• H C Jain

Articles written in Pramana – Journal of Physics

• Four quasi-particle level at 2256 keV in182Re

In-beam nuclear spectroscopic studies of182Re, following the reaction181Ta(α, 3n)182Re have been made using gamma-ray and internal conversion electron techniques.K-conversion coefficients for several transitions have been measured and the multi-polarities of the various transitions assigned. In particular, the spin and parity of the four-quasi-particle isomeric level at 2256 keV were determined to be 16. Theg-factor of this level has been measured to beg = 0·32 ± 0·05. On the basis of theg-factor and the decay pattern of this level, a configuration {v9/2+ [624↑]v7/2 [514↓]v7/2 [503↑]π9/2 [514↑]}kx = 16 has been assigned to this level. The nature of the retardation of the gamma transitions deexciting this level is discussed. It is argued that the measured retardation factors can be explained if the nucleus has a triaxial shape.

• A multi NaI(Tl) detector array for medium energyγ-ray spectroscopy

An array of seven hexagonal NaI(Tl) detectors has been set up for measuringγ-ray spectra in the energy region 5 MeV ≤Eγ ≤ 40 MeV with good accuracy. This is in contrast to earlier set ups which mostly used one large sized (about 10 inchesφ × 15 inches long)NaI(Tl) detector. This set up has been made for the study ofγ decay of GDR based on high spin states and ultra-dipole radiations.

The array has been provided with the following features: a) TOF discrimination against neutrons, b) pile up detection and elimination, c) active and passive shielding to cut down background and d) an array of trigger counters for multiplicity dependence measurements. The well known program EGS4 has been used to determine the response of the array forγ-rays in the energy region 5–40 MeV and several test measurements have been carried out to confirm the validity of the calculated response functions. Some typicalγ-ray spectra fromα and16O induced reactions measured at VECC, Calcutta and Pelletron accelerator at TIFR are also shown.

• A plunger set-up for measuring picosecond nuclear half-lives

A plunger set-up has been designed and constructed to measure picosecond nuclear half-lives using recoil distance method (RDM). The system has been used to measure the half-lives of nuclear states in35Cl,37,38Ar and40K. The shortest half-life measured with the system isT1/2=0.36(14) ps for the 4366 keV (8+) state and the longest half-life isT1/2=1.10(7) ns for the 2543 keV (7+) state in40K.

• Yields of evaporation residues and average angular momentum in heavy ion induced fusion reactions leading to compound nucleus96Ru

Cross-sections for production of evaporation residues from the compound nucleus96Ru* formed by fusion reactions28Si+68Zn,32S+64Ni,37Cl+59Co and45Sc+51V have been obtained from the yields of their characteristicγ-rays. The measurements span an excitation energy range of 55 MeV to 70 MeV of the compound nucleus. The evaporation residue (ER) cross-sections have been analysed in terms of statistical model for the decay of the compound nucleus. A good agreement is found between statistical model calculation and the experimental evaporation residue cross-sections in all the four cases. It is shown that the average angular momentum$$\bar \ell$$ of the compound nucleus can be deduced from a comparison of the experimentally measured and the statistical model predictions for the ER cross-sections. The validity of this method of deriving$$\bar \ell$$ has been discussed for the case of16O+154Sm system.

• Nuclear structure and Indian Clover array

A brief description of the nuclear structure studies performed with the 14-UD pelletron at TIFR has been presented. The experimental facilities developed for these studies are described. Some of the interesting results obtained for mass 70 to 80 nuclei are presented. The development of a recoil mass spectrometer and an Indian clover array for the study of high spin states in nuclei near drip lines is discussed.

• Fabrication and testing of the recoil mass spectrometer at Bombay Pelletron

A recoil mass spectrometer (RMS) has been designed, fabricated and installed at the 15° S beam-line of the Pelletron at TIFR. The RMS consists of a quadrupole doublet just after the target chamber followed by an ‘electrostatic deflector’, a magnetic dipole and a second electrostatic deflector. The recoils produced in the 12C + 58Ni reaction using 60 MeV 12C beam were focussed with the help of electric and magnetic fields and detected in a strip detector placed at the focal plane of the RMS. Further testing of the spectrometer to obtain mass resolution and efficiency are in progress.

• # Pramana – Journal of Physics

Current Issue
Volume 93 | Issue 6
December 2019

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019