Systematic decay analysis of 202Po∗ compound nucleus using Dynamical Cluster-decay Model

2019 ◽  
Vol 28 (12) ◽  
pp. 1950105 ◽  
Author(s):  
Pooja Kaushal ◽  
Manoj K. Sharma
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Degrees Of Freedom ◽  
Cluster Decay ◽  
Channel Cross Section ◽  
Decay Model ◽  
Cross Section Formula ◽  
Collective Clusterization ◽  
Mechanical Fragmentation

The decay analysis of [Formula: see text]Po[Formula: see text] compound nucleus (CN), formed via [Formula: see text]Ca+[Formula: see text]Gd reaction, with inclusion of additional degrees-of-freedom, i.e., the higher multipole deformations, the octupole ([Formula: see text]) and hexadecupole ([Formula: see text]), the corresponding “compact” orientations ([Formula: see text]), and noncoplanarity degree-of-freedom ([Formula: see text]0), is investigated within the collective clusterization approach. The Quantum Mechanical Fragmentation Theory (QMFT)-based Dynamical Cluster-decay Model (DCM), wherein the point of penetration [Formula: see text], fixed via the in-built neck-length parameter [Formula: see text] in [Formula: see text] (equivalently, the “barrier lowering” [Formula: see text]), is used to best fit the channel cross-section ([Formula: see text]) and predict the quasi-fission (qf)-like nCN cross-section [Formula: see text], if any, and the fusion–fission ([Formula: see text]) cross-sections. We also look for other target-projectile (t-p) combinations for the synthesis of CN [Formula: see text]Po[Formula: see text].

ENTRANCE-CHANNEL EFFECTS IN THE DYNAMICAL CLUSTER-DECAY MODEL FOR THE DECAY OF HOT AND ROTATING COMPOUND NUCLEUS 48Cr AT ${\rm E}_{CN}^{*}\approx 60\, {\rm MeV}$

2006 ◽  
Vol 15 (03) ◽  
pp. 699-717 ◽  
Author(s):  
BIRBIKRAM SINGH ◽  
MANOJ K. SHARMA ◽  
RAJ K. GUPTA ◽  
WALTER GREINER
Keyword(s):  
Compound Nucleus ◽  
Cross Sections ◽  
Entrance Channel ◽  
Cluster Decay ◽  
Intermediate Mass ◽  
Excitation Energies ◽  
Decay Model ◽  
Independence Hypothesis ◽  
Channel Effects ◽  
Collective Clusterization

The entrance-channel effects in the decay of hot and rotating compound nucleus 48 Cr *, formed in symmetric 24 Mg +24 Mg and asymmetric 36 Ar +12 C reactions, are studied as collective clusterization process, for emissions of both the light particles (LPs) as well as the intermediate mass fragments (IMFs), with in the dynamical cluster-decay model (DCM). We find that the little differences observed in the decay of equilibrated compound nucleus 48 Cr *, formed in the two entrance channels with about the same excitation energy, are not in variance with the Bohr's independence hypothesis. In other words, the present study confirms the entrance-channel independence of the decay of compound nucleus 48 Cr * formed due to different target-projectile combinations with similar excitation energies. The collective clusterization process is shown to contain the complete structure of the measured fragment cross sections as well as average total kinetic energies.

RESONANT SCATTERING OF SLOW NEUTRONS

1953 ◽  
Vol 31 (3) ◽  
pp. 432-452 ◽  
Author(s):  
B. N. Brockhouse
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Compound Nucleus ◽  
Neutron Energy ◽  
Cross Sections ◽  
Resonant Scattering ◽  
Scattering Cross Section ◽  
Scattering Cross ◽  
Cross Section Formula ◽  
Slow Neutrons

A method is described for measurement, as a function of neutron energy, of the scattering cross section for slow neutrons of materials having high absorption. The necessary corrections are discussed. The results are normalized to a vanadium scattering cross section of 5.07 barns inferred from the measured total cross section, [Formula: see text]. Measurements are presented for the low energy neutron resonances in cadmium, samarium, gadolinium, dysprosium, europium, rhodium, and indium. The single level Breit-Wigner formula is accurately obeyed for cadmium and samarium but not for gadolinium in which two resonances contribute. The scattering results indicate that the absorption cross sections of cadmium and samarium at resonance are higher than the values previously accepted. This has been confirmed by total cross section measurements on cadmium for which the Breit-Wigner parameters are E0 = 0.180 (±.003) ev., Γ = 0.113 ev., σa0 = 7750 barns, σP = 4.7 barns, aR = 7 × 10−3 cm. The spin of the compound nucleus is unity. For Sm149 the spin of the compound nucleus (0.096 ev. resonance) is [Formula: see text]. The scattering cross section of europium for neutrons of energy 0.03 ev. to 0.15 ev. is 8 barns, almost independent of the energy. The scattering cross section of dysprosium is 100 barns at 0.03 ev. and decreases slowly with increasing energy, thus confirming the existence of a level at negative neutron energy. The spin of the compound nucleus for the 1.26 ev. resonance in Rh103 is found to be unity and that for the 1.45 ev. resonance in In115 is found to be four.

scholarly journals Role of Polar vs Non-polar Configurations in the Decay of 268Sg* Compound Nucleus Within the Skyrme Energy Density Formalism

2021 ◽  
Vol 9 (1) ◽  
pp. 61-66
Author(s):  
Rajni Mittal ◽  
Kirandeep Sandhu ◽  
M. K. Sharma
Keyword(s):  
Experimental Data ◽  
Energy Density ◽  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Fission Cross Section ◽  
Cluster Decay ◽  
The Impact ◽  
Adequate Agreement

The effect of polar and non-polar configurations is investigated in the decay of 268Sg* compound nucleus formed via spherical projectile (30Si) and prolate deformed target (238U) using the dynamical cluster decay model. The SSK and GSkI skyrme forces are used to investigate the impact of polar and nonpolar (equatorial) configurations on the preformation probability P0 and consequently on the fission cross-sections of 268Sg* nucleus. For non-polar configuration some secondary peaks corresponding to magic shells Z=28 and N=50 are observed, whose magnitude is significantly suppressed for the polar counterpart. The effect of polar and non-polar configurations is further analyzed in reference to barrier lowering parameter ΔVB. The calculated fission cross-section find adequate agreement with experimental data for chosen set of skyrme forces.

DECAY OF 202Pb* FORMED IN 48Ca+154Sm REACTION USING THE DYNAMICAL CLUSTER-DECAY MODEL

2009 ◽  
Vol 18 (07) ◽  
pp. 1453-1467 ◽  
Author(s):  
SHEFALI KANWAR ◽  
MANOJ K. SHARMA ◽  
BIRBIKRAM SINGH ◽  
RAJ K. GUPTA ◽  
WALTER GREINER
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Fission Cross Section ◽  
Evaporation Residue ◽  
Entrance Channel ◽  
Cluster Decay ◽  
Excitation Energies ◽  
Shell Effects ◽  
Decay Model ◽  
Symmetric Fission

The decay of compound nucleus 202 Pb *, formed in entrance channel reaction 48 Ca +154 Sm at different incident energies, is studied by using the dynamical cluster-decay model (DCM) where all decay products are calculated as emissions of preformed clusters through the interaction barriers. The calculated results show an excellent agreement with experimental data for the fusion-evaporation residue cross-section σ ER together with the fusion-fission cross-section σ FF (taken as a sum of the energetically favored symmetric [Formula: see text] and near symmetric A=65–75 plus complementary fragments), and the competing, non-compound-nucleus quasi-fission cross-section σ QF where the entrance channel is considered not to loose its identity (and hence with preformation factor P0=1). The interesting feature of this study is that the three decay processes (ER, FF and QF) are quite comparable at low energies, ER being the most dominant, whereas at higher energies FF becomes most probable followed by ER and QF. The prediction of two fission windows, the symmetric fission (SF) and the near symmetric fission (nSF) whose contribution is more at lower incident energies, suggests the presence of a fine structure effect in the fusion-fission of 202 Pb *. This result is attributed to the shell effects (magic shells) playing effective role in the fragment preformation yields for 48 Ca +154 Sm reaction at lower excitation energies, giving rise to "shoulders", to an otherwise Gaussian FF mass distribution, responsible for the QF process. As a further verification of this result, absence of "shoulders" (hence, the QF component) in the decay of 192 Pb * due to 48 Ca +144 Sm reaction is also shown to be given by the calculations, in agreement with experiments. The only parameter of the model is the neck-length ΔR which shows that the ER occurs first, having the largest values of ΔR, and the FF and QF processes occur almost simultaneously at lower incident energies but the FF takes over QF at higher incident energies. In other words, the three processes occur in different time scales, QF competing with FF at lower incident energies.

scholarly journals Testing Compound Nucleus Hypothesis Across the 17O Nucleus Excitation

2019 ◽  
Vol 211 ◽  
pp. 02001 ◽  
Author(s):  
Aloys Nizigama ◽  
Pierre Tamagno ◽  
Olivier Bouland
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Center Of Mass ◽  
Ground States ◽  
Mass System ◽  
Resonance Parameters ◽  
Second Stage ◽  
Reference Framework ◽  
Kinetic Transformation

The excited compound nucleus 17O* has been studied over (n,α) and (α,n) cross sections modelling, respectively for 16O and 13C targets in their ground states. The modelling is fulfilled within the Reich-Moore formalism. We were able to calculate the (α,n) cross section by two separate ways: the direct kinematic standard route and by inversion of the (n,α) cross section using the compound nucleus hypothesis. Resonance parameters of the resolved resonance range (0 to 6 MeV) were borrowed from the CIELO project. In a first stage, the modelling is carried out in the referential of the incident particle (either way neutron or α) requesting conversion of the CIELO neutron-type resonance parameters to the α-type. In a second stage, the implementation is uniquely designed in the center of mass system of the excited compound nucleus. The resonance parameters are thus converted in that unique reference framework. The present investigation shows the consistency of the kinetic transformation that relies on the compound nucleus hypothesis.

MEASURING CAPTURE CROSS SECTIONS FOR HEAVY-ELEMENT PRODUCTION

2004 ◽  
Vol 13 (01) ◽  
pp. 293-300
Author(s):  
NEIL ROWLEY ◽  
NABILA GRAR
Keyword(s):  
Cross Section ◽  
Compound Nucleus ◽  
Cross Sections ◽  
Reaction Path ◽  
Superheavy Element ◽  
Evaporation Residue ◽  
Capture Cross ◽  
Total Capture ◽  
Capture Cross Sections

The creation of the nucleus of a superheavy element follows an extremely complex reaction path starting with the crossing of an external potential barrier (or distribution of barriers). This is followed by the evolution towards an equilibrated compound nucleus, which takes place in competition with pre-compound-nucleus fission (quasi-fission). Once formed the equilibrated compound nucleus must still survive against true fusion to yield a relatively long-lived evaporation residue. Much of this path is poorly understood, though recently, progress has been made on the role of the entrance-channel in quasi-fission. This will be briefly reported and a method proposed to measure the total capture cross section for such systems directly.

scholarly journals High-Throughput Particle Concentration Using Complex Cross-Section Microchannels

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 440 ◽  
Author(s):  
Asma Mihandoust ◽  
Sajad Razavi Bazaz ◽  
Nahid Maleki-Jirsaraei ◽  
Majid Alizadeh ◽  
Robert A. Taylor ◽  
...  
Keyword(s):  
Cross Section ◽  
High Throughput ◽  
Cross Sections ◽  
Particle Concentration ◽  
Separation Efficiency ◽  
Channel Cross Section ◽  
Total Width ◽  
Particle Focusing ◽  
Complex Cross ◽  
Complex Cross Section

High throughput particle/cell concentration is crucial for a wide variety of biomedical, clinical, and environmental applications. In this work, we have proposed a passive spiral microfluidic concentrator with a complex cross-sectional shape, i.e., a combination of rectangle and trapezoid, for high separation efficiency and a confinement ratio less than 0.07. Particle focusing in our microfluidic system was observed in a single, tight focusing line, in which higher particle concentration is possible, as compared with simple rectangular or trapezoidal cross-sections with similar flow area. The sharper focusing stems from the confinement of Dean vortices in the trapezoidal region of the complex cross-section. To quantify this effect, we introduce a new parameter, complex focusing number or CFN, which is indicative of the enhancement of inertial focusing of particles in these channels. Three spiral microchannels with various widths of 400 µm, 500 µm, and 600 µm, with the corresponding CFNs of 4.3, 4.5, and 6, respectively, were used. The device with the total width of 600 µm was shown to have a separation efficiency of ~98%, and by recirculating, the output concentration of the sample was 500 times higher than the initial input. Finally, the investigation of results showed that the magnitude of CFN relies entirely on the microchannel geometry, and it is independent of the overall width of the channel cross-section. We envision that this concept of particle focusing through complex cross-sections will prove useful in paving the way towards more efficient inertial microfluidic devices.

Dynamics of 16,18O-induced reactions using Ni, Ge and Mo targets

2016 ◽  
Vol 25 (11) ◽  
pp. 1650091 ◽  
Author(s):  
Rajni ◽  
Gurvinder Kaur ◽  
Manoj K. Sharma
Keyword(s):  
Cross Sections ◽  
Fusion Cross Section ◽  
Cluster Decay ◽  
Cross Section Data ◽  
Orientation Degree ◽  
Decay Modes ◽  
Section Data ◽  
Collective Clusterization ◽  
Good Agreement

Dynamical cluster decay model (DCM) based on the collective clusterization approach is employed to explore the dynamics of various even-mass Zr isotopes formed in [Formula: see text]O-induced reactions. In reference to the measured fusion cross-section data, various decay modes contributing towards [Formula: see text]Zr[Formula: see text] nuclei are investigated. Also, the role of deformations and orientation degree of freedom is analyzed by comparing results with spherical choice of fragmentation. In addition to this, the effect of entrance channel is explored for [Formula: see text]Zr[Formula: see text] and [Formula: see text]Kr[Formula: see text] nuclei formed in [Formula: see text]O and [Formula: see text]O-induced reactions. Besides this, the dynamics of relatively heavier mass Sn isotopes is exercised using [Formula: see text]O and [Formula: see text]O projectiles. The DCM calculated decay cross-sections find good agreement with available experimental data.

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