EXCITATION FUNCTIONS OF α-INDUCED REACTIONS IN COBALT AND PRE-EQUILIBRIUM EFFECTS

2004 ◽  
Vol 13 (03) ◽  
pp. 585-595 ◽  
Author(s):  
M. AFZAL ANSARI ◽  
MOUNER A. Abd. ALSLAM ◽  
N. P. M. SATHIK ◽  
M. ISMAIL ◽  
M. H. RASHID
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Theoretical Calculations ◽  
Particle Energy ◽  
Activation Technique ◽  
Thermodynamical Equilibrium ◽  
Excitation Functions ◽  
Model Code ◽  
A Value ◽  
Stacked Foil Activation Technique

Excitation functions for the reactions (α,2n), (α,αn), (α,α2n), (α,α3n) and (α,2pn) have been measured using 57 Co as a target up to 50 MeV α-particle energy. The stacked foil activation technique and γ-ray spectroscopy method has been employed. Measured excitation functions are compared with the geometry dependent hybrid (GDH) model. A comparison shows that the pure equilibrium (EQ) compound reaction mechanism is incapable of reproducing the experimental data while the pre-equilibrium (PE) reaction mechanism along with equilibrium (EQ) decay, where it is considered that pre-equilibrium emission of particles take place prior to the establishment of the thermodynamical equilibrium of the system, is able to reproduce the experimental data. The GDH model code ALICE-91 has been used for theoretical calculations. A value of initial exciton number n0=4 with configuration (2 neutron + 2 proton + 0 hole) has been found to give the satisfactory reproduction of experimental excitation functions.

Nonequilibrium effects in α-particle-induced reactions in Cs and I

2000 ◽  
Vol 78 (2) ◽  
pp. 133-139 ◽  
Author(s):  
M K Bhardwaj ◽  
I A Rizvi ◽  
A K Chaubey
Keyword(s):  
Cross Sections ◽  
Gamma Ray ◽  
Theoretical Calculations ◽  
High Energy ◽  
Particle Energy ◽  
Substantial Contribution ◽  
Equilibrium Geometry ◽  
Activation Technique ◽  
Excitation Functions ◽  
Stacked Foil Activation Technique

The excitation functions for the reactions 127I(α,n)130Cs, 127I(α,2n)129Cs, 127I(α,4n)127Cs, 133Cs(α,2n)135La, and 133Cs(α,4n)133La have been measured up to 50 MeV alpha-particle energy using the stacked-foil activation technique and Ge(Li) gamma-ray spectroscopy. The measured cross sections were compared with theoretical calculations considering equilibrium as well as the pre-equilibrium geometry-dependent hybrid models of Blann. The high-energy tails of the excitation functions show a substantial contribution from pre-equilibrium emission. A general agreement is observed between the experimental results and theoretical predictions with an initial exciton configuration n0 = 4(2n + 2p + 0h).PACS No. 25.40-h

STUDY OF EXCITATION FUNCTIONS IN Rh(α, xn) Ag REACTIONS

1996 ◽  
Vol 05 (02) ◽  
pp. 345-352 ◽  
Author(s):  
M. AFZAL ANSARI ◽  
N.P.M. SATHIK ◽  
B.P. SINGH ◽  
M.G.V. SANKARACHARYULU ◽  
R. PRASAD
Keyword(s):  
Experimental Data ◽  
Compound Nucleus ◽  
Alpha Particle ◽  
Computer Code ◽  
Particle Energy ◽  
Activation Technique ◽  
Excitation Functions ◽  
Foil Activation ◽  
Alpha Particle Energy ◽  
Stacked Foil Activation Technique

The excitation functions for the reactions 103 Rh (α, n)106 m Ag , 103 Rh (α, 2n)105 Ag , and 103 Rh (α, 3n)104 Ag have been measured between 10 and 40 MeV alpha-particle energy, using the stacked foil activation technique. Excitation functions are also calculated theoretically using the Geometry Dependent Hybrid (GDH) model. The computer code ALICE/LIVERMORE-82 has been used which takes into account the pre-equilibrium contribution along with the equilibrium decay of the compound nucleus. It has been found that initial exciton number n0=4 gives a satisfactory reproduction of experimental data.

Cross sections for d-3H neutron interactions with samarium isotopes

2016 ◽  
Vol 104 (8) ◽  
Author(s):  
Junhua Luo ◽  
Chunlei Wu ◽  
Li Jiang ◽  
Long He
Keyword(s):  
Experimental Data ◽  
Neutron Flux ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Nuclear Model ◽  
Activation Technique ◽  
Incident Neutron ◽  
Reaction Threshold ◽  
Talys 1.6 ◽  
The Cross

Abstract:The cross sections for (n,x) reactions on samarium isotopes were measured at (d-T) neutron energies of 13.5 and 14.8 MeV with the activation technique. Samples were activated along with Nb and Al monitor foils to determine the incident neutron flux. Theoretical calculations of excitation functions were performed using the nuclear model codes TALYS-1.6 and EMPIRE-3.2 Malta with default parameters, at neutron energies varying from the reaction threshold to 20 MeV. The results were discussed and compared with experimental data found in the literature. At neutron energies 13.5 and 14.8 MeV, the cross sections of the

Non-equilibrium emission of neutrons in α-particle induced reactions with holmium

2008 ◽  
Vol 86 (3) ◽  
pp. 495-500 ◽  
Author(s):  
Avinash Agarwal ◽  
I A Rizvi ◽  
A K Chaubey
Keyword(s):  
Compound Nucleus ◽  
Computer Code ◽  
High Energy ◽  
Activation Technique ◽  
Excitation Functions ◽  
Equilibrium Reaction ◽  
Experimental Trend ◽  
Γ Ray ◽  
Stacked Foil Activation Technique ◽  
Equilibrium Emission

The stacked-foil activation technique followed by off line high-purity Ge γ-ray spectroscopy was used for the measurement of the excitation functions for energies up to 50 MeV for the 165Ho(α, 2n) 167Tm, 165Ho(α, 3n) 166Tm, and 165Ho(α, 4n) 165Tm reactions. The measured excitation functions were compared with theoretical predications considering equilibrium as well as pre-equilibrium reaction mechanisms according to the geometry-dependent hybrid (GDH) model of Blann using computer code ALICE-91. The high-energy parts of the excitation functions are due to the pre-equilibrium reaction mechanism, while the low-energy parts are mediated by compound-nucleus decay. It was found that the compound-nucleus-decay mechanism alone is unable to explain the experimental trend of our data. The pre-equilibrium fraction was also calculated. PACS Nos.: 22.55.–e, 27.60.+j

scholarly journals Kinetic Study on Esterification of Ascorbyl Oleate Catalyzed by Lipase NS 88011

2020 ◽  
Vol 11 (1) ◽  
pp. 8374-8388
Keyword(s):  
Experimental Data ◽  
Ascorbic Acid ◽  
Oleic Acid ◽  
Reaction Mechanism ◽  
Vitamin C ◽  
Kinetic Study ◽  
Immobilized Enzyme ◽  
Molar Ratio ◽  
A Value ◽  
Ping Pong

In this study, bisubstrate kinetics mechanism models were correlated with the experimental data of ascorbyl oleate using the new lipase preparation, Candida antarctica NS 88011, and kinetic parameters (Vmax, Km, and Ki) were estimated. The highest conversion (49.42 %) was observed at 1 h of reaction using the ascorbic acid/oleic acid molar ratio of 1:9, 70 ºC and 30 % of enzymatic loading. The Ping Pong Bi-Bi model showed better congruence with the experimental data for all the effects evaluated. The kinetic constants showed that the lipase had an identical affinity, with a value of 0.81 for both substrates and inhibitory constant (Ki) of ascorbic acid (1.959) much higher than oleic acid (0.0008). It has been demonstrated that lipase has good operational stability (14th cycle). The results obtained with the new immobilized enzyme are valuable to elucidate the reaction mechanism. In addition, it represents an important contribution to optimize the reaction and create strategies to increase the productivity of the esters of vitamin C.

scholarly journals Investigation of cross sections of deuteron induced nuclear reactions on selenium up to 50 MeV

2021 ◽  
Vol 57 (4) ◽  
Author(s):  
Ferenc Tárkányi ◽  
Sándor Takács ◽  
Ferenc Ditrói ◽  
Zoltán Szűcs ◽  
Károly Brezovcsik ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Gamma Ray ◽  
Nuclear Reactions ◽  
Particle Energy ◽  
Gamma Ray Spectrometry ◽  
Excitation Functions ◽  
On Line ◽  
Theoretical Model Codes ◽  
Activation Cross Sections

AbstractIn the frame of a systematic study of deuteron induced nuclear reactions on all elements, activation cross sections on $$^{\mathrm {nat}}$$ nat Se were investigated. Excitation functions were measured up to 50 MeV particle energy for production of $$^{\mathrm {82}}$$ 82 Br(m$$+)$$ + ) ,$$^{\mathrm {80m}}$$ 80 m Br, $$^{\mathrm {77}}$$ 77 Br(m$$+)$$ + ) ,$$^{\mathrm {76}}$$ 76 Br(m$$+)$$ + ) , $$^{\mathrm {75}}$$ 75 Br, $$^{\mathrm {75}}$$ 75 Se(cum), $$^{\mathrm {73}}$$ 73 Se(cum), $$^{\mathrm {76}}$$ 76 As,$$^{\mathrm {74}}$$ 74 As, $$^{\mathrm {73}}$$ 73 As(cum), $$^{\mathrm {72}}$$ 72 As and $$^{\mathrm {71}}$$ 71 As(cum) by using the activation method through stacked foil irradiation followed by off-line gamma-ray spectrometry. The experimental results were compared to the earlier experimental data and to excitation functions calculated with the ALICE-D and EMPIRE-D theoretical model codes and data given in the TENDL-2019 on-line library based on TALYS calculations.

Measurement and analysis of excitation functions for alpha-particle-induced reactions in rhenium

2004 ◽  
Vol 82 (3) ◽  
pp. 227-237
Author(s):  
N L Singh ◽  
M S Gadkari
Keyword(s):  
Cross Sections ◽  
Residual Nucleus ◽  
Reaction Cross ◽  
Activation Technique ◽  
Excitation Functions ◽  
Theoretical Predictions ◽  
Reaction Channels ◽  
Stacked Foil Activation Technique ◽  
The Individual ◽  
First Time

Excitation functions of the reactions 185Re[(α,n); (α,2n); (α,3n)] and 187Re[(α,n); (α,2n); (α,3n); (α,4n)] were investigated up to 50 MeV using the stacked-foil activation technique and high-purity germanium γ-ray spectroscopy method. Since the natural rhenium used as a target has two odd-mass stable isotopes of abundance 37.4% (185Re) and 62.6% (187Re), their activation in some cases gives the same residual nucleus through different reaction channels, but with very different Q values. In such cases, the individual reaction cross sections are separated with the help of the ratio of theoretical cross sections. The experimental cross sections were compared with the theoretical predictions considering equilibrium as well as pre-equilibrium contributions using code ALICE/90. It was found that the initial exciton configuration n0 = 4 (4p0h) appears to give a good fit to the experimental data. To the best of our knowledge, the excitation functions for 185Re[(α,n); (α,2n); (α,3n)] and 187Re[(α,3n); (α,4n)] reactions were measured for the first time. PACS No.: 25.55.–e

Measurements of excitation functions of α-particle induced reactions on natNi: possibility of production of the medical isotopes 61Cu and 67Cu

2018 ◽  
Vol 106 (2) ◽  
pp. 87-93 ◽  
Author(s):  
Md. Shuza Uddin ◽  
Kwangsoo Kim ◽  
Muhammad Nadeem ◽  
Sandor Sudár ◽  
Guinyun Kim
Keyword(s):  
Nuclear Model ◽  
Activation Technique ◽  
Isotopic Abundance ◽  
Energy Window ◽  
Excitation Functions ◽  
Model Calculations ◽  
Data Points ◽  
Stacked Foil Activation Technique ◽  
The Cost ◽  
Very High

AbstractExcitation functions of thenatNi(α,x)60,61Cu and64Ni(α,p)67Cu reactions were measured using the stacked-foil activation technique. The experimental data achieved were compared with literature data as well as with nuclear model calculations performed using the code TALYS-1.8. Integral yields from the respective thresholds to 44 MeV were deduced from the measured excitation curves. The >99% pure61Cu can be produced using the energy window of Eα=20→7 MeV, the yield amounting to 116 MBq/μAh. After a 2 h cooling time, the short-lived60Cu (T1/2=23 min) impurity will be reduced to <0.1%. Due to low isotopic abundance of64Ni, the enriched64Ni target would be needed for the production of67Cu via the (α,p) reaction. The cost would, however, be very high. In a few cases, particularly above 24 MeV, we have given new data points. In general, our measurements have strengthened the database.

Preequilibrium emission of multiparticles in α-induced reactions with 55Mn nucleus

1989 ◽  
Vol 67 (11) ◽  
pp. 1091-1096 ◽  
Author(s):  
I. A. Rizvi ◽  
M. K. Bhardwaj ◽  
M. Afzal Ansari ◽  
A. K. Chaubey
Keyword(s):  
Experimental Data ◽  
Hybrid Model ◽  
Spectroscopy Method ◽  
Activation Technique ◽  
Target Element ◽  
Geometry Dependent Hybrid Model ◽  
Foil Activation ◽  
Γ Ray ◽  
Stacked Foil Activation Technique ◽  
First Time

α-induced reactions on the target element Mn were investigated from 7 to 60 MeV, using the stacked-foil activation technique and the Ge(Li) γ-ray spectroscopy method. Six excitation functions for the reaction residues 58Co, 57Co, 56Co, 55Co, 54Mn, and 52gMn were measured, of which 55Mn (α,α3n) 52gMn was measured for the first time. The experimental data were compared with calculations considering equilibrium as well as preequilibrium reactions according to the geometry-dependent hybrid model of Blann (see Phys. Rev. Lett. 27, 337 (1971); 27, 700E (1971); 27, 1550E (1971)). The initial exciton number, n0 = 4, with different configurations was tested. It was found that the configuration (2n + 2p + oh) appears to give a good fit to the experimental data.

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