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F P Hesberger - One of the best experts on this subject based on the ideXlab platform.
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Spontaneous Fission instability of the neutron deficient no and rf isotopes the new isotope no 249
Physical Review C, 2021Co-Authors: J Khuyagbaatar, F P Hesberger, B Kindler, H Brand, R A Cantemir, Ch E Dullmann, E Jager, J Krier, N Kurz, B LommelAbstract:In the heaviest elements, the instability of atomic nuclei against Spontaneous Fission leads to ever shorter nuclear half-lives. Upon falling below a timescale of ${10}^{\ensuremath{-}14}$ s, the border of existence of isotopes is crossed because this is the timescale on which the formation of atomic shells occurs. Analysis of the experimental data on the Spontaneous Fission half-lives of Rf isotopes in relation with their expected single-particle orbitals hint at a potentially abrupt decrease in half-lives of unknown neutron-deficient Rf isotopes with neutron numbers $l149$, which suggests that the isotopic border is already almost reached. However, this conjecture, which cannot be explained within the current knowledge, was directly related to uncertainty in the experimental data on $^{253}\mathrm{Rf}$. We revisited the decay of $^{253}\mathrm{Rf}$ and identified two Fission activities, which are attributed to decays of the two different states with half-lives of $12.{8}_{\ensuremath{-}3.4}^{+7.0}$ ms and ${44}_{\ensuremath{-}10}^{+17}\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{s}$. In addition, hitherto unknown $\ensuremath{\alpha}$ decay in $^{253}\mathrm{Rf}$, which is followed by $\ensuremath{\alpha}$ decay of the new isotope $^{249}\mathrm{No}$ with a half-life of ${15}_{\ensuremath{-}7}^{+74}$ ms, was observed. Based on our new data, no abrupt decreases in half-lives of the neutron-deficient No and Rf isotopes are expected, which is in line with theoretical predictions. Fission half-lives of the two different states in $^{253}\mathrm{Rf}$ are benchmark cases for the theoretical description of the single-particle orbital influence on the Fission process.
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k isomerism in 255 rf and total kinetic energy measurements for Spontaneous Fission of 255 256 258 rf
Physical Review C, 2020Co-Authors: P Mosat, F P Hesberger, D Ackermann, B Andel, S Antalic, M Block, S Hofmann, Z Kalaninova, B KindlerAbstract:Spontaneous Fission properties of the isotopes $^{255}\mathrm{Rf}$, $^{256}\mathrm{Rf}$, and $^{258}\mathrm{Rf}$ produced in the reactions $^{50}\mathrm{Ti}+^{207}\mathrm{Pb}$, $^{50}\mathrm{Ti}+^{208}\mathrm{Pb}$, and $^{50}\mathrm{Ti}+^{209}\mathrm{Bi}$ were studied. The method of time and position correlations was used to identify Spontaneous Fission events. The correction to the energy deficit in measured total kinetic energy (TKE) determined on the basis of a study of $^{252}\mathrm{No}$ was applied to evaluate the $\overline{\mathrm{TKE}}$ of investigated rutherfordium isotopes. A signature which we assigned tentatively to bimodal Fission was observed in TKE distributions of $^{255}\mathrm{Rf}$ and $^{256}\mathrm{Rf}$. Two new high-K isomeric states in $^{255}\mathrm{Rf}$ were identified by ER-CE-(CE)-$\ensuremath{\alpha}$/SF correlation search, with half-lives of ${38}_{\ensuremath{-}7}^{+12}$ and ${15}_{\ensuremath{-}4}^{+6}$ $\ensuremath{\mu}\mathrm{s}$ at excitation energies 1150--1450 and 900--1200 keV, respectively. Including those metastable states a tentative partial level scheme was proposed.
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Spontaneous Fission of rutherfordium isotopes total kinetic energies
Epj Web of Conferences, 2019Co-Authors: Pavol Mosat, F P Hesberger, D Ackermann, B Andel, S Antalic, M Block, S Hofmann, Zdenka Kalaninova, B KindlerAbstract:The isotopes 255,256,258 Rf were produced in the fusion-evaporation reactions 50 Ti + 207,208 Pb and 50 Ti + 209 Bi at GSI Darmstadt, using the velocity filter SHIP. Total kinetic energies of fragments from Spontaneous Fission for these isotopes were evaluated with a correction to pulse-height defect.
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total kinetic energy measurements for Spontaneous Fission of 255 256 258 rf
Acta Physica Polonica B, 2018Co-Authors: P Mosať, F P Hesberger, D Ackermann, B Andel, S Antalic, M Block, Zdenka Kalaninova, B Kindler, Stefan G Hofmann, I KojouharovAbstract:Spontaneous Fission of 255Rf, 256Rf and 258Rf was studied at SHIP in GSI Darmstadt. The isotopes were produced in fusion–evaporation reactions 50Ti + 207,208Pb and 50Ti + 209Bi (compound nuclei 257Rf, 258Rf and 259Db, respectively) and implanted into the focal plane detector of the SHIP setup. The deficit in the measured fragments energies was evaluated as a function of implantation depth of evaporation residues in the silicon detector. This correction was applied to obtain the mean total kinetic energies of 255Rf, 256Rf and 258Rf.
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Spontaneous Fission properties of superheavy elements
European Physical Journal A, 2017Co-Authors: F P HesbergerAbstract:Spontaneous Fission properties of transuranium isotopes are reviewed. Specific emphasis was laid on brief historical overviews of theoretical descriptions and experimental determination of basic properties as Spontaneous Fission half-lives, Fission barriers, or total kinetic energy release in Fission. Experimental Spontaneous Fission half-lives are compared with the results of recent theoretical predictions. Hindrance factors for Spontaneous Fission of odd-mass nuclei are discussed in context with the configuration (spin, parity) of the Fissioning states and the change in energy of single particle levels at deformation. Kinetic energy release and mass distributions are discussed in the context of different Fission modes, as symmetric and asymmetric or Fission from elongated or compact shapes of the nascent Fission fragments. An overview of recent Fission barrier calculations of superheavy elements on the basis of macroscopic-microscopic models or self-consistent calculations is given, and the results are compared for selected examples.
G M Terakopian - One of the best experts on this subject based on the ideXlab platform.
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structure of nd 155 and gd 163 from cf 252 Spontaneous Fission
Physical Review C, 2020Co-Authors: J M Eldridge, A V Ramayya, J H Hamilton, G M Terakopian, Yu Ts Oganessian, E H Wang, C J Zachary, B M Musangu, Y X Luo, J O RasmussenAbstract:Background: A puzzle has arisen recently caused by the apparent shift in maximum deformation from the expected $^{66}\mathrm{Dy}$ isotopic chain to the ${}_{60}\mathrm{Nd}$ isotopic chain in the $82lNl126$ and $50lZl82$ midshell region.Purpose: This work provides data for two specific nuclei with odd neutron numbers, $^{155}\mathrm{Nd}$ and $^{163}\mathrm{Gd}$, useful for constraining parameters in models that seek to answer the six proton shift in maximum deformation.Method: Data from the Spontaneous Fission of $^{252}\mathrm{Cf}$ were taken by the Gammasphere detector array at Lawrence Berkeley National Laboratory to observe the excited states of $^{155}\mathrm{Nd}$ and $^{163}\mathrm{Gd}$.Results: The structure of $^{163}\mathrm{Gd}$ has been expanded with the addition of two new levels and three new $\ensuremath{\gamma}$ rays, which are found to be consistent with previously published calculations and the structure of $^{165}\mathrm{Dy}$. In $^{155}\mathrm{Nd}$, nine new levels and 12 new $\ensuremath{\gamma}$ rays are observed. The spins and parities of the previously known levels in $^{155}\mathrm{Nd}$ have been reassigned from a $\ensuremath{\nu}3/{2}^{\ensuremath{-}}[521]$ ground state configuration to a $\ensuremath{\nu}5/{2}^{+}[642]$ isomeric configuration by comparison of these newly observed levels with levels in $^{153}\mathrm{Nd}$ and $^{155}\mathrm{Sm}$.Conclusion: Further experimentation is required to determine the energy of the newly reassigned $\ensuremath{\nu}5/{2}^{+}[642]$ level in $^{155}\mathrm{Nd}$ with respect to the suspected $\ensuremath{\nu}3/{2}^{\ensuremath{-}}[521]$ ground state. Additionally, more experiments should be conducted to further determine the structure of neutron rich nuclei, rarely produced in the Spontaneous Fission of $^{252}\mathrm{Cf}$, such as $^{163}\mathrm{Gd}$.
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searches for superheavy elements in nature cosmic ray nuclei Spontaneous Fission
Nuclear Physics, 2015Co-Authors: G M Terakopian, S N DmitrievAbstract:Abstract There is little chance that superheavy nuclei with lifetimes of no less than 100 million years are present on the stability island discovered at present. Also, pessimistic are the results of estimates made about their nucleosynthesis in r-process. Nevertheless, the search for these nuclei in nature is justified in view of the fundamental importance of this topic. The first statistically significant data set was obtained by the LDEF Ultra-Heavy Cosmic-Ray Experiment, consisting of 35 tracks of actinide nuclei in galactic cosmic rays. Because of their exceptionally long exposure time in Galaxy, olivine crystals extracted from meteorites generate interest as detectors providing unique data regarding the nuclear composition of ancient cosmic rays. The contemporary searches for superheavy elements in the earth matter rely on knowledge obtained from chemical studies of artificially synthesized superheavy nuclei. New results finding out the chemical behavior of superheavy elements should be employed to obtain samples enriched in their homologues. The detection of rare Spontaneous Fission events and the technique of accelerator mass spectrometry are employed in these experiments.
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observation of 10 be emission in the cold ternary Spontaneous Fission of 252 cf
Physical Review Letters, 1998Co-Authors: A V Ramayya, J H Hamilton, J K Hwang, A Sandulescu, A Florescu, G M Terakopian, A V DanielAbstract:The emission of {sup 10}Be in ternary cold neutronless Spontaneous Fission of {sup 252}Cf is observed with the Gammasphere consisting of 72 detectors. The {gamma} ray corresponding to the decay of the first 2{sup +} state in {sup 10}Be is observed in coincidence with the {gamma} rays of the Fission partners of {sup 96}Sr and {sup 146}Ba . The yield to the first excited state of {sup 10}Be in the {sup 96}Sr- {sup 146}Ba split is the order of 4.0{times}10{sup {minus}4} per 100 Fission events. {copyright} {ital 1998} {ital The American Physical Society}
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yields of correlated fragment pairs in Spontaneous Fission of 252 cf
Physical Review C, 1997Co-Authors: A V Ramayya, J H Hamilton, J Kormicki, G M Terakopian, Yu Ts Oganessian, G S Popeko, A V Daniel, B R S BabuAbstract:Independent yields of 139 individual secondary (appearing after neutron evaporation) fragment pairs of five different charge splits ${(Z}_{L}{/Z}_{H}=$46/52, 44/54, 42/56, 40/58, and 38/60) have been experimentally measured by detecting the coincidences between prompt $\ensuremath{\gamma}$ rays emitted in the Spontaneous Fission of ${}^{252}\mathrm{Cf}.$ Nuclear charge and mass distributions of Fission fragments that follow from the measured yields of individual fragment pairs are consistent with similar previously known more integral data. Another type of data extracted from the yields of fragment pairs is the multiplicity distributions of prompt neutrons emitted in the five above charge divisions of ${}^{252}$Cf. For the measured charge splits, about 70% of the Fission events where $g~7$ neutrons are evaporated from the Fission fragments occur for the Mo-Ba split of ${}^{252}$Cf. Mass and excitation energy distributions of primary Ru-Xe, Mo-Ba, and Zr-Ce fragments were deduced from a least squares fit to the yield pattern of secondary fragment pairs. For the Ru-Xe and Zr-Ce splits, the experimental data are well fitted by assuming one Fission mode with average total kinetic energy $〈\mathrm{TKE}〉$ values close to the value of $〈\mathrm{TKE}〉$ known for the ${}^{252}\mathrm{Cf}$ Spontaneous Fission. For the Mo-Ba split, a successful fit could be obtained only with the assumption that, in addition to this ``normal'' Fission mode, a second mode with a remarkably lower value of $〈\mathrm{TKE}〉$ of 153 MeV contributes to this charge split. This is 36 MeV lower than for the normal mode. These data indicate that in mode two the barium nuclei are hyperdeformed (3:1 axis ratio) at scission. Mean angular momentum values of Mo-Ba Fission fragments observed in pairs together with various partners have been deduced from the measured populations of different spin levels of the fragment nuclei. These angular momentum values are discussed in terms of their dependence on the primary fragment excitation energy and presence of two Fission modes.
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new Spontaneous Fission mode for 252cf indication of hyperdeformed 144 145 146ba at scission
Physical Review Letters, 1996Co-Authors: G M Terakopian, A V Ramayya, J H Hamilton, J Kormicki, B R S Babu, Yu Ts Oganessian, G S Popeko, A V Daniel, K Butlermoore, W CAbstract:From {gamma}-ray coincidence studies following Spontaneous Fission of {sup 252}Cf, direct measurements of yields and neutron multiplicities were made for Sr-Nd, Zr-Ce, Mo-Ba, Ru-Xe, and Pd-Te correlated pairs. A strong enhancement of the 7-10 neutron channels for Mo-Ba pairs is observed. A new Fission mode associated with the enhanced neutron yields is identified. These data can be interpreted in terms of one or more of {sup 144,145,146}Ba being hyperdeformed at scission. Mean field calculations predict a hyperdeformed third minimum in {sup 252}Cf and an extremely deformed {sup 146}Ba fragment at scission. {copyright} {ital 1996 The American Physical Society.}
Zhongzhou Ren - One of the best experts on this subject based on the ideXlab platform.
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predictions on properties of α decay and Spontaneous Fission in superheavy odd z nuclei
Physical Review C, 2014Co-Authors: Yibin Qian, Zhongzhou RenAbstract:We systematically investigate the competition between a decay and Spontaneous Fission in the region of superheavy odd-Z nuclei up to Z = 121. The heavier cluster emissions are somewhat of interest for these superheavy nuclei (SHN) as well. In detail, on the basis of the density-dependent cluster model, the deformed a-core potential is obtained from the double-folding integral. The a-decay half-lives of involved nuclei are then achieved within the improved two-potential approach. On the other hand, the Spontaneous Fission half-lives are given by the employed formula related to the fissility parameter and the Fission barrier height. It is interesting that the decay characteristic of studied nuclei is discussed with varying of the Z and N numbers to some extent, including the tentative detection on the "island of stability." The present results can be expected to be useful in the future experiment particularly for the unknown elements 119 and 121, namely the identification of synthesized SHN.
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competition between α decay and Spontaneous Fission for heavy and superheavy nuclei
Physical Review C, 2008Co-Authors: Zhongzhou Ren, Yanqing GuoAbstract:We systematically investigate the {alpha}-decay and Spontaneous Fission half-lives for heavy and superheavy nuclei with proton number Z{>=}90. The {alpha}-decay half-lives are obtained by the deformed version of the density-dependent cluster model (DDCM). In the DDCM, the microscopic potential between the {alpha} particle and the daughter nucleus is evaluated numerically from the double-folding model with the M3Y interaction. The influence of the core deformation on the double-folding potential is also properly taken into account by the multipole expansion method. The Spontaneous Fission half-lives of nuclei from {sup 232}Th to {sup 286}114 are calculated with the parabolic potential approximation by taking nuclear structure effects into account. The agreement between theoretical results and the newly observed data is satisfactory for both {alpha} emitters and Spontaneous Fission nuclei. The competition between {alpha} decay and Spontaneous Fission is analyzed in detail and the branching ratios of these two decay modes are predicted for the unknown cases.
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Spontaneous Fission half lives of heavy nuclei in ground state and in isomeric state
Nuclear Physics, 2005Co-Authors: Zhongzhou RenAbstract:Abstract We generalize the formulas of Spontaneous Fission half-lives of even–even nuclei in their ground state to both the case of odd nuclei and the case of Fission isomers [Phys. Rev. C 71 (2005) 014309]. The Spontaneous Fission half-lives of odd– A nuclei and of odd–odd nuclei in the ground state are calculated by Swiatecki's formula, by its generalized form, and by a new formula where the blocking effect of unpaired nucleon on the half-lives has been taken into account with different mechanisms. By introducing a blocking factor or a generalized seniority in the formulas of the half-lives of even–even nuclei, we can reasonably reproduce the experimental Fission half-lives of odd– A nuclei and of odd–odd nuclei with the same parameters used in ground state of even–even nuclei. For Spontaneous Fission of the isomers in transuranium nuclei the new formula can be simplified into a three-parameter formula and the isomeric half-lives can be well reproduced by the formula. The new formula of the isomeric half-lives is as good as Metag's formula of Fission isomers. The half-lives of isomers from these formulas are very accurate and therefore these formulas can give reliable predictions for half-lives of new isomers of neighboring nuclei.
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systematical law of Spontaneous Fission half lives of heavy nuclei
Physical Review C, 2005Co-Authors: Zhongzhou RenAbstract:Systematic calculations on Spontaneous Fission half-lives of heavy nuclei are carried out by Swiatecki's formula with new parameters and by its generalized form. A new formula with only four parameters is also proposed for Spontaneous Fission half-lives. Experimental half-lives are well reproduced by the three formulas. We have found from systematic analysis of available data that there is a long lifetime line of Spontaneous Fission $N=Z+52\phantom{\rule{0.3em}{0ex}}$ for heavy elements with $Z\ensuremath{\ge}90$. The new formula can be used to predict the Spontaneous Fission half-lives of heavy nuclei not far away from this long lifetime line. The small deviation between experimental half-lives and theoretical ones from the new formula is analyzed and discussed.
J H Hamilton - One of the best experts on this subject based on the ideXlab platform.
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structure of nd 155 and gd 163 from cf 252 Spontaneous Fission
Physical Review C, 2020Co-Authors: J M Eldridge, A V Ramayya, J H Hamilton, G M Terakopian, Yu Ts Oganessian, E H Wang, C J Zachary, B M Musangu, Y X Luo, J O RasmussenAbstract:Background: A puzzle has arisen recently caused by the apparent shift in maximum deformation from the expected $^{66}\mathrm{Dy}$ isotopic chain to the ${}_{60}\mathrm{Nd}$ isotopic chain in the $82lNl126$ and $50lZl82$ midshell region.Purpose: This work provides data for two specific nuclei with odd neutron numbers, $^{155}\mathrm{Nd}$ and $^{163}\mathrm{Gd}$, useful for constraining parameters in models that seek to answer the six proton shift in maximum deformation.Method: Data from the Spontaneous Fission of $^{252}\mathrm{Cf}$ were taken by the Gammasphere detector array at Lawrence Berkeley National Laboratory to observe the excited states of $^{155}\mathrm{Nd}$ and $^{163}\mathrm{Gd}$.Results: The structure of $^{163}\mathrm{Gd}$ has been expanded with the addition of two new levels and three new $\ensuremath{\gamma}$ rays, which are found to be consistent with previously published calculations and the structure of $^{165}\mathrm{Dy}$. In $^{155}\mathrm{Nd}$, nine new levels and 12 new $\ensuremath{\gamma}$ rays are observed. The spins and parities of the previously known levels in $^{155}\mathrm{Nd}$ have been reassigned from a $\ensuremath{\nu}3/{2}^{\ensuremath{-}}[521]$ ground state configuration to a $\ensuremath{\nu}5/{2}^{+}[642]$ isomeric configuration by comparison of these newly observed levels with levels in $^{153}\mathrm{Nd}$ and $^{155}\mathrm{Sm}$.Conclusion: Further experimentation is required to determine the energy of the newly reassigned $\ensuremath{\nu}5/{2}^{+}[642]$ level in $^{155}\mathrm{Nd}$ with respect to the suspected $\ensuremath{\nu}3/{2}^{\ensuremath{-}}[521]$ ground state. Additionally, more experiments should be conducted to further determine the structure of neutron rich nuclei, rarely produced in the Spontaneous Fission of $^{252}\mathrm{Cf}$, such as $^{163}\mathrm{Gd}$.
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nuclear structure studies of some neutron rich nuclei produced in 252cf Spontaneous Fission
Journal of Physics: Conference Series, 2015Co-Authors: A V Ramayya, J H Hamilton, J K HwangAbstract:High spin states of neutron-rich nuclei such as 133,134Te, 93Sr, 105Nb have been studied by measuring γ- γ- γ coincidences (cube), γ- γ- γ- γ coincidences (hypercube) and angular correlations from the Spontaneous Fission of 252Cf with the LBNL Gammasphere detector array. Four types of particle-hole bands built on the known 334.3 keV isomer in 133Te were identified. The level structure of 93Sr is interpreted, in part, as arising from the weak coupling of the 1d5/2 neutron hole to the yrast states of the 94Sr core. The g-factor of the 4+ state in 134Te was measured, for the first time, by using a new technique developed for measuring angular correlations with Gammasphere. A new level scheme of 105Nb was established. Three new collective bands were identified with a total of 14 new levels and 36 new γ transitions. In 117-122Cd, a shift to more slightly deformed structures was found where the excited levels do not fit the long held picture of one, two and three phonon bands.
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observation of 10 be emission in the cold ternary Spontaneous Fission of 252 cf
Physical Review Letters, 1998Co-Authors: A V Ramayya, J H Hamilton, J K Hwang, A Sandulescu, A Florescu, G M Terakopian, A V DanielAbstract:The emission of {sup 10}Be in ternary cold neutronless Spontaneous Fission of {sup 252}Cf is observed with the Gammasphere consisting of 72 detectors. The {gamma} ray corresponding to the decay of the first 2{sup +} state in {sup 10}Be is observed in coincidence with the {gamma} rays of the Fission partners of {sup 96}Sr and {sup 146}Ba . The yield to the first excited state of {sup 10}Be in the {sup 96}Sr- {sup 146}Ba split is the order of 4.0{times}10{sup {minus}4} per 100 Fission events. {copyright} {ital 1998} {ital The American Physical Society}
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cold binary and ternary fragmentations in Spontaneous Fission of252cf
Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields, 1997Co-Authors: A V Ramayya, J H Hamilton, J K Hwang, L K Peker, J Kormicki, B R S Babu, T N Ginter, A Sandulescu, A FlorescuAbstract:The phenomenon of cold (neutronless) binary and ternary Fission in Spontaneous Fission of252 Cf was experimentally observed by triple gamma coincidence technique with Gammasphere with 72 gamma-ray detectors. Many correlated pairs for both binary and ternary (4He,10Be) Fission were observed in the Spontaneous Fission of252 Cf. Yields of cold ternary and cold binary Fission were extracted. These results are compared with the theoretical calculations using M3Y nucleon-nucleon potential and WKB approximation for barrier penetration.
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yields of correlated fragment pairs in Spontaneous Fission of 252 cf
Physical Review C, 1997Co-Authors: A V Ramayya, J H Hamilton, J Kormicki, G M Terakopian, Yu Ts Oganessian, G S Popeko, A V Daniel, B R S BabuAbstract:Independent yields of 139 individual secondary (appearing after neutron evaporation) fragment pairs of five different charge splits ${(Z}_{L}{/Z}_{H}=$46/52, 44/54, 42/56, 40/58, and 38/60) have been experimentally measured by detecting the coincidences between prompt $\ensuremath{\gamma}$ rays emitted in the Spontaneous Fission of ${}^{252}\mathrm{Cf}.$ Nuclear charge and mass distributions of Fission fragments that follow from the measured yields of individual fragment pairs are consistent with similar previously known more integral data. Another type of data extracted from the yields of fragment pairs is the multiplicity distributions of prompt neutrons emitted in the five above charge divisions of ${}^{252}$Cf. For the measured charge splits, about 70% of the Fission events where $g~7$ neutrons are evaporated from the Fission fragments occur for the Mo-Ba split of ${}^{252}$Cf. Mass and excitation energy distributions of primary Ru-Xe, Mo-Ba, and Zr-Ce fragments were deduced from a least squares fit to the yield pattern of secondary fragment pairs. For the Ru-Xe and Zr-Ce splits, the experimental data are well fitted by assuming one Fission mode with average total kinetic energy $〈\mathrm{TKE}〉$ values close to the value of $〈\mathrm{TKE}〉$ known for the ${}^{252}\mathrm{Cf}$ Spontaneous Fission. For the Mo-Ba split, a successful fit could be obtained only with the assumption that, in addition to this ``normal'' Fission mode, a second mode with a remarkably lower value of $〈\mathrm{TKE}〉$ of 153 MeV contributes to this charge split. This is 36 MeV lower than for the normal mode. These data indicate that in mode two the barium nuclei are hyperdeformed (3:1 axis ratio) at scission. Mean angular momentum values of Mo-Ba Fission fragments observed in pairs together with various partners have been deduced from the measured populations of different spin levels of the fragment nuclei. These angular momentum values are discussed in terms of their dependence on the primary fragment excitation energy and presence of two Fission modes.
A Sandulescu - One of the best experts on this subject based on the ideXlab platform.
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Spontaneous Fission cluster emission and alpha decay of 222ra in a unified description
Annals of Physics, 2017Co-Authors: M Mirea, R Budaca, A SandulescuAbstract:Abstract Three disintegration modes of the parent nucleus 222 Ra , namely the Fission, the cluster emission and the alpha decay, are treated in a unified manner. The half-lives are calculated by taking into account the penetration probabilities through the potential barrier along disintegration trajectories in the deformation space appropriate to each kind of decay. These trajectories start from the same parent ground state configuration. The disintegration paths are obtained from the least action principle. The deformation energy is calculated within the macroscopic–microscopic procedure based on the Woods–Saxon two center shell model. The effective mass is determined microscopically with the cranking method and the Gaussian Overlap Approximation. The nuclear shape parametrization is characterized by the most important five degrees of freedom encountered in Fission, corresponding to the elongation, the mass asymmetry, the necking and the two fragment deformations. Partial half-life results for alpha-decay and cluster emission processes treated as superasymmetric Fission agree with the experimental data. The Spontaneous Fission half-life is predicted. Molecular states are evidenced for the superasymmetric Fission process as a result of the large shell effects in the nascent fragments.
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observation of 10 be emission in the cold ternary Spontaneous Fission of 252 cf
Physical Review Letters, 1998Co-Authors: A V Ramayya, J H Hamilton, J K Hwang, A Sandulescu, A Florescu, G M Terakopian, A V DanielAbstract:The emission of {sup 10}Be in ternary cold neutronless Spontaneous Fission of {sup 252}Cf is observed with the Gammasphere consisting of 72 detectors. The {gamma} ray corresponding to the decay of the first 2{sup +} state in {sup 10}Be is observed in coincidence with the {gamma} rays of the Fission partners of {sup 96}Sr and {sup 146}Ba . The yield to the first excited state of {sup 10}Be in the {sup 96}Sr- {sup 146}Ba split is the order of 4.0{times}10{sup {minus}4} per 100 Fission events. {copyright} {ital 1998} {ital The American Physical Society}
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cold binary and ternary fragmentations in Spontaneous Fission of252cf
Nuovo Cimento Della Societa Italiana Di Fisica A-nuclei Particles and Fields, 1997Co-Authors: A V Ramayya, J H Hamilton, J K Hwang, L K Peker, J Kormicki, B R S Babu, T N Ginter, A Sandulescu, A FlorescuAbstract:The phenomenon of cold (neutronless) binary and ternary Fission in Spontaneous Fission of252 Cf was experimentally observed by triple gamma coincidence technique with Gammasphere with 72 gamma-ray detectors. Many correlated pairs for both binary and ternary (4He,10Be) Fission were observed in the Spontaneous Fission of252 Cf. Yields of cold ternary and cold binary Fission were extracted. These results are compared with the theoretical calculations using M3Y nucleon-nucleon potential and WKB approximation for barrier penetration.
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zero neutron emission in Spontaneous Fission of 252cf a form of cluster radioactivity
Journal of Physics G, 1994Co-Authors: J H Hamilton, A V Ramayya, J Kormicki, A Sandulescu, W C, D Shi, J K Deng, S J Zhu, W Greiner, G M Ter AkopianAbstract:By using the triple gamma coincidence technique with 20 Ge detectors at the Holifield Laboratory in the Spontaneous Fission of 252Cf, neutronless fragmentations, like 104Mo-148Ba, 106Mo-146Ba, 108Mo-144Ba and 104Zr-148Ce, are experimentally observed directly for the first time. When zero neutron emission Spontaneous Fission occurs, essentially all the available energy goes into the total kinetic energy of the fragments (cold Fission). This process is seen theoretically to be an extension of cluster radioactivity, which involves the emission of one light fragment like 14C, 20O, (24)Ne or 28Mg to nearly equal fragments. In the neutronless Spontaneous Fission reported here, double fine structures (i.e. decays to the excited states of both fragments) are observed experimentally in contrast to fine structure in only the heavy partner populated by the light partner in earlier cluster radioactivity work. Neutronless Spontaneous Fission is discussed in the framework of cluster radioactivity.