M. K. Mehta

Mass absorption coefficients and range of beta particles in Be, Al, Cu, Ag and Pb

It is demonstrated that the practical range of a beta spectrum (Emax=E) in any material can be obtained from mass absorption coefficient (μ/ρ) values. It is further shown that a semiempirical relation likeμ/ρ =AE−B in whichA andB are related to the atomic numberZ, of the absorber can be used for determiningμ/ρ of any material of known atomic numberZ. Theβ particle ranges are compared with theoreticalcsda and practical ranges from literature.

Fluctuations in the integrated cross section of the reaction 45Sc(p, n)45Ti

Abstract The integrated cross section of the reaction 45 Sc(p, n) 45 Ti as a function of incident proton energy has been measured in the energy interval 2.910 to 5.250 MeV with energy steps of 5 keV. The overall energy resolution was about 3.5 keV. The excitation function shows fluctuations around an average. This average increases with proton energy. The statistical theory of Ericson was applied; the autocorrelation was calculated and used to determine the average width of levels in the compound nucleus 46 Ti in the excitation energy range 13.230 to 15.140 MeV. The analysis yields an average width 〈 Γ 〉 of 6 keV corresponding to a compound nucleus lifetime of 1.1. × 10 −7 psec.

Total (p, n) reaction cross section study on51V over the incident energy range 1·56 to 5·53 MeV

The total (p, n) reaction cross section for51V has been measured as a function of proton energy in the energy range 1·56 to 5·53 MeV with thick and thin targets. The fluctuations in the fine resolution excitation functions were analysed, to extract 〈Γ〉, the coherence width. The thick target excitation function suitably averaged over appropriate energy intervals has been compared with the optical model, Hauser-Feshbach and Hauser-Feshbach-Moldauer calculations. The strong isobaric analog resonance atEp ∼ 2·340 has been shape analysed to extract the proton width Γp, the spreading withW and the spectroscopic factor.

Isobaric analogue resonances in the 80Se(p, n)80Br reaction

The toral (p, n) reaction cross section for 80 Se has been measured as a function of proton energy in the energy range from ≈ 2.7 to 5.375 MeV with fine resolution (≈ 5 keV). Several prominent isobaric analogue resonances have been measured. A detailed shape analysis of the isobaric analogue resonances has been performed to determine the proton width Γ p , the spreading width W and the spectroscopic factor S for the various resonances.

A study of the reaction19F(α, n)22Na in the bombarding energy range 2·6 to 5·1 MeV

The total (α, n) reaction cross section for19F has been measured as a function of alpha energy in the energy range 2·6 to 5·1 MeV with a thin target. The excitation function exhibits a large number of resonances. The prominent amongst these for which theJπ values are known have been analysed to extract the partial widthsΓα and Γn. Statistical analysis of the data in terms of strength function and average level spacing distribution has also been performed.

Spectroscopy of50V with (p, nγ) reaction

Information on the low-lying levels up to ∼1.9 MeV excitation of the doubly odd nucleus50V has been obtained through the Ge (Li)-Ge (Li) coincidence study with the50Ti(p, nγ)50V reaction. Branching ratios have been measured and tentative spin-parity assignments have been made. A detailed comparison with other measurements reported recently has also been made. Using the lowest seniority wave functions with (f7/2)p3 (f7/2)n−1 configuration, energy levels and electromagnetic properties have been calculated. These have been compared with the present and earlier experimental data.

Resonance spectroscopy of44Ti in the excitation energy range 9.05 to 10.28 MeV

The absolute differential cross sections for the40Ca(α,α)40Ca reaction have been measured in the bombarding energy range from 4.33 to 5.68 MeV at the four laboratory angles 85°, 125°, 141° and 165°. An analysis of the data using multilevelR matrix theory has provided the spin-parities and widths of 29 levels in the compound nucleus44Ti. A comparison has been made with the levels deduced from the (α,γ) reaction and existing theoretical calculations of44Ti levels.

Reaction48Ca (p, n)48Sc fromE p =1.885 to 5.1 MeV

The total (p, n) reaction cross section for48Ca has been measured as a function of proton energy in the energy range 1.885 to 5.100 MeV with an overall resolution of ∼ 2 keV and in ∼ 5 keV energy steps. The fluctutions in fine resolution data have been analysed to determine the average coherence width 〈Γ〉. The excitation function averaged over large energy intervals has been analyzed in terms of the optical model. The isobaric analogue resonances atEp ∼ 1.95 and 4 MeV have been shape-analyzed to extract the proton partial width and the spectroscopic factorSn. A comparison of the gross structures observed in ∼ 55 keV averaged excitation function with the predictions of Izumo’s partial equilibrium model has also been made.

Two million volt terminal tandem accelerator

Design and construction details of a horizontal 2 MV Tandem Van de Graaff accelerator built at Bhabha Atomic Research Centre are given. A terminal voltage of 2.15 MV has been achieved. Energy analysed Corona stabilized beams of protons and oxygen ions have been obtained. Experiments have been carried out to test the performance of the accelerator.

Structure in the 27Al(p, α)24Mg cross section between Ep = 4.0 and 5.5 MeV

Abstract The excitation functions of the reactions 27 Al(p, α 0 ) 24 Mg and 27 Al(p, α 1 ) 24 Mg ∗ were measured in the proton energy range E p = 4.0–5.5 MeV with an energy resolution of about 5 keV at lab angles of 60°, 90° and 165°. The excitation curves exhibit sharp maxima of widths between 10 and 50 keV superimposed on a broad 150–300 keV wide structure. The channel as well as angle cross correlation functions calculated with moving averages are high for all the cases. This as well as strong visual correlations of the sharp and the broad structure between various curves lead to the conclusion that the observed structure, both fine as well broad, is due to individual resonance effects and not to fluctuations. It is suggested that the fine structure is due to very slightly overlapping compound nuclear levels, while the broad structure may represent the “intermediate states” of the compound system.