Ashok Goswami

Measurement of the neutron capture cross-section of 238U using the neutron activation technique

The 238U(n, γ)239U reaction cross-section at average neutron energy of 3.7xa0±xa00.3xa0MeV from the 7Li(p, n)7Be reaction has been determined using activation and off-line γ-ray spectrometric technique. The 238U(n, γ)239U and 238U(n, 2n)237U reaction cross-sections at average neutron energy of 9.85xa0±xa00.38xa0MeV from the same 7Li(p, n)7Be reaction have been also determined using the above technique. The experimentally determined 238U(n, γ)239U and 238U(n, 2n)237U reaction cross-sections were compared with the evaluated data of ENDF/B-VII, JENDL-4.0, JEFF-3.1 and CENDL-3.1. The experimental values were found to be in general agreement with the evaluated value based on ENDF/B-VII, and JENDL-4.0 but not with the JEFF-3.1 and CENDL-3.1. The present data along with literature data in a wide range of neutron energies were interpreted in terms of competition between different reaction channels including fission. The 238U(n, γ)239U and 238U(n, 2n)237U reaction cross-sections were also calculated theoretically using the TALYS 1.2 computer code and were also found to be in agreement experimental data.

Independent isomeric-yield ratio of 89m,gNb from 93Nb(γ, 4n), natZr(p, xn), and 89Y(α, 4n) reactions

The independent isomeric-yield ratios of 89m,gNb for the 93Nb(γ, 4n) 89m,gNb reaction with bremsstrahlung energies of 45-, 50-, 55-, 60-, and 70-MeV were measured by the activation and the off-line γ-ray spectrometric technique at 100xa0MeV electron linac of the Pohang accelerator laboratory. The isomeric-yield ratios of 89m,gNb for the natZr(p, xn) 89m,gNb and the 89Y(α, 4n) 89m,gNb reactions were measured by using a stacked-foil activation technique with the proton energies of 19–45xa0MeV and alpha energies of 38.9-, 40.5-, and 42.5-MeV at the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences. The measured isomeric-yield ratio of 89m,gNb from the 93Nb(γ, 4n), natZr(p, xn), and 89Y(α, 4n) reactions were compared with the similar literature data in the 89Y(3He, 3n) reaction. It was found that the isomeric yield ratio of 89m,gNb increases with projectile energy, which indicate the effect of excitation energy. However, for the similar compound nucleus with the same excitation energy, the isomeric-yield ratios of 89m,gNb in the 89Y(α, 4n) and 89Y(3He, 3n) reactions are higher than those in the 93Nb(γ, 4n) and natZr(p, xn) reactions, which indicates the role of input angular momentum. The isomeric-yield ratios of 89m,gNb in the 93Nb(γ, 4n), natZr(p, xn), 89Y(α, 4n), and 89Y(3He, 3n) reactions were also calculated theoretically using computer code TALYS 1.4. The theoretical isomeric-yield ratios of 89m,gNb from four reactions increase with excitation energy. However, the theoretical value are significantly higher than the experimental data in the 93Nb(γ, 4n) and natZr(p, xn) reactions but slightly lower or comparable in the 89Y(α, 4n) rand 89Y(3He, 3n) reactions.

Cumulative yields of short-lived ruthenium isotopes in the thermal neutron induced fission of233U,235U and239Pu

Cumulative yields of short-lived ruthenium isotopes in the thermal neutron induced fission of235U,235U and239Pu have been determined using a fast radiochemical separation technique followed by gamma spectrometry. The cumulative yields of107Ru and103Ru in233U (nth, f) and107Ru and109Ru in239Pu (nth, f) are determined for the first time. The measured cumulative yields are converted to chain yields assuming normal charge distribution systematics for comparison with the literature data on chain yields.

Independent isomeric yield ratios of 95m,gNb in the natMo(γ, pxn) and natZr(p, xn) reactions

The independent isomeric yield ratios of 95m,gNb from the natMo(γ, pxn) reactions with bremsstrahlung end-point energies of 45, 50, 55, 60, and 70xa0MeV were determined by an activation and an off-line γ-ray spectrometric technique at the Pohang accelerator laboratory (PAL), Korea. The isomeric yield ratios of 95m,gNb from the natZr(p, xn) reactions were also determined in eight different proton energies within 19.4–44.7xa0MeV by a stacked-foil activation and an off-line γ-ray spectrometric technique using the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences (KIRAMS), Korea. The measured isomeric yield ratios of 95m,gNb from the present work and the literature data in the natMo(γ, pxn) and natZr(p, xn) reactions were compared with the similar literature data in the natMo(p, αxn) reactions. It was found that the isomeric yield ratio of 95m,gNb increases with projectile energy, which indicate the effect of excitation energy. However, at the same excitation energy, the isomeric yield ratios of 95m,gNb in the natZr(p, xn) and natMo(p, αxn) reactions are higher than those in the natMo(γ, pxn) reaction, which indicates the role of input angular momentum. The isomeric yield ratios of 95m,gNb in the natMo(γ, pxn), natZr(p, xn), and natMo(p, αxn) reactions were also calculated using computer code TALYS 1.4. The calculated isomeric yield ratios of 95m,gNb from three reactions increase with excitation energy. However, in all the three reactions, the calculated values are significantly higher than the experimental data.

151Eu(n,γ)152m1Eu reaction cross-section measurement at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

The 151Eu(n,γ)152m1Eu reaction cross-section at the neutron energies (En) of 1.12, 2.12, 3.12 and 4.12xa0MeV was determined by using activation and off-line γ-ray spectrometric technique. The mono-energetic neutrons of 1.12–4.12xa0MeV were generated from the 7Li(p,n) reaction by using the proton beam energies of 3–6xa0MeV. The 197Au(n,γ)198Au reaction cross-section was used as the neutron flux monitor. The 151Eu(n,γ)152m1Eu reaction cross-section was also calculated by using computer code TALYS 1.6 and compared with the experimental data to check its validity. The Eu(n,γ) reaction cross-section is important for the safety of the fast reactor and conventional fission reactor.

Determination of 110Cd(n,γ)111mCd and 111Cd(n,n′)111mCd reaction cross-sections at the neutron energies of 1.12–4.12 MeV

The 110Cd(n,γ)111mCd and 111Cd(n,n′)111mCd reaction cross-sections at the neutron energies of 1.12, 2.12, 3.12 and 4.12xa0MeV were determined for the first time by using activation and off-line γ-ray spectrometric technique. The values from preset work and literature data at other neutron energies are compared with the theoretical values based on TALYS 1.6 and found to be in agreement. The formation cross-section of 111mCd from the (n,γ) and (n,n′) reaction of natCd is important for neutron economy and estimation of dose of the Cd control rod use in the reactor.

Measurement of 197Au(n,γ)198gAu reaction cross-section at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

Abstract The 197Au(n,u2009γ)198Au reaction cross-sections at the neutron energies of 1.12, 2.12, 3.12 and 4.12u2009MeV were determined by using activation and off-line γ-ray spectrometric technique. The mono-energetic neutron energies of 1.12–4.12u202fMeV were generated from the 7Li(p,u2009n) reaction by using the proton energies of 3 and 4u2009MeV from the folded tandem ion beam accelerator (FOTIA) at BARC as well as 5 and 6u2009MeV from the Pelletron facility at TIFR, Mumbai. The 115In(n,γ)116mIn reaction cross-section was used as the neutron flux monitor. The 197Au(n,u2009γ)198Au reaction cross-section at the neutron energies of 3.12 and 4.12u2009MeV are reported for the first time. The 197Au(n,u2009γ)198Au reaction cross-sections at 1.12 and 2.12u2009MeV are close to the literature data of in between neutron energies. The 197Au(n,u2009γ)198Au cross-section was also calculated theoretically by using the computer code TALYS 1.6 and found to be higher than the experimental data of present work and literature data within the neutron energies of 0.8 to 4u2009MeV.