H C MANJUNATHA
Articles written in Pramana – Journal of Physics
Volume 89 Issue 3 September 2017 Article ID 0042 Research Article
Gamma dosimetric parameters in some skeletal muscle relaxants
We have studied the attenuation of gamma radiation of energy ranging from 84 keV to 1330 keV $(^{170}Tm, ^{22}Na, ^{137}Cs, and ^{60}Co)$ in some commonly used skeletal muscle relaxants such as tubocurarine chloride, gallamine triethiodide, pancuronium bromide, suxamethonium bromide and mephenesin. The mass attenuation coefficient is measured from the attenuation experiment. In the present work, we have also proposed the direct relation between mass attenuation coefficient $(\mu/\rho)$ and mass energy absorption coefficient $(\mu_{en}/\rho)$ based on the nonlinear fitting procedure. The gamma dosimetric parameters such as mass energy absorption coefficient $(\mu_{en}/\rho)$, effective atomic number $\rm{(Z_eff )}$, effective electron density $(N_\rm{el})$, specific $\gamma$-ray constant, air kerma strength and dose rate are evaluated from the measured mass attentuation coefficient. These measured gamma dosimetric parameters are compared with the theoretical values. The measured values agree with the theoretical values. The studied gamma dosimetric values for the relaxants are useful in medical physics and radiation medicine.
Volume 90 Issue 5 May 2018 Article ID 0062 Research Article
Parametrisation of the experimental fusion–fission cross-sections
We have presented non-linear analytical formula for fusion–fission cross-sections. This is achieved by analysing many fusion–fission experiments of the compound nuclei of atomic number range $23 \leq Z \leq 146$ available in literature. Our parametrised formula can reproduce the fusion–fission cross-sections which agree well with the experiments. Our parametrisations depend on the charges and masses of the compound nuclei and fission fragments only. These results can be used as a guideline for estimating the fusion–fission cross-sections in those cases where measurements do not exist and also for studying new nuclei which are not yet explored.
Volume 93 Issue 5 November 2019 Article ID 0081 Research Article
Systematic study of the $\alpha$ decay properties of actinides
G R SRIDHARA H C MANJUNATHA K N SRIDHAR H B RAMALINGAM
This work analyses the $\alpha$ decay properties of actinides. Geiger–Nuttall plots are presented for actinides. We have studied the competition between $\alpha$ decay and spontaneous fission and have identified the dominant decay mode. The results have been compared with experiments and they agree well with those of the experiments.
Volume 94 All articles Published: 5 September 2020 Article ID 0136 Research Article
Empirical formula for beta-particle-induced bremsstrahlung yields
We have measured the $\beta$-particle-induced bremsstrahlung energy yield and photon yield in the energy range 0.1668–2.274 MeV using beta sources such as $^{35}$S (0.1668), $^{99}$Tc (0.293), $^{147}$Pm (0.225), $^{90}$Sr(0.5462), $^{204}$Tl (0.76), $^{91}$Y (1.5), $^{32}$P (1.71) and $^{90}$Y (2.274 MeV) in thick targets of atomic number range $13< Z< 83$. We have used a NaI(Tl) detector to measure the bremsstrahlung radiations. Based on the experimental results, we have constructed a semiempirical formula for $\beta$-particle-induced bremsstrahlung energy yield and photon yield. This formula produces bremsstrahlung energy yield and photon yield in the energy range 0.1668 MeV$ < E_{\rm{max}} < 2.274$ MeV for thick targets within the atomic number range $13 < Z < 83$. The values produced by the present formula are compared with the experiments.
Volume 95 All articles Published: 16 November 2021 Article ID 0194 Research Article
Decay of dinuclear systems formed from dubnium
A M NAGARAJA H C MANJUNATHA N SOWMYA P S DAMODARA GUPTA S ALFRED CECIL RAJ
The radioactivity of the superheavy nuclei ${}^{250−275}$Db is studied and presented using the Coulomb and proximity potentials. The half-lives corresponding to different decay modes such as α, cluster decay (${}^{12}$C, ${}^{14}$N,${}^{18,20}$O, ${}^{23}$F, ${}^{20}$Ne, ${}^{34}$S, ${}^{28}$Mg and ${}^{40}$Ca) and spontaneous fission in the superheavy nuclei ${}^{250−275}$Db are studied. The studied half-lives are compared with the available experiments. The decay modes and the branching ratios of isotopes of dubnium are presented. The isotopes of dubnium, ${}^{254−263}$Db, are identified as α emitters, whereas isotopes such as ${}^{250−253}$Db and ${}^{264−275}$Db are identified as having spontaneous fission. The identified alpha emitting isotopes of dubnium have decay energies from 6 MeV to 10 MeV and half-lives 1 ms to 100 s. The possible projectile–target combinations to synthesise the superheavy nuclei ${}^{253−263}$Db were predicted. The fusion of spherical projectile and target yields larger evaporation residue cross-sections.
Volume 96 All articles Published: 20 April 2022 Article ID 0084 Research Article
Search for a viable nucleus–nucleus potential in heavy-ion nuclear reactions
T NANDI D K SWAMI P S DAMODARA GUPTA YASH KUMAR S CHAKRABORTY H C MANJUNATHA
We have constructed empirical formulae for the fusion and interaction barriers using a large number of experimental values
chosen randomly from the literature available till date. The obtained fusion barriers have been compared with different model
predictions based on the proximity, Woods–Saxon and double folding potentials along with several empirical formulas,
time-dependent Hartree–Fock theories and experimental results. The comparison allows us to find the best model,
which is nothing but the present empirical formula only. Most remarkably, the fusion barrier and radius show excellent
consonance with the experimental findings for the reactions meant for the synthesis of super heavy elements also. Furthermore,
it is seen that substitution of the predicted fusion barrier and radius in classic Wong formula (Wong,
Volume 96 All articles Published: 4 August 2022 Article ID 0146 Research Article
Heavy ion fusion with lead and bismuth targets
P S DAMODARA GUPTA H C MANJUNATHA N SOWMYA L SEENAPPA N MANJUNATHA T GANESH
The cold fusion reactions with lead and bismuth as targets were used in the synthesis of superheavy elements (SHE) with mass number up to 113. Researchers ignored the cold fusion reactions in the synthesis of SHE>113. This may be due to the improper choice of projectiles. The present study focusses on cold fusion reactions leading to the formation of SHE from Z = 112 to 126. Suitable projectiles for the fusion reaction using $^{208}$Pb and $^{209}$Bi targets were identified. The fusion and evaporation residue cross-sections are evaluated usingadvance statistical model. The produced cross-sections were compared with the available experiments. Suitable projectiles for synthesising the superheavy elementswith Z = 104–126 using lead and bismuth targets are predicted.The predicted production cross-sections vary from nanobarn (nb) to picobarn (pb). The use of spherical–spherical projectile and target yields larger cross-sections than spherical–deformed or deformed–spherical projectile andtarget combination.
Volume 96 All articles Published: 26 October 2022 Article ID 0214 Research Article
P S DAMODARA GUPTA H C MANJUNATHA N SOWMYA T GANESH
We have systematically studied quasifission (QF) and fusion–fission (FF) lifetimes for heavy ion fusion reactions which were used in the synthesis
of superheavy elements (SHEs) 104 to 118 as well as attempted to synthesise SHEs 119 and 120 using the DNS model. The dependence of QF on energy, angular momentum,
entrance channel parameters, deformation parameters and orientation angles are studied. The study reveals that QF lifetimes are larger for the successful reactions than for the
unsuccessful reactions. It is also observed that the study of FF lifetimes of both successful and unsuccessful reactions will not give any clue for the reason of failure of experiments
to synthesise superheavy elements. It is also observed that the QF process can be controlled by the projectile of lightly deformed or spherical nuclei. The present study finds the importance
in selecting the projectile–target combination for the synthesis of SHEs with
Volume 96 All articles Published: 10 December 2022 Article ID 0230 Research Article
On the time-scale of quasifission and Coulomb fission
T NANDI H C MANJUNATHA P S DAMODARA GUPTA N SOWMYA N MANJUNATHA K N SRIDHARA L SEENAPPA
The Coulomb fission may take place in a reaction if the maximum Coulomb excitation energy transfer exceeds the fission barrier of either the projectile or the target nucleus. This condition is satisfied in all the reactions used for the earlier blocking measurements of fission time-scale except for the reaction $^{208}$Pb + natural Ge crystal, where the time-scale is below the measurement limit of the blocking technique $\les$ 1 as. Inclusion of Coulomb fission in the data analysis of the blocking experiments leads us to interpret the measured time-scales longer than a few attoseconds (as) (about 1–2.2 as) due to slow Coulomb fission and those shorter than 1 as, as due to quasifission and fast Coulomb fission. Consequently, this finding resolves the critical discrepancies between the fission time-scales measured using the nuclear and blocking techniques. This, in turn, validates the fact that the quasifission and fast Coulomb fission time-scales are indeed of the order of zeptosecond (zs) in accordance with the nuclear experiment sand theories. The present results thus provide an essential input to the understanding of the fusion evaporation reaction during the formation of heavy elements.
Volume 97 All articles Published: 23 December 2022 Article ID 0012 Research Article
An accurate empirical formula for the average total kinetic energy released in fission
H C MANJUNATHA N SOWMYA K N SRIDHAR L SEENAPPA P S DAMODARA GUPTA
The empirical formulae for an average total kinetic energy released during the symmetric and asymmetric fission has been estimated by considering the recently available experimental data.
An empirical formulae is deduced by the systematic variation of $\langle$E
Volume 97, 2023
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