Fission of 180,182,183Hg and 178Pt nuclei at intermediate excitation energies

Purpose: The study of asymmetric and symmetric fission of 180,182,183Hg and 178Pt nuclei as a function of their excitation energy and isospin. Methods: Mass-energy distributions of fission fragments of 180Hg, 178Pt (two protons less than 180Hg), and 182Hg (two neutrons more than 180Hg) formed in the 36Ar+144Sm,142Nd, and 40Ca+142Nd reactions were measured at energies near and above the Coulomb barrier. Fission of 183Hg obtained in the reaction of 40Ca with 143Nd was also investigated to see if one extra neutron could lead to dramatic changes in the fission process due to the shape-staggering effect in radii, known in 183Hg. The measurements were performed with the double-arm time-of-flight spectrometer CORSET. Results: The observed peculiarities in the fission fragment mass-energy distributions for all studied nuclei may be explained by the presence of a symmetric fission mode and three asymmetric fission modes, manifested by the different total kinetic energies and fragment mass splits. The yield of symmetric mode grows with increasing excitation energy of compound nucleus. Conclusions: The investigated properties of asymmetric fission of 180,182,183Hg and 178Pt nuclei point out the existence of well-deformed proton shell at Z≈36 and a less deformed proton shell at Z ≈ 46.peerReviewe

Asymmetric and symmetric fission of excited nuclei of 180,190Hg and 184,192,202Pb formed in the reactions with 36Ar and 40,48Ca ions

Background: Observation of asymmetric fission of 180Hg has led to intensive theoretical and experimental studies of fission of neutron-deficient nuclei in the lead region. Purpose: The study of asymmetric and symmetric fission modes of 180,190Hg and 184,192,202Pb nuclei. Methods: Mass-energy distributions of fission fragments of 180,190Hg and 184Pb formed in the 36Ar+144,154Sm and 40Ca+144Sm reactions, respectively, at energies near the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET and compared with previously measured 192,202Pb isotopes produced in the 48Ca+144,154Sm reactions. The mass distributions for 180,190Hg and 184,192,202Pb together with old data for 187Ir, 195Au, 198Hg, 201Tl, 205,207Bi, 210Po, and 213At [J. Nucl. Phys. 53, 1225 (1991)] have been decomposed into symmetric and asymmetric fission modes. The total kinetic-energy distributions for different fission fragment mass regions have been analyzed for 180,190Hg and 184Pb. Results: The stabilization role of proton numbers at Z≈36, 38, Z≈45, 46, and Z=28/50 in asymmetric fission of excited preactinide nuclei has been observed. The high (≈145−MeV) and the low (≈128−MeV) energy components have been found in the total kinetic-energy distributions of 180,190Hg fission fragments corresponding to the fragments with proton numbers near Z≈46 and Z≈36, respectively. In the case of fission of 184Pb only the low-energy component (≈135MeV) for the fragments with masses corresponding to the proton numbers Z≈36 and 46 has been found. Conclusions: The studied properties of asymmetric fission of 180,190Hg and 184,192,202Pb nuclei point out the existence of well deformed proton shell at Z≈36 and less deformed proton shell at Z≈46.peerReviewe

Prospects for extra-short-duration pigeonpea in Northern Telangana zone of Andhra Pradesh, India.

To identify alternative rainy season crops that fit into the production zone of Northern Telangana, 11 lines of extra-short duration pigeonpeas (ESDP) [Cajanus cajan] which mature in 110-120 days were evaluated at research stations and farmers' fields during 1990-93. Yields ranged from 1.4 to 1.7 t/ha for the lines ICPL85010, ICPL88034 and ICPL84031. A further trial of ICPL85010 and other local crops confirmed that ESDP were the most profitable rainy season crop, and that they fitted into existing cropping systems and avoided Helicoverpa armigera infestation. Prolonged drought during flowering and pod development, pre-harvest sprouting and damage caused by Maruca testulalis [Maruca vitrata] may provide constraints to their adoption

Fission of Hg-180,Hg-182,Hg-183* and Pt-178* nuclei at intermediate excitation energies

Background: The nature of asymmetric fission of preactinides is not yet understood in detail, despite intense experimental and theoretical studies carried out at present. Purpose: The study of asymmetric and symmetric fission of Hg180,182,183 and Pt178 nuclei as a function of their excitation energy and isospin. Methods: Mass-energy distributions of fission fragments of Hg180, Pt178 (two protons less than Hg180), and Hg182 (two neutrons more than Hg180) formed in the Ar36+Sm144, Nd142, and Ca40+Nd142 reactions were measured at energies near and above the Coulomb barrier. Fission of Hg183 obtained in the reaction of Ca40 with Nd143 was also investigated to see if one extra neutron could lead to dramatic changes in the fission process due to the shape-staggering effect in radii, known in Hg183. The measurements were performed with the double-arm time-of-flight spectrometer CORSET. Results: The observed peculiarities in the fission fragment mass-energy distributions for all studied nuclei may be explained by the presence of a symmetric fission mode and three asymmetric fission modes, manifested by the different total kinetic energies and fragment mass splits. The yield of symmetric mode grows with increasing excitation energy of compound nucleus. Conclusions: The investigated properties of asymmetric fission of Hg180,182,183 and Pt178 nuclei point out the existence of well-deformed proton shell at Z≈36 and a less deformed proton shell at Z ≈ 46

Study of Binary Processes in the Reactions of 36Ar + 144, 154Sm and 68Zn + 112Sn Leading to the Formation of Neutron-Deficient Compound 180, 190Hg Nuclei

Abstract: A study is performed of the asymmetric fission of neutron-deficient mercury 180, 190Hg isotopes obtained in the reactions of 36Ar + 144, 154Sm and 68Zn + 112Sn at incident energies near and above the Coulomb barrier. The relative contributions from asymmetric and symmetric fission change along with the excitation energy of the fissile compound nucleus. The effect the characteristics of the entrance channel have on the dynamics of the reaction is studied

Investigation on Competing Fission Modes in 178Pt* Produced by 36Ar + 142Nd Reaction up to High Excitation Energies

Abstract: The mass–energy distributions of binary fission fragments (FFs) of excited exotic nucleus 178Pt* were measured via the fusion reaction 36Ar + 142Nd at different beam energies within 158–222 MeV range using the double arm time-of-flight spectrometer CORSET. The analysis of mass–energy matrices reveals the presence of both asymmetric and symmetric modes corresponding to respective lower and higher total kinetic energy (TKE) of the fragments within 42–64 MeV excitation energy. The agreement of measured mass width with theoretical systematics and dominance of the associated symmetric TKE component at 93 MeV excitation energy indicates the significant predominance/suppression of symmetric/asymmetric mode, respectively. The most probable light and heavy mass peaks of asymmetric fission mode of 178Pt are spotted at 79 and 99 u, respectively. As inferred from the theory, the mass–TKE events observed at the highest measured excitation energy (93 MeV) endorse the presence of the fast-fission process in 178Pt* at high angular momentum

Asymmetric and symmetric fission of excited nuclei of Hg 180,190 and Pb 184,192,202 formed in the reactions with Ar 36 and Ca 40,48 ions

Background: Observation of asymmetric fission of Hg180 has led to intensive theoretical and experimental studies of fission of neutron-deficient nuclei in the lead region. Purpose: The study of asymmetric and symmetric fission modes of Hg180,190 and Pb184,192,202 nuclei. Methods: Mass-energy distributions of fission fragments of Hg180,190 and Pb184 formed in the Ar36+Sm144,154 and Ca40+Sm144 reactions, respectively, at energies near the Coulomb barrier have been measured using the double-arm time-of-flight spectrometer CORSET and compared with previously measured Pb192,202 isotopes produced in the Ca48+Sm144,154 reactions. The mass distributions for Hg180,190 and Pb184,192,202 together with old data for Ir187, Au195, Hg198, Tl201, Bi205,207, Po210, and At213 [J. Nucl. Phys. 53, 1225 (1991)] have been decomposed into symmetric and asymmetric fission modes. The total kinetic-energy distributions for different fission fragment mass regions have been analyzed for Hg180,190 and Pb184. Results: The stabilization role of proton numbers at Z≈36, 38, Z≈45, 46, and Z=28/50 in asymmetric fission of excited preactinide nuclei has been observed. The high (≈145-MeV) and the low (≈128-MeV) energy components have been found in the total kinetic-energy distributions of Hg180,190 fission fragments corresponding to the fragments with proton numbers near Z≈46 and Z≈36, respectively. In the case of fission of Pb184 only the low-energy component (≈135MeV) for the fragments with masses corresponding to the proton numbers Z≈36 and 46 has been found. Conclusions: The studied properties of asymmetric fission of Hg180,190 and Pb184,192,202 nuclei point out the existence of well deformed proton shell at Z≈36 and less deformed proton shell at Z≈46

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Not AvailableBacterial blight (BB) and fungal blast diseases are the major biotic constraints that limit rice productivity. To sustain yield improvement in rice, it is necessary to developed yield potential of the rice varieties by incorporation of biotic stress resistance genes. Tellahamsa is a well-adapted popular high yielding rice variety in Telangana state, India. However, the variety is highly susceptible to BB and blast. In this study, simultaneous stepwise transfer of genes through marker-assisted backcross breeding (MABB) strategy was used to introgress two major BB (Xa21 and xa13) and two major blast resistance genes (Pi54 and Pi1) into Tellahamsa. In each generation (from F1 to ICF3) foreground selection was done using gene-specific markers viz., pTA248 (Xa21), xa13prom (xa13), Pi54MAS (Pi54) and RM224 (Pi1). Two independent BC2F1 lines of Tellahamsa/ISM (Cross-I) and Tellahamsa/NLR145 (Cross-II) possessing 92% and 94% recurrent parent genome (RPG) respectively were intercrossed to develop ICF1—ICF3 generations. These gene pyramided lines were evaluated for key agro-morphological traits, quality, and resistance against blast at three different hotspot locations as well as BB at two locations. Two ICF3 gene pyramided lines viz., TH-625-159 and TH-625-491 possessing four genes exhibited a high level of resistance to BB and blast. In the future, these improved Tellahamsa lines could be developed as mega varieties for different agro-climatic zones and also as potential donors for different pre-breeding rice research.Department of Biotechnology, Government of India grant # BT/ PR11705/AGR/02/646/200

Formation and Decay of the Composite System Z=120Z = 120 in Reactions with Heavy Ions at Energies Near the Coulomb Barrier

International audienceThe mass, energy and angular distributions of binary fragments formed in the reactions $^{64}$Ni + $^{238}$U, $^{58}$Fe + $^{244}$Pu, $^{52}$Cr + $^{248}$Cm, $^{54}$Cr + $^{248}$Cm at energies near the Coulomb barrier have been measured. The analysis of energy distributions of the symmetric fragments with mass numbers ${{{{A}_{{{\text{CN}}}}}} \mathord{\left/ {\vphantom {{{{A}_{{{\text{CN}}}}}} 2}} \right. \kern-0em} 2} \pm 20$

Investigating Mass–Energy Distributions of Fragments Produced in the 32S + 232Th → 264Sg Reaction at Energies Below and Near the Coulomb Barrier

Abstract: The mass-energy distributions of fragments of the reaction 32S + 232Th leading to the formation of 264Sg (Z = 106) at energies of incident ions 32S of 165, 181 and 200 MeV are measured. The contribution from the quasifission process is found at energies below and above the Coulomb barrier in the region of symmetric masses (АCN/2 ± 20). A high-energy symmetric fission mode is found at an energy of 165 MeV, which corresponds to the excitation energy of the compound 264Sg nucleus 45 MeV