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Nitrogen 12

Description: N{sup 12} is shown to have a half life of 12.5 {+-} 1 milliseconds, and a positron upper limit of 16.6 {+-} 0.2 Mev. It is produced by the reaction C{sup 12}(p,n)N{sup 12}, and has a threshold proton energy of 20.0 Mev. This indicates that N{sup 12} is within about 200 Kev of being unstable against proton emission. The mass of N{sup 12} is 12.0228 {+-} 0.00015, and the beta transition is allowed.
Date: January 19, 1949
Creator: Alvarez, Luis W.
Partner: UNT Libraries Government Documents Department

THE ROLE OF THE CYCLOTRON IN MEDICAL RESEARCH

Description: The uses of radioactive isotopes in medical research can be conveniently divided into three principal categories; namely, the applications as tracers for the study of metabolic phenomena, as diagnostic aids in clinical medicine, and finally their role in therapy. Frequently radioisotopes available from the chain-reacting pile do not have a sufficient degree of specific activity for satisfactory use. A number of radioisotopes which can be produced with high specific activity in the pile possess half-lives too short to be of any practical value. Then, there are a few cases in which the desired radioisotope may be made in the pile with high specific activity, but concomitantly there is formed another radioisotope of the same element whose half-life is of such duration as to render its use hazardous in man. Finally, there are several elements of biological and medical interest whose radioactive isotopes can be produced only by the cyclotron.
Date: April 19, 1950
Creator: Hamilton, Joseph G.
Partner: UNT Libraries Government Documents Department

Measurement of the 208Pb(52Cr, n)259Sg Excitation Function

Description: The excitation function for the 208Pb(52Cr, n)259Sg reaction has been measured using the Berkeley Gas-filled Separator at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. The maximum cross section of pb is observed at a center-of-target laboratory-frame energy of 253.0 MeV. In total, 25 decay chains originating from 259Sg were observed and the measured decay properties are in good agreement with previous reports. In addition, a partial excitation function for the 208Pb(52Cr, 2n)258Sg reaction was obtained, and an improved 258Sg half-life of ms was calculated by combining all available experimental data.
Date: March 19, 2010
Creator: Folden III, C.M.; Dragojevic, I.; Dullmann, Ch.E.; Eichler, R.; Garcia, M.A.; Gates, J.M. et al.
Partner: UNT Libraries Government Documents Department

Proton Emission from Gamow Resonance

Description: We demonstrated that it is possible to calculate the complex energy of the deformed Gamow state with a precision that is high enough so that the half-life calculated from the imaginary part of the energy is meaningful. We also performed a comparison between non-adiabatic and adiabatic calculations. It can be concluded that, in many cases, the corrected adiabatic treatment cannot be used as a substitute for the full non-adiabatic calculations.
Date: October 19, 2001
Creator: Vertse, T.
Partner: UNT Libraries Government Documents Department

On the half-life of {sup 44}Ti

Description: One of the few long-lived gamma-ray emitting radioisotopes expected to be produced in substantial quantities during a supernova explosion is {sup 44}Ti. The relevant portions of the decay schemes of {sup 44}Ti and its daughter {sup 44}Sc are shown. {sup 44}Ti decays to {sup 44}Sc emitting {gamma} rays of 68 and 78 keV. {sup 44}Sc subsequently decays with a 3.93-hour half life to {sup 44}Ca emitting an 1,157-keV {gamma}ray. This characteristic 1,157-keV {gamma} ray from the decay of {sup 44}Ti has recently been observed from the supernova remnant Cas A. In order to compare the predicted {gamma}-ray flux to that actually observed from this remnant, one must know the half-life of {sup 44}Ti. However, published values for this quantity range from 46.4 to 66.6 years. Given that the Cas A supernova is believed to have occurred approximately 300 years ago, this translates to an uncertainty by a factor of 4 in the amount of {sup 44}Ti ejected by this supernova. Thus, in order to provide an accurate and reliable value for this important quantity, the authors have performed a new experiment to determine the half-life of {sup 44}Ti. The authors produced {sup 44}Ti via the {sup 45}Sc(p,2n) reaction using 40 MeV protons from the Lawrence Berkeley National Laboratory`s 88-Inch Cyclotron. In the present experiment, the authors attempted to use all three {sup 44}Ti {gamma}-ray lines to determine its half life. However, analysis of the {sup 241}Am and {sup 137}Cs lines produced an incorrect value for the half life of each of these isotopes. On the other hand, the analysis of the {sup 22}Na line produced a result that agreed to within 0.5% of the known value of 2.603 years. Thus, they decided to concentrate their effort on the analysis of the 1,157-keV line. The half life of {sup 44}Ti that ...
Date: June 19, 1996
Creator: Norman, E.B.; Browne, E.; Chan, Y.D.; Goldman, I.D.; Larimer, R.M.; Lesko, K.T. et al.
Partner: UNT Libraries Government Documents Department