreement with the experimental results. The reaction rate was calculated using the calculated potential in TALYS-1.96 and compared with the values provided in the REACLIB database.

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arXiv2024

Fabrication of $^{108}$Cd target for the astrophysical p-process studies

The detailed process of preparing enriched $^{108}$Cd targets on mylar and copper backing using the vacuum evaporation technique is described. These targets were employed in an experiment to measure the proton capture cross-section at energies significantly below the Coulomb barrier, for the astrophysical p-process studies. Due to the low melting point and high vapor pressure of cadmium, some adjustments were implemented in the Telemark multipocket e-beam setup. The target thickness was determined through the measurement of alpha particle energy loss from a triple alpha source and also by RBS measurements. The thickness of the $^{108}$Cd films varies between 290 to 660 $\mu$g/cm$^2$, with a non-uniformity of approximately 10$\%$. X-ray Photoelectron Spectroscopy (XPS) and X-ray Fluorescence (XRF) analyses were conducted to examine the presence of impurities and to assess surface morphology, phase, and chemical composition.

physics.ins-det↗

arXiv2024

Study of $^{113}$In($\alpha,\alpha$) elastic scattering to determine $\alpha$-optical potential relevant for astrophysical $\gamma$-process

The $\alpha$-optical potential is one of the key input parameters used to measure the reaction rate of the ($\gamma,\alpha$)-process using the Hauser-Feshbach(HF) statistical model and the principle of detailed balance. $\alpha$-elastic scattering experiment on $^{113}$In $p$-nucleus was carried out in the energy range E$_{lab}$=26$-$32 MeV. The vacuum evaporation technique was used to prepare the $^{113}$In target~($\sim$86 $\mu$g/cm$^2$). An energy-dependent local optical potential parameters set was obtained by analysing the experimental elastic scattering angular distribution data. The local potential parameters are extrapolated for lower energies and are used to measure the $^{113}$In($\alpha,\gamma$) reaction cross-section.

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arXiv2024

Experimental study of $\alpha$-induced reactions on $^{113}$In for astrophysical $p$-process

Neutron deficient nuclei from $^{74}$Se$-^{196}$Hg are thought to be produced by $\gamma$-induced reactions ($\gamma$,n), ($\gamma$,p) and ($\gamma,\alpha$) processes. The relatively high abundance of $^{113}$In odd A $p$-nuclei has inspired to study its production processes. As reaction with $\gamma$-beam is difficult to perform in the laboratory, $\gamma$-induced reaction rate is calculated from the inverse reaction data employing reciprocity theorem. Stacked foil activation method was used to measure the $^{113}$In($\alpha,\gamma$) and $^{113}$In($\alpha$, n) reactions cross-section near the astrophysical energies. Theoretical statistical model calculations were performed with different nuclear input parameters and compared with the experimental results. An appropriate $\alpha$-optical potential has been identified from the ($\alpha,\gamma$) and ($\alpha$, n) fitting, which provides the major source of uncertainty in the statistical model calculations. The other nuclear input parameters like level density, and $\gamma$-ray strength function were also constrained for theoretical calculations. $^{113}$In($\alpha,\gamma$)$^{117}$Sb and $^{117}$Sb($\alpha,\gamma$)$^{113}$In reaction rates were calculated using best-fitted input parameters.

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arXiv2024

Measurement of $^{144}$Sm(p,$\gamma$) cross-section at Gamow energies

The cross-section measurement of $^{144}$Sm(p, $\gamma$)$^{145}$Eu (T$_{1/2}=$5.93(4) days) reaction has been performed at proton energies around 2.6, 3.1, 3.7, 4.1, 4.2, 4.7, 5.1, 5.5, 5.9, 6.4, 6.8 MeV using the activation technique. These energies correspond to the Gamow window for 3, 4 GK and a partial portion for 2 GK. $^{144}$Sm has been chosen for the present study because of its significantly higher abundance compared to the other neighboring $p$-nuclides (Z $>$ 50). The astrophysical $S-$factor of this reaction has been measured for the first time at E$^{cm}_p=$ 2.57$\pm$0.13 MeV, $S-$ factor$=$2.542$\pm$1.152($\times$10$^{10}$) MeV-b. Cross-section data were compared with the previously measured experimental data from literature and the theoretical predictions obtained using Hauser-Feshbach statistical model codes TALYS 1.96 and NON-SMOKER. A satisfactory agreement between experimental data and theoretical results was observed. Molecular deposition technique was used to prepare the $^{144}$Sm targets having thickness between 100$-$350 $\mu$g/cm$^2$ on Al backing. Obtained results were utilized to predict the reaction rates for $^{144}$Sm (p, $\gamma$) and $^{145}$Eu ($\gamma$, p) reactions using TALYS 1.96 and the reciprocity theorem.

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arXiv2022

Investigation of long lived activity produced due to neutron emitting reactions

In this article, a detailed investigation has been done for the long lived gamma activity due to neutron emitting experiments. These calculations mainly focused on the experiments used for energy calibration purposes. Calibrated energy is one of the most essential features of any accelerator facility. Several experiments have been used for this purpose. Generally, experiments having sharp curvature change in cross section of yield are used. Neutron emitting experiments are one of such. Around the globe reactions like $^7Li(p,n)$, $^{13}C(p,n)$, $^{19}F(p,n)$, $^{27}Al(p,n)$ etc. are used to calibrate energy of the beam with accelerator terminal voltage. Neutrons coming from these experiments can interact with surrounding elements. These interactions with neutrons can create long lived gamma activity which may interfere with future measurements. The present study has been done keeping in mind the new Facility for Research in Experimental Nuclear Astrophysics (FRENA) at Saha Institute of Nuclear Physics. It is a 3MV tandetron low energy high current machine.

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arXiv2020

A simple method to prepare deuterated targets for experiments relevant to nuclear astrophysics

In this work, a simple and efficient thin ($50- 350μg/cm^2$) deuterated polyethylene target preparation method is described. The method of easy removal of thin targets from casting surface without using any cryogenic freezing has been described. The difference in thermal expansion properties is used to separate films from glass slides. 3-$α$ radioactive source is used to measure the target thickness. The material property of the prepared targets is verified by Attenuated total reflection (ATR) method.

physics.ins-det↗

arXiv2020

Simulation of heat transfer and dissipation in targets used in nuclear astrophysics experiments

This work presents time-dependent numerical calculations of heat generation and dissipation in targets used in high ion-beam current nuclear astrophysics experiments. The simulation is beneficial for choosing the thickness of targets, maximum ion-beam current and design setup for cooling of such targets. It is found that for the very thin target ($^{27}Al(p,p),^{12}C(p,p)$) heat generation inside target is relatively low and a fair amount of high current (few $μ$A)can be used without any melting issue. But in case of thick targets ($^{27}Al(p,γ),^{12}C(p,γ)$) cooling became essential for the survival of reaction target.

physics.ins-det↗