# Bhoomika MaheshwariUniversity of Zagreb · Department of Physics (PMF)

Bhoomika Maheshwari

Doctor of Philosophy

## About

71

Publications

6,947

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203

Citations

Citations since 2016

Introduction

Miles to go before I learn everything about nuclear isomerism!!

Additional affiliations

October 2021 - February 2022

**Indian Institute of Technology Ropar**

Position

- Post-Doc Fellow

January 2020 - September 2021

**Amity Institute of Nuclear Science and Technology**

Position

- PostDoc Position

December 2018 - December 2019

Education

July 2011 - September 2016

July 2009 - June 2011

## Publications

Publications (71)

The similar behavior of the B(E1) values of the recently observed 13- odd
tensor E1 isomers and the B(E2) values of the 10+ and 15- even tensor E2
isomers in the Sn-isotopes has been understood in terms of the generalized
seniority for multi-j orbits by using the quasi-spin scheme. This simple
approach proves to be quite successful in explaining th...

Symmetries are known to play an important role in the low lying level structure of Sn isotopes, mostly in terms of the seniority and generalized seniority schemes. In this paper, we revisit the multi-j generalized seniority approach for the first excited 2 + and 3 − states in the Cd (Z = 48), Sn (Z = 50) and Te (Z = 52) isotopes, where the Cd and T...

The puzzle of finding consistent nuclear configurations for explaining both the decay probabilities and moments of the 9/2 − , 8 + and 21/2 − isomers in and around N = 126 closed shell has been approached in the generalized seniority scheme. Though h 9/2 is the dominant orbital near Fermi energy, the role of configuration mixing from the surroundin...

We present an updated version of the 2015-Atlas of Nuclear Isomers \cite{jain2015}, compiling and evaluating experimental data for the isomers with half-life $\ge 10$ $\it{ns}$, together with their spectroscopic properties such as excitation-energies, half-lives, decay modes, spins and parities, energies and multipolarities of isomeric transitions,...

Realistic nuclear level densities (NLDs) obtained within the spectral distribution method (SDM) are employed to study nuclear processes of astrophysical interest. The merit of SDM lies in the fact that the NLDs corresponding to many body shell model Hamiltonian consisting of residual interaction can be obtained for the full configurational space wi...

We present an updated version of the 2015-Atlas of Nuclear Isomers (Jain et al., 2015), compiling and evaluating experimental data for the isomers with half-life ≥ 10 ns, together with their spectroscopic properties such as excitation-energies, half-lives, decay modes, spins and parities, energies and multipolarities of isomeric transitions, along...

The negative-parity band structure built on the proton h9/2 state in Tl199 has been established up to an excitation energy of 7 MeV and spin of (51/2)ℏ. The level scheme has been extended with the inclusion of fourteen new transitions de-exciting levels at high spin. The ΔI=1 γ rays are found to be more prominently visible in the spectra when compa...

Realistic nuclear level densities (NLDs) obtained within the spectral distribution method (SDM) are employed to study nuclear processes of astrophysical interest. The merit of SDM lies in the fact that the NLDs corresponding to many body shell model Hamiltonian consisting of residual interaction can be obtained for the full configurational space wi...

The puzzle of finding consistent nuclear configurations for explaining both the decay probabilities and moments of the ${9/2}^-$, ${8}^+$ and ${21/2}^-$ isomers in and around $N=126$ closed shell has been approached in the generalized seniority scheme. Though $h_{9/2}$ is the dominant orbital near Fermi energy, the role of configuration mixing from...

The variation of total nuclear level densities (NLDs) and level density parameters with proton number Z are studied around the β-stable isotope, Z 0 , for a given mass number. We perform our analysis for a mass range A=40 to 180 using the NLDs from popularly used databases obtained with the single-particle energies from two different microsopic mas...

The variation of total nuclear level densities (NLDs) and level density parameters with proton number $(Z)$ are studied around the $\beta$-stable isotope, $Z_{0}$, for a given mass number. We perform our analysis for a mass range $A=40$ to 180 using the NLDs from popularly used databases obtained with the single-particle energies from two different...

Nuclear isomers are the long-lived excited states of nuclei. Therefore, they constitute the meta-stable landscape of nuclei. The first isomer was probably identified as early as 1921. Since then, the number of isomers has been growing steadily picking up pace in recent times.
Interest in nuclear isomers has grown in recent years for many reasons....

In this paper, we investigate the generalized seniority scheme and the validity of Generalized Seniority Schmidt Model in and around the Z = 82 semi-magic region. A consistently same multi-j configuration is used to explain all the nuclear spectroscopic properties such as g−factors, Q−moments and B(E2) trends for the ${13/2}^ +$ , ${12}^ +$ and ${3...

In this paper, we investigate the generalized seniority scheme and the validity of Generalized Seniority Schmidt Model in and around the $Z=82$ semi-magic region. A consistently same multi-j configuration is used to explain all the nuclear spectroscopic properties such as $g-$factors, $Q-$moments and $B(E2)$ trends for the ${13/2}^+$, ${12}^+$ and...

Spin isomers or spin traps represent the most dominant class of isomers observed across the whole chart of nuclides. When the decay process is primarily suppressed by a large change in angular momentum and/or small decay energy, it leads to a longer half-life for the excited state, and hence, the spin isomers. Their occurrence and decay may be unde...

Nuclear isomers currently occupy the centre stage in nuclear physics research. Recent developments in nuclear detectors, rare beam facilities, reaction analyzers, and digital electronics as well as computational power, make it possible to observe new isomers, and measure their detailed properties.

Nuclear isomers have turned out to be very useful tool in both the fundamental researches, as well as practical applications. Their use in uncovering the nuclear structure of nuclei is now well recognized and will be discussed with a few selected examples, where novel experimental techniques are being continuously devised and used. With the advent...

In this chapter, we briefly describe those examples of isomers which are rather unusual in any of their specific characteristics or properties. These isomers, which carry a property like half-life, spin, excitation energy at the extreme, either very low or very high, are being termed as extreme isomers. Such isomers generate a tremendous sense of e...

Recent developments in the experimental techniques have enabled the discovery of a number of K-isomers in a broad range of mass regions. The variety of K-isomers offer new possibilities in both fundamental research as well as new applications. Their studies offer unique insight into the interplay between intrinsic and collective motion in nuclei.

It is now well known that a nucleus may have various kinds of shapes, from simple spherical to complex deformed, depending upon the N, Z configuration, excitation energy, angular momentum etc. These distinct shapes arise because of the additional minima in the potential energy of the nucleus besides the ground state minimum, when plotted against th...

The real life situation in nuclei may involve many active orbitals in their valence space. These orbitals may have many j-values. It is, therefore, imperative that the seniority concept as introduced in the last chapter should be generalized to multi-j environment. We, therefore, present in this chapter a generalization of the seniority scheme, and...

This chapter is devoted to the seniority isomers, which are generally found in spherical or nearly spherical semi-magic nuclei. It is rather unusual that a quantity like seniority introduced purely on theoretical grounds, merely to distinguish states having same quantum numbers, should become so important to understand a class of nuclear excitation...

We revisit the studies of the isotopic shift in the charge radii of {\it even-even} isotopes of Sn and Pb nuclei at $N$ = 82, and 126, respectively, within the relativistic mean-field and Relativistic-Hartree-Bogoliubov approach. The shell model is also used to estimate isotopic shift in these nuclei, for the first time, to the best of our knowledg...

A detailed investigation on the relative isotopic distributions has been carried out for the first time in case of even-even correlated fission fragments for the 235 U(n_{th} ,f) fission reaction. High-statistics data were obtained in a prompt γ ray spectroscopy measurement during the EXILL campaign at ILL, Grenoble, France. The extensive off-line...

A detailed investigation on the relative isotopic distributions has been carried out for the first time in case of even-even correlated fission fragments for the $^{235}$U($n_{th}$,$f$) fission reaction. High-statistics data were obtained in a prompt $\gamma$ ray spectroscopy measurement during the EXILL campaign at ILL, Grenoble, France. The exten...

We revisit the studies of the isotopic shift in the charge radii of even-even isotopes of Sn and Pb nuclei at N = 82, and 126, respectively, within the relativistic mean-field and Relativistic-Hartree-Bogoliubov approach. The shell model is also used to estimate isotopic shift in these nuclei, for the first time, to the best of our knowledge. The g...

Nuclear isomers are the long-lived excited states of nuclei. Therefore, they constitute the meta-stable landscape of nuclei. The first isomer was probably identified as early as 1921. Since then, the number of isomers has been growing steadily picking up pace in recent times.
Interest in nuclear isomers has grown in recent years for many reasons....

We present our concise notes for the lectures and tutorials on pairing, quasi-spin and seniority delivered at SERB school on Role of Symmetries in Nuclear Physics, AMITY University, $2019$. Starting with some generic features of residual nucleon-nucleon interactions, we provide detailed derivation of the matrix elements for the $\delta$-interaction...

We present our concise notes for the lectures and tutorials on pairing, quasi-spin and seniority delivered at SERB school on Role of Symmetries in Nuclear Physics, AMITY University, 2019. Starting with some generic features of residual nucleon-nucleon interactions, we provide detailed derivation of the matrix elements for the δ-interaction which is...

In the present paper, we explore the idea of isospin conservation in new situations and contexts based on the directions provided by our earlier works. We present the results of our calculations for the relative yields of neutron-rich fission fragments emitted in fast neutron-induced fission, 238U (n, fission) reaction by using the concept of the c...

We present a study of the spectroscopic factors for the (d,p) stripping reactions to the ${11/2}^-$ states in the chain of odd-mass Sn (A = 115 - 131) isotopes by using a multi-j generalized seniority approach. The results are in line with realistic shell model calculations and explain the experimental trend quite well. The multi-j configuration us...

We study the quadrupole moments and the B(E2; 2 + → 0 +) values for the 11/2 − states and the first 2 + states, respectively, by using a multi-j generalized seniority approach in the Cd (Z = 48), Sn (Z = 50) and Te (Z = 52) isotopic chains. The g-factor trends have also been discussed. Although, Cd and Te isotopes represent two-proton hole and two-...

We study the quadrupole moments and the B(E2; $2^+ \rightarrow 0^+$) values for the ${11/2}^-$ states and the first $2^+$ states, respectively, by using a multi-j generalized seniority approach in the Cd (Z = 48), Sn (Z = 50) and Te (Z = 52) isotopic chains. The g-factor trends have also been discussed. Although, Cd and Te isotopes represent two-pr...

The neutron-rich nuclei 130Cd and 206Hg, so important in the astrophysical processes, may also be useful in tracking the evolution of nuclear shell gaps as one traverses the neutron-rich region. The high spin 8+ isomer in 130Cd and the 10+ isomer in 206Hg turn out to be the lampposts, which may shed light on the shell gaps and validity of the senio...

We have recently applied the generalized seniority approach successfully to explain the B(E1)/B(E2)/B(E3) properties of the semi-magic nuclei. In the present paper, we extend this approach to the Schmidt model as Generalized Seniority Schmidt Model and calculate the g-factors of the various seniority states in the semi-magic nuclei. We find that th...

Seniority has proved to be a unique and simple probe to address some of the complex issues underlying nuclear structure of nuclei close to magic numbers. An extension from the concept of seniority in single-j shell to generalized seniority in multi-j shell has recently been provided by us. We have, consequently, established new selection rules for...

We show that the gross features of the relative yields of neutron-rich fission fragments emitted in heavy ion induced fusion-fission reactions $^{208}$Pb ($^{18}$O, f) and $^{238}$U ($^{18}$O, f) may be understood by using the concept of isospin and its conservation during the process of fission. The goodness of isospin derives from the neutron ric...

We have recently applied the generalized seniority approach successfully to explain the B(E1)/B(E2)/B(E3) properties of semi-magic nuclei. In the present paper, we extend this approach to the Schmidt model as Generalized Seniority Schmidt Model and calculate the g-factors in semi-magic nuclei. We find that the magnetic moments and the g-factors do...

The generalized seniority approach proposed by us to understand the B(E1)/B(E2)/B(E3) properties of semi-magic nuclei has been widely successful in the explanation of the same and has led to an expansion in the scope of seniority isomers. In the present paper, we apply the generalized seniority scheme to understand the behavior of g-factors in semi...

The generalized seniority approach proposed by us to understand the B(E1)/B(E2)/B(E3) properties of semi-magic nuclei has been widely successful in the explanation of the same and has led to an expansion in the scope of seniority isomers. In the present paper, we apply the generalized seniority scheme to understand the behavior of g-factors in semi...

Seniority has proved to be a unique and simple probe to address some of the complex issues underlying nuclear structure of nuclei close to magic numbers. An extension from the concept of seniority in single-j shell to generalized seniority in multi-j shell has recently been provided by us. We have, consequently, established new selection rules for...

We show for the first time that the generalized seniority scheme explains reasonably well the B(E3) systematics for the \((0^+ \rightarrow 3_1^-)\) transitions in the Sn isotopes, which are odd-tensor E3 transitions connecting different seniority states (\(\Delta v = 2\)). Additionally, we also present large scale shell model (LSSM) calculations to...

We show for the first time that the generalized seniority scheme explains reasonably well the B(E3) systematics for the (0 + → 3 − 1) transitions in the Sn-isotopes, which are odd-tensor E3 transitions connecting different seniority states (∆v = 2). Additionally, we also present Large Scale Shell Model (LSSM) calculations to support our interpretat...

Isomeric studies in neutron-rich nuclei present a powerful tool to explore the structure at the nuclear extremes. In this paper, we discuss the systematic features of the excitation energies and the transition probabilities of Sn isotopes in the region N = 82 to 132 and present their basic understanding in terms of generalized seniority. We further...

Symmetry plays an important role in understanding the nuclear structure properties from the rotation of a nucleus to the spin, parity and isospin of nuclear states. This simplifies the complexity of the nuclear problems in one way or the other. Seniority is also a well known quantum number which arises due to the symmetry in the pairing interaction...

Isomeric studies in neutron-rich nuclei present a powerful tool to explore the structure at the nuclear extremes. We recently used the shell model calculations with Renormalized Charge Depen- dent Bonn (RCDB) effective interaction to calculate the properties of the $6^+$ seniority isomers in $^{134-138}$Sn in an attempt to resolve the anomalous B(E...

In our recent paper [Phys. Lett. B 753, (2016) 122], we have shown that both the odd and even tensor electric transition probabilities exhibit similar behavior within the generalized seniority scheme in a multi-j environment. This microscopic approach was used to show for the first time the occurrence of seniority isomers in the $ {13}^-$ isomers o...

In this talk, we mainly focus on the nuclear isomers in semi-magic nuclei with specific emphasis on the Sn isotopes. The Sn isotopes present the longest chain of isotopes with experimental data available from the doubly magic 100Sn to the doubly magic 132Sn and beyond up to 138Sn. This range of isotopes covers many sub-sets of active valence orbita...

Recent observation of the 6+ seniority isomers and measurements of the B(E2) values in the 134–138Sn isotopes lying close to the neutron drip line have raised some questions about the validity of the currently used effective interactions in the neutron-rich region. Simpson et al. [Phys. Rev. Lett. 113, 132502 (2014)] had to modify the diagonal and...

Negative parity high-spin states of Cd107 have been investigated using the reaction Zr94(18O,5n), from the γ-ray coincidence events recorded by the Indian National Gamma Array. A magnetic dipole (M1) band structure was established for the first time in this nucleus decaying to the low-spin states via several paths. Lifetimes of five in-band levels...

High-spin states in the doubly-odd 198Bi nucleus have been studied by using the 185,187Re(16O,xn) reactions
at a beam energy of 112.5 MeV. γ-γ coincidences, directional correlation ratio, and integrated polarization
asymmetry ratio were measured by using the INGA array with 15 Compton-suppressed clover high-purity
germanium (HPGe) detectors. Defini...

We present a comparative study of the high-spin 11/2−, 10+ and 27/2− nuclear isomers, observed commonly in the full semi-magic Z = 50 isotopic and N = 82 isotonic chains, which are found to display nearly identical systematics in excitation energy and half-lives. A constant and particle number independent energy gap of � ~ 4 MeV between the 0+ grou...

High-spin states in the doubly-odd $^{198}$Bi nucleus have been studied by
using the $^{185,187}$Re($^{16}$O, xn) reactions at the beam energy of 112.5
MeV. $\gamma-\gamma$ coincidence were measured by using the INGA array with 15
Compton suppressed clover HPGe detectors. The observed levels have been
assigned definite spin-parity. The high spin st...

On the occasion of the 75th75th anniversary of the fission phenomenon, we present a surprisingly simple result which highlights the important role of isospin and its conservation in neutron rich fission fragments. We have analysed the fission fragment mass distribution from two recent heavyion reactions 238U(18O,f) and 208Pb(18O,f) as well as a the...

## Questions

Question (1)

I am particularly interested in Sn region/ semi-magic nuclei. Any relevant reference will be appreciated.

## Projects

Projects (5)

Calculation of realistic nuclear level densities (NLDs) using the spectral distribution method (SDM) and study of nuclear processes of astrophysical interest using these NLDs.