PRODUCTION AND PROPERTIES OF C15

1956 ◽  
Vol 34 (11) ◽  
pp. 1097-1111 ◽  
Author(s):  
R. A. Douglas ◽  
B. R. Gasten ◽  
Ambuj Mukerji
Keyword(s):  
Discharge Tube ◽  
Ground State ◽  
Half Life ◽  
Lower Energy ◽  
Gamma Ray ◽  
Plastic Scintillator ◽  
Branching Ratio ◽  
Parity Assignment ◽  
Energy Component ◽  
Beta Spectrum

Uniform thin C14 targets on 2500 Å nickel backings were prepared in a discharge tube containing acetylene (enriched to 28.8% C14). A NaI (Tl) crystal was used to measure the yield of C15 (2.25 ± 0.05 sec. half life) from C14(d, p)C15 from Ed = 1.3 to 3.0 Mev. A 7.5 ± 1.5 sec. activity was also observed, presumably N16 produced by C14(d, γ)N16. The C15 gamma-ray spectrum indicates only a 5.3-Mev. transition. A plastic scintillator was used to measure the C15 beta spectrum. End-point energies of 9.5 ± 0.3 and 4.5 ± 0.2 Mev. with a branching ratio of 4 to 1 favoring the lower energy component were observed. The results are consistent with a spin and parity assignment of 1/2(+) for the C15 ground state.

scholarly journals Nuclear Structure Investigations of some Medium-Weight Isotopes

2021 ◽  
Author(s):  
◽  
Gavin Wallace
Keyword(s):  
Nuclear Structure ◽  
Beta Decay ◽  
Cross Section ◽  
Gamma Rays ◽  
Half Life ◽  
Decay Scheme ◽  
Gamma Ray ◽  
Calculated Cross Section ◽  
Beta Spectrum ◽  
Gamma Ray Detectors

<p>This thesis describes the methods and results of investigations made to determine the decay schemes of three short-lived isotopes 112Ag, 114Ag and 116Ag. A total of 76 gamma-rays was observed with a Ge(Li) detector in the gamma-radiation which follows the Beta-decay of 112Ag to levels of 112Cd. gamma- gamma coincidence and angular correlation measurements were made with Ge(Li)-NaI(T1) and NaI(T1)-NaI(T1) systems. A decay scheme consistent with the present data is proposed. Cross sections for the reactions 112Cd(n,p)112Ag and 115In(n, alpha)112Ag were measured, and the half-life of the 112Ag decay was found to be 3.14 plus-minus 0.01 hr. The decay scheme of 114Ag was studied with Ge(Li) gamma-ray detectors and plastic Beta-ray detectors. 9 of the 11 gamma-rays observed in the decay were incorporated into 114Cd level structure previously determined by conversion electron measurements on the 113Cd(n,gamma)114Cd reaction. The endpoint energy of the Beta-decay was determined as 4.90 plus-minus 0.26 MeV; no branching was evident in the Beta-spectrum. A decay scheme is proposed for which the Beta-branching was deduced from the measured gamma-ray yield and a calculated cross section value for the 114Cd(n,p)114Ag reaction. The 114Ag half-life was determined as 4.52 plus-minus 0.03 sec; a search for a previously reported isomeric state of 114Ag was unsuccessful. Ge(Li) and NaI(T1) gamma-ray detectors were used to study the direct and coincidence spectra that result from the decay of 116Ag, the half-life of which was found to be 2.50 plus-minus 0.02 min. 53 gamma-rays were observed from this decay. The Beta-branching to the 17 excited states of 116Cd in the proposed decay scheme was derived from the measured gamma-ray yield and a calculated cross section value for the 116Cd(n,p)Ag reaction. Spin and parity assignments for ihe energy levels of 116Cd are made. An investigation of the applicability of two collective models to nuclear structure typical of the Cd nuclei studied demonstrated that one of the models was misleading when applied to vibrational nuclei. A potential function was developed in the other model to extend the investigation to include a study of the transition between extremes of collective motion. This was used to examine the correspondence between nuclear level schemes representative of rotational and vibrational excitations.</p>

MESONIC WEAK DECAY OF Λ–HYPERNUCLEI: A NEW TOOL FOR HYPERNUCLEAR SPECTROSCOPY

2010 ◽  
Vol 19 (05n06) ◽  
pp. 1109-1116
Author(s):  
S. BUFALINO
Keyword(s):  
Ground State ◽  
Charged Pion ◽  
Branching Ratio ◽  
Weak Decay ◽  
Precision Measurements ◽  
Parity Assignment ◽  
Spin Parity ◽  
Mesonic Decay ◽  
Magnetic Analysis ◽  
First Time

The FINUDA experiment has performed a systematic study of the Mesonic Weak Decay (MWD) of Λ hypernuclei by analyzing all the data collected from 2003 up to 2007. Negatively charged pion spectra from mesonic decay were measured with magnetic analysis for the first time for [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text]. Branching ratio Γπ-/Γtot were derived from the measured spectra. Based on these measurements, the spin-parity assignment 1/2+ for [Formula: see text] and 5/2+ for [Formula: see text] ground-state are confirmed and a spin-parity 3/2+ for [Formula: see text] ground-state is assigned for the first time. Ideas for precision measurements of MWD at the J-PARC accelerator's complex are finally presented.

Decay of 103Ag

1969 ◽  
Vol 47 (4) ◽  
pp. 419-427 ◽  
Author(s):  
H. Bakhru ◽  
R. I. Morse ◽  
I. L. Preiss
Keyword(s):  
Gamma Rays ◽  
Compound Nucleus ◽  
Ground State ◽  
Half Life ◽  
Decay Scheme ◽  
Gamma Ray ◽  
Mass Difference ◽  
Direct Interaction ◽  
Direct Process ◽  
Silver Compound

The reaction 14N + 11B forming a silver compound nucleus and the direct interaction of 107Ag + 14N were utilized to produce the isotope 103Ag. In both instances the 103Ag results from the subsequent evaporation of nucleons from either the Ag compound nucleus or from the 105Ag* reaction intermediate in the case of the direct process. The decay of this isotope was studied using Ge(Li) detectors as well as with standard scintillation counters. The beta- and gamma-ray measurements confirm three beta groups of maximum energies 1.31 ± 0.05 MeV (60%), 1.03 ± 0.05 (30%), and 0.500 ± 0.1 MeV (10%) and gamma rays of energies 0.118, 0.148, 0.235, 0.268, 0.420, 0.540, 0.555, 0.585, 0.655, 0.740, 1.002, 1.1, 1.14, 1.27, 1.36, and 1.56 MeV all decaying with a half-life 1.1 h. Coincidence studies show that the 0.118 MeV gamma ray is in coincidence with 0.148, 0.511, 0.555, 0.740, 1.0, and 1.1 MeV gamma rays; the 0.148 MeV gamma ray with the 0.118, 0.511, 0.555, 0.740, 1.0, and 1.1 MeV gamma rays; the 0.235 MeV gamma ray with the 0.420, 0.511, 0.585, 0.740, 1.04, and 1.13 MeV gamma rays; the 0.540 MeV gamma ray with the 0.511 and 0.820 MeV gamma rays; and the 0.820 MeV gamma ray with the 0.511 and 0.740 MeV gamma rays only. Two beta groups of maximum energies 1.03 and 0.5 MeV are observed to be in coincidence with the 0.148 and 0.268 MeV transitions and with the 0.555 and 0.820 MeV gamma rays as a gate, only the beta group of energy 0.5 ± 0.1 MeV appears. Based on the above observation, a decay scheme of 103Ag is proposed and the results are discussed. The half-life of 118 keV level is measured by delayed coincidence and found to be (1.9 ± 0.4) × 10−9 s indicating an M1 multipolarity for this transition. The mass difference between the ground state of 103Ag and 103Pd is found to be 2.32 MeV.

Lifetimes in 32S

1970 ◽  
Vol 48 (1) ◽  
pp. 47-55 ◽  
Author(s):  
R. W. Ollerhead ◽  
T. K. Alexander ◽  
O. Häusser
Keyword(s):  
Gamma Rays ◽  
Ground State ◽  
Doppler Shift ◽  
State Transition ◽  
Gamma Ray ◽  
Branching Ratio ◽  
Dipole Transition ◽  
Average Lifetime ◽  
Line Shapes ◽  
Doppler Shift Attenuation

Lifetimes have been measured for five levels in 32S. The levels were populated by inelastic scattering of protons, and the gamma rays were detected at angles between 0° and 127° using a 40 cm3 Ge(Li) detector mounted inside a split annular NaI(Tl) crystal. The spectrometer was used simultaneously as both an escape-suppressed and a three-crystal pair spectrometer. Decay schemes and lifetimes have been determined using thick targets of PbS, MoS2, and sulfur cooled to 77 °K. Lifetime information was obtained both from analysis of the observed gamma-ray line shapes and from analysis of the Doppler shift attenuation in the different target materials. The two methods of analysis agree within the errors. A weak ground-state transition was observed from the J = 3 level at 5.012 MeV, establishing its parity as negative. Analysis of the line shape observed at 0° and the Doppler shift attenuation gave an average lifetime of 7.5 ± 0.5 × 10−13 s. The observed branching ratio (4 ± 0.4% to the ground state) implies an E3 enhancement of 20 ± 2.4 Weisskopf units (W.u.). A similar analysis gave a lifetime of 4.9 ± 0.9 × 10−13 s for the J = 1 level at 4.699 MeV, which implies that the dipole transition to the ground state is highly retarded. Lifetimes have also been measured for levels at 3.780 MeV [Formula: see text], 4.288 MeV (7.4 ± 0.6 × 10−14 s), and 5410 MeV (1.9 ± 0.2 × 10−13 s); the transition strengths are tabulated and discussed.

scholarly journals Nuclear Structure Investigations of some Medium-Weight Isotopes

2021 ◽  
Author(s):  
◽  
Gavin Wallace
Keyword(s):  
Nuclear Structure ◽  
Beta Decay ◽  
Cross Section ◽  
Gamma Rays ◽  
Half Life ◽  
Decay Scheme ◽  
Gamma Ray ◽  
Calculated Cross Section ◽  
Beta Spectrum ◽  
Gamma Ray Detectors

<p>This thesis describes the methods and results of investigations made to determine the decay schemes of three short-lived isotopes 112Ag, 114Ag and 116Ag. A total of 76 gamma-rays was observed with a Ge(Li) detector in the gamma-radiation which follows the Beta-decay of 112Ag to levels of 112Cd. gamma- gamma coincidence and angular correlation measurements were made with Ge(Li)-NaI(T1) and NaI(T1)-NaI(T1) systems. A decay scheme consistent with the present data is proposed. Cross sections for the reactions 112Cd(n,p)112Ag and 115In(n, alpha)112Ag were measured, and the half-life of the 112Ag decay was found to be 3.14 plus-minus 0.01 hr. The decay scheme of 114Ag was studied with Ge(Li) gamma-ray detectors and plastic Beta-ray detectors. 9 of the 11 gamma-rays observed in the decay were incorporated into 114Cd level structure previously determined by conversion electron measurements on the 113Cd(n,gamma)114Cd reaction. The endpoint energy of the Beta-decay was determined as 4.90 plus-minus 0.26 MeV; no branching was evident in the Beta-spectrum. A decay scheme is proposed for which the Beta-branching was deduced from the measured gamma-ray yield and a calculated cross section value for the 114Cd(n,p)114Ag reaction. The 114Ag half-life was determined as 4.52 plus-minus 0.03 sec; a search for a previously reported isomeric state of 114Ag was unsuccessful. Ge(Li) and NaI(T1) gamma-ray detectors were used to study the direct and coincidence spectra that result from the decay of 116Ag, the half-life of which was found to be 2.50 plus-minus 0.02 min. 53 gamma-rays were observed from this decay. The Beta-branching to the 17 excited states of 116Cd in the proposed decay scheme was derived from the measured gamma-ray yield and a calculated cross section value for the 116Cd(n,p)Ag reaction. Spin and parity assignments for ihe energy levels of 116Cd are made. An investigation of the applicability of two collective models to nuclear structure typical of the Cd nuclei studied demonstrated that one of the models was misleading when applied to vibrational nuclei. A potential function was developed in the other model to extend the investigation to include a study of the transition between extremes of collective motion. This was used to examine the correspondence between nuclear level schemes representative of rotational and vibrational excitations.</p>

scholarly journals Time-Resolved Investigation of the Molecular Chemiluminescence SrI(A2∏1/2,3,2,B2∑+→X2∑+) and the Atomic Resonance Fluorescence Sr(53P1→51S0) Following The Pulsed Dye Laser Generation Of Sr(53PJ) in the Presence of CF3I

1995 ◽  
Vol 16 (2) ◽  
pp. 121-138 ◽  
Author(s):  
S. Antrobus ◽  
D. Husain ◽  
Jie Lei ◽  
F. Castaño ◽  
M. N. Sanchez Rayo
Keyword(s):  
Ground State ◽  
Branching Ratio ◽  
Atomic Emission ◽  
Electronic Energy ◽  
Dye Laser ◽  
Pulsed Dye Laser ◽  
Laser Generation ◽  
Buffer Gas ◽  
Resonance Fluorescence ◽  
Time Resolved

A time-resolved investigation is presented of the electronic energy distribution in SrI following the collision of the optically metastable strontium atom, Sr [5s5p(3PJ)], with the molecule CF3I. Sr[5s5p(3PJ)], 1.807 eV above its 5s2(1S0) electronic ground state, was generated by pulsed dye-laser excitation of ground state strontium vapour to the Sr(53P1) state at , λ =689.3 nm {Sr(53P1←51S0)} at elevated temperature (840 K) in the presence of excess helium buffer gas in which rapid Boltzmann equilibration within the 53PJ spin-orbit manifold takes place. Time resolved atomic emission from Sr(53P1→51S0) at the resonance transition and the molecular chemiluminescence from SrI(A2∏1,2,3/2,B2∑+→X2∑+) resulting from reaction of the excited atom with CF3I were recorded and shown to be exponential in character. SrI in the A2∏1/2,3/2 (172.5, 175.4 kJ mol-1) and B2∑+ (177.3 kJ mol-1) states are energetically accessible on collision by direct-I-atomic abstraction between Sr(3P) and CF3I. The first-order decay coefficients for the atomic and molecular emissions are found to be equal under identical conditions and hence SrI(A2∏1/2,3/2, B2∑+) are shown to arise from direct I- atom abstraction reactions. The molecular systems recorded were SrI (A2∏1/2→X2∑+, Δv=0, λ=694 nm), SrI(A2∏3/2→X2∑+, Δv=0, λ=677 nm) and SrI(B2∑+→X2∑+) (Δv=0, λ=674 nm), dominated by the Δv=0 sequences on account of Franck-Condon considerations. The combination of integrated m61ecular and atomic intensity measurements yields estimates of the branching ratios into the specific electronic states, A1/2, A3/2 and B, arising from Sr(53PJ)+CF3I which are found to be as follows: A1/2,1.2 × 10-2; A3/2, 6.7 × 10-3; B, 5.1 × 10-3 yielding ∑SrI(A1/2+A3/2+B)=2.4 × 10-2. As only the X, A and B states SrI are accessible on reaction, assuming that the removal of Sr(53PJ) occurs totally by chemical removal, this yields an upper limit for the branching ratio into the ground state of ca. 98%. The present results are compared with previous time-resolved measurements on excited states of strontium halides that we have reported on various halogenated species resulting from reactions of Sr(53PJ), together with analogous chemiluminescence studies on Sr(3PJ) and Ca(43PJ) from molecular beam measurements.

THE DECAY OF Pm149

1960 ◽  
Vol 38 (12) ◽  
pp. 1577-1585 ◽  
Author(s):  
Agda Artna ◽  
Margaret E. Law
Keyword(s):  
High Resolution ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Conversion Coefficient ◽  
Beta Spectrum ◽  
Multichannel Analyzer ◽  
Coincidence Spectrometer ◽  
Beta Spectrometer ◽  
Beta Group

The 52.8-hour activity of Pm149 has been investigated using a high resolution beta spectrometer, a lens type coincidence spectrometer, and a scintillation spectrometer in conjunction with a multichannel analyzer. The beta spectrum was found to consist of two groups with maximum energies of 1.072 ± 0.002 Mev and 0.786 ± 0.004 Mev, and intensities of 97.1 ± 0.4% and 2.9 ± 0.4% respectively. A gamma ray of energy 285.7 ± 0.3 kev was found to be in coincidence with the 0.786-Mev beta group. No other gamma rays with intensities greater than 0.1% were found. The K conversion coefficient for the 286-kev transition was measured to be 0.075 ± 0.008. This together with the values of 6.5 ± 0.7 and 4 ± 1 obtained for the K/L and L/M conversion ratios respectively indicate that this transition is M1 in character with less than 10% E2 admixture.

VUV FRAGMENTATION OF SOME HYDROFLUOROCARBON CATIONS STUDIED USING COINCIDENCE TECHNIQUES

2002 ◽  
Vol 09 (01) ◽  
pp. 153-158 ◽  
Author(s):  
WEIDONG ZHOU ◽  
D. P. SECCOMBE ◽  
R. Y. L. CHIM ◽  
R. P. TUCKETT
Keyword(s):  
Kinetic Energy ◽  
Ab Initio ◽  
Ground State ◽  
Lower Energy ◽  
Lone Pair ◽  
Electronic States ◽  
Photoelectron Spectra ◽  
Highest Occupied Molecular Orbital ◽  
Impulsive Model ◽  
Lone Pair Electrons

Threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has been used to investigate the decay dynamics of the valence electronic states of the parent cation of several hydrofluorocarbons (HFC), based on fluorine-substituted ethane, in the energy range 11–25 eV. We present data for CF 3– CHF 2, CF 3– CH 2 F , CF 3– CH 3 and CHF 2– CH 3. The threshold photoelectron spectra (TPES) of these molecules show a common feature of a broad, relatively weak ground state, associated with electron removal from the highest-occupied molecular orbital (HOMO) having mainly C–C σ-bonding character. Adiabatic and vertical ionisation energies for the HOMO of the four HFCs are presented, together with corresponding values from ab initio calculations. For those lower-energy molecular orbitals associated with non-bonding fluorine 2pπ lone pair electrons, these electronic states of the HFC cation decay impulsively by C–F bond fission with considerable release of translational kinetic energy. Appearance energies are presented for formation of the daughter cation formed by such a process (e.g. CF 3– CHF +), together with ab initio energies of the corresponding dissociation channel (e.g. CF 3– CHF + + F ). Values for the translational kinetic energy released are compared with the predictions of a pure-impulsive model.

GAMMA-RAY BURSTS AS VHE-UHE SOURCES

2008 ◽  
Vol 17 (09) ◽  
pp. 1319-1332
Author(s):  
PETER MÉSZÁROS
Keyword(s):  
Cosmic Rays ◽  
Gamma Rays ◽  
Lower Energy ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Model Parameters ◽  
Fundamental Interaction ◽  
Acceleration Mechanism ◽  
Inverse Compton ◽  
Tev Gamma Rays

Gamma-ray bursts are capable of accelerating cosmic rays up to GZK energies Ep ~ 1020 eV, which can lead to a flux at Earth comparable to that observed by large EAS arrays such as Auger. The semi-relativistic outflows inferred in GRB-related hypernovae are also likely sources of somewhat lower energy cosmic rays. Leptonic processes, such as synchrotron and inverse Compton, as well as hadronic processes, can lead to GeV-TeV gamma-rays measurable by GLAST, AGILE, or ACTs, providing useful probes of the burst physics and model parameters. Photo-meson interactions also produce neutrinos at energies ranging from sub-TeV to EeV, which will be probed with forthcoming experiments such as IceCube, ANITA and KM3NeT. This would provide information about the fundamental interaction physics, the acceleration mechanism, the nature of the sources and their environment.

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