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Half-Life of Polonium

Description: Abstract: "The half-life of polonium has been measured by a calorimetric method using samples several thousand times larger than have been previously available. The value is found to be 138.3 +/- 0.1% days."
Date: September 9, 1946
Creator: Beamer, William H. & Easton, William E.
Partner: UNT Libraries Government Documents Department

The Half Life of Am²⁴³

Description: This report calculates the alpha half-life of americium-243 and reporting a measurement error.
Date: 1953
Creator: Diamond, H.; Fields, Paul R.; Mech, Joseph; Inghram, Mark Gordon, {} & Hess, David C.
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

Radiation of Pu²⁴³

Description: "The radiations of Pu²⁴³ were studied with beta and gamma scintillation spectrometers alone and in coincidence. An incomplete disintegration scheme is deduced which leads to a total beta disintegration energy of 560 kev. A half-life of 4.98 ± 0.02 hours was observed."
Date: October 1952
Creator: Engelkemeir, D. W.; Fields, Paul R. & Huizenga, John R.
Partner: UNT Libraries Government Documents Department

EFFECTIVE HALF-LIFE OF CESIUM-137 IN VARIOUS ENVIRONMENTAL MEDIA AT THE SAVANNAH RIVER SITE

Description: During the operational history of the Savannah River Site (SRS), many different radionuclides have been released from site facilities into the SRS environment. However, only a relatively small number of pathways, most importantly {sup 137}Cs in fish and deer, have contributed significantly to doses and risks to the public. The “effective” half-lives (T{sub e}) of {sup 137}Cs (which include both physical decay and environmental dispersion) in Savannah River floodplain soil and vegetation and in fish and white-tailed deer from the SRS were estimated using long-term monitoring data. For 1974–2011, the T{sub e}s of {sup 137}Cs in Savannah River floodplain soil and vegetation were 17.0 years (95% CI = 14.2–19.9) and 13.4 years (95% CI = 10.8–16.0), respectively. These T{sub e}s were greater than in a previous study that used data collected only through 2005 as a likely result of changes in the flood regime of the Savannah River. Field analyses of {sup 137}Cs concentrations in deer collected during yearly controlled hunts at the SRS indicated an overall T{sub e} of 15.9 years (95% CI = 12.3–19.6) for 1965–2011; however, the T{sub e} for 1990–2011 was significantly shorter (11.8 years, 95% CI = 4.8–18.8) due to an increase in the rate of {sup 137}Cs removal. The shortest T{sub e}s were for fish in SRS streams and the Savannah River (3.5–9.0 years), where dilution and dispersal resulted in rapid {sup 137}Cs removal. Long-term data show that T{sub e}s are significantly shorter than the physical half-life of {sup 137}Cs in the SRS environment but that they can change over time. Therefore, it is desirable have a long period of record for calculating Tes and risky to extrapolate T{sub e}s beyond this period unless the processes governing {sup 137}Cs removal are clearly understood.
Date: December 12, 2013
Creator: Jannik, T.; Paller, M. & Baker, R.
Partner: UNT Libraries Government Documents Department

Lightest Isotope of Bh Produced Via the 209Bi(52Cr,n)260BhReaction

Description: The lightest isotope of Bh known was produced in the new {sup 209}Bi({sup 52}Cr,n){sup 260}Bh reaction at the Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. Positive identification was made by observation of eight correlated alpha particle decay chains in the focal plane detector of the Berkeley Gas-Filled Separator. {sup 260}Bh decays with a 35{sub -9}{sup +19} ms half-life by alpha particle emission mainly by a group at 10.16 MeV. The measured cross section of 59{sub -20}{sup +29} pb is approximately a factor of four larger than compared to recent model predictions. The influences of the N = 152 and Z = 108 shells on alpha decay properties are discussed.
Date: May 7, 2007
Creator: Nelson, Sarah L.; Gregorich, Kenneth E.; Dragojevic, Irena; Garcia, Mitch A.; Gates, Jacklyn M.; Sudowe, Ralf et al.
Partner: UNT Libraries Government Documents Department

THE FIRST ISOLATION OF AMERICIUM IN THE FORM OF PURE COMPOUNDS - THE SPECIFIC ALPHA-ACTIVITY AND HALF-LIFE OF Am241

Description: The microgram scale isolation and preparation of pure compounds of americium is described. Data are presented to show that the alpha-half-life of the isotope Am{sup 241} is 490 {+-} 14 years. The absorption spectrum of Am(III) in 1M nitric acid in the range 3500-8000 mu is given. The wave lengths of 10 of the most prominent lines in the copper spark emission spectrum of americium are given to the nearest 0.01 {angstrom}. Evidence is presented to show that the potential for the Am(III)-Am(IV) couple in acid solution is more negative than -2v and that the potential for the Am(II)-Am(III) couple is more positive than +0.9v.
Date: July 20, 1950
Creator: Cunningham, B.B. & Asprey, L.B.
Partner: UNT Libraries Government Documents Department

On Double-Beta Decay Half-Life Time Systematics

Description: Recommended 2{beta}(2{nu}) half-life values and their systematics were analyzed in the framework of a simple empirical approach. T{sub 1/2}{sup 2{nu}} {approx} 1/E{sup 8} trend has been observed for {sup 128,130}Te recommended values. This trend was used to predict T{sub 1/2}{sup 2{nu}} for all isotopes of interest. Current results were compared with other theoretical and experimental works.
Date: April 14, 2010
Creator: Pritychenko, B.
Partner: UNT Libraries Government Documents Department

The Half-Lives of Aluminum25 and Aluminum26

Description: The availability of separated isotopes of Mg makes it easy to determine the half life of Al{sup 26}, a member of the Wigner series which has long been suspected to have a half life of approximately 7 seconds, but which has not been confirmed because of the masking 7 second activity of Al{sup 26}. Mg{sup 24}, Mg{sup 25} and Mg{sup 26} (in the form of MgO) have been bombarded with protons from the Berkeley Linear Accelerator, with the following results: (1) Mg{sup 24} yields an activity of approximately 23 seconds half life, presumably due to Na{sup 21} from the reaction Mg{sup 24}(p,a)Na{sup 21}; (2) the Mg{sup 25} yields an activity of approximately 8 seconds half life, which they assign to the reaction Mg{sup 25}(p,n)Al{sup 25}; and (3) The Mg{sup 26} yields an activity of approximately 6 seconds half life, assigned to Al{sup 26} according to a similar reaction. It seems probable therefore that the 7 seconds half life normally given for Al{sup 26} is a mixture of these two activities.
Date: April 24, 1948
Creator: Bradner, Hugh & Gow, J.D.
Partner: UNT Libraries Government Documents Department

Nuclear Reactions of Arsenic with 190 Mev Deuterons

Description: Isotopes formed in the bombardment of {sub 33}As{sup 75} with 190 Mev deuterons range in atomic number up to 24 (or more) mass units lighter than As{sup 75}. Identification of these isotopes was based on chemical behavior and half-life determination. Relative yields have been calculated and show that 80% of the observed reactions produce isotopes within 8 mass units of As{sup 75}. Three new isotopes have been observed: 9.5 d. Se{sup 72} (K), 44 m, Se{sup 71} ({beta}{sup +}), and 52 m, As{sup 71} ({beta}{sup +}).
Date: January 21, 1948
Creator: Hopkins Jr, H.H. & Cunningham, B.B.
Partner: UNT Libraries Government Documents Department

TABLE OF RADIOISOTOPES ARRANGED ACCORDING TO HALF-LIFE

Description: The tabulated data on radioisotopes are taken directly from the General Electric Chart of the Nuclides, Fifth Edition. The half lives, decay particles and energies, gamma energies, and total energy or mass are included in the table. (J.E.D.)
Date: December 1, 1957
Creator: Daniels, E. comp.
Partner: UNT Libraries Government Documents Department

Measurement of the {sup 44}Ti half-life and its significance for supernova.

Description: In 1998, we reported the three-laboratory measurement of the {sup 44}Ti half-life which was determined relative to the well known value (5.2714 {+-} 0.0005 yr) of the {sup 60}Co half-life. We have continued the measurement at Argonne and Jerusalem and inclusion of data points for additional two years does not change our published value of 59.0 {+-} 0.6 yr.
Date: August 28, 1999
Creator: Ahmad, I.; Greene, J. P.; Kutschera, W. & Paul, M.
Partner: UNT Libraries Government Documents Department

Low Mass Francium and Emanation Isotopes of High AlphaStability

Description: Isotopes of francium with 126 or fewer neutrons have been looked for in bombardments of Th{sup 232} with 350 Mev protons from the 184-inch cyclotron. Fr{sup 212} with an apparent half-life of 19.3 minutes for branching decay by alpha emission (44%) to At{sup 208} and by orbital electron capture (56%) to Em{sup 212} has been found. Em{sup 212} is shown to be a 23-minute alpha-emitter. At{sup 208} decays primarily (99.5%) by orbital electron capture to Po{sup 208}, but shows 0.5% alpha-branching. The francium and emanation isotopes have alpha half-lives completely out of line with the predictions based on the previously known isotopes of these elements. Their high alpha stability is believed to be due to a closed shell of 126 neutrons in analogy to the behavior of elements 83-85. The non-existence of long-lived francium in nature is discussed in the terms of this and other recent work on francium isotopes.
Date: October 10, 1949
Creator: Hyde, E.K.; Ghiorso, A. & Seaborg, G.T.
Partner: UNT Libraries Government Documents Department

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

Half-Life for Double Beta-Decay

Description: Fireman(1) has reported the results of a rather difficult beta-particle coincidence counting experiment in which the decay of Sn{sup 124} by the simultaneous emission of two negative beta-particles, with a half-life between 0.4 x 10{sup 16} years and 0.9 x 10{sup 16} years, seems to have been observed. This note reports the results obtained from a different and somewhat simpler method of looking for the phenomenon of simultaneous emission of two beta-particles. These results are negative so far and show that this process is considerably less probable in the case chosen by us than in that reported by Fireman. The method consists of looking in uranium samples for 90-year Pu{sup 238} which would come from U{sup 238} by the double beta-particle mechanism since Np{sup 238} is heavier than U{sup 238}, which in turn is substantially heavier than Pu{sup 238}, in the isobaric triplet {sub 92}U{sup 238}-{sub 93}Np{sup 238}-{sub 94}Pu{sup 238}. This chemical method of investigation is particularly applicable to this isobaric triplet because there appears to be no other mechanisms to account for the Pu{sup 238} should it be found. The energetics of the situation are summarized in the following diagram, where the disintegration energies are derived from sources which may be traced through a recent compilation.
Date: October 21, 1949
Creator: Levine, C.A.; Ghiorso, A. & Seaborg, G.T.
Partner: UNT Libraries Government Documents Department

Radioactive Elements in the Standard Atomic Weights Table.

Description: In the 1949 Report of the Atomic Weights Commission, a series of new elements were added to the Atomic Weights Table. Since these elements had been produced in the laboratory and were not discovered in nature, the atomic weight value of these artificial products would depend upon the production method. Since atomic weight is a property of an element as it occurs in nature, it would be incorrect to assign an atomic weight value to that element. As a result of that discussion, the Commission decided to provide only the mass number of the most stable (or longest-lived) known isotope as the number to be associated with these entries in the Atomic Weights Table. As a function of time, the mass number associated with various elements has changed as longer-lived isotopes of a particular element has been found in nature, or as improved half-life values of an element's isotopes might cause a shift in the longest-lived isotope from one mass to another. In the 1957 Report of the Atomic Weights Commission, it was decided to discontinue the listing of the mass number in the Atomic Weights Table on the grounds that the kind of information supplied by the mass number is inconsistent with the primary purpose of the Table, i.e., to provide accurate values of 'these constants' for use in various chemical calculations. In addition to the Table of Atomic Weights, the Commission included an auxiliary Table of Radioactive Elements for the first time, where the entry would be the isotope of that element which was the most stable, i.e., the one with the longest known half-life. In their 1973 Report, the Commission noted that the users of the main Table of Atomic Weights were dissatisfied with the omission of values for some elements in that Table and it was ...
Date: August 4, 2007
Creator: Holden,N.E.
Partner: UNT Libraries Government Documents Department

SEARCH FOR AN 80-ms SPONTANEOUS FISSION ACTIVITY IN BOMBARDMENTS OF 249Bk WITH 15N

Description: A rotating drum system was used to search for an 80-ms spontaneous fission (sf) activity in the reaction of {sup 15}N with {sup 249}Bk. No such activity was found beyond a cross section limit of 0.3 {+-} 0.3 nb. A sf activity with a half-life of about 20 ms and a formation cross section of 12 nb at 82 MeV was observed. The identity of this activity has not been determined.
Date: January 1, 1980
Creator: Nitschke, J.M.; Fowler, M.; Ghiorso, A.; Leber, R.E.; Nurmia, M.J.; Somerville, L.P. et al.
Partner: UNT Libraries Government Documents Department

Reinvestigation of the Direct Two-proton Decay of the Long-lived Isomer 94Agm [0.4 s, 6.7 MeV, (21+)]

Description: An attempt to confirm the reported direct one-proton and two-proton decays of the (21+) isomer at 6.7(5) MeV in 94Ag has been made. The 0.39(4) s half-life of the isomer permitted use of a helium-jet system to transport reaction products from the 40Ca + natNi reaction at 197 MeV to a low-background area; 24 gas Delta E-(Si) E detector telescopes were used to identify emitted protons down to 0.4 MeV. No evidence was obtained for two-proton radioactivity with a summed energy of 1.9(1) MeV and a branching ratio of 0.5(3)percent. Two groups of one-proton radioactivity from this isomer had also been reported; our data confirm the lower energy group at 0.79(3) MeV with its branching ratio of 1.9(5)percent.
Date: March 5, 2009
Creator: Cerny, J.; Moltz, D. M.; Lee, D. W.; Perajarvi, K.; Barquest, B. R.; Grossman, L. E. et al.
Partner: UNT Libraries Government Documents Department

RADIOACTIVE ELEMENTS IN THE STANDARD ATOMIC WEIGHTS TABLE

Description: In the 1949 Report of the Atomic Weights Commission, a series of new elements were added to the Atomic Weights Table. Since these elements had been produced in the laboratory and were not discovered in nature, the atomic weight value of these artificial products would depend upon the production method. Since atomic weight is a property of an element as it occurs in nature, it would be incorrect to assign an atomic weight value to that element. As a result of that discussion, the Commission decided to provide only the mass number of the most stable (or longest-lived) known isotope as the number to be associated with these entries in the Atomic Weights Table. As a function of time, the mass number associated with various elements has changed as longer-lived isotopes of a particular element has been found in nature, or as improved half-life values of an element's isotopes might cause a shift in the longest-lived isotope from one mass to another. In the 1957 Report of the Atomic Weights Commission, it was decided to discontinue the listing of the mass number in the Atomic Weights Table on the grounds that the kind of information supplied by the mass number is inconsistent with the primary purpose of the Table, i.e., to provide accurate values of 'these constants' for use in various chemical calculations. In addition to the Table of Atomic Weights, the Commission included an auxiliary Table of Radioactive Elements for the first time, where the entry would be the isotope of that element which was the most stable, i.e., the one with the longest known half-life. In their 1973 Report, the Commission noted that the users of the main Table of Atomic Weights were dissatisfied with the omission of values for some elements in that Table and it was ...
Date: July 27, 2011
Creator: Holden, N.E.; Holden, N. & Holden,N.E.
Partner: UNT Libraries Government Documents Department

EFFECTIVE DOSIMETRIC HALF LIFE OF CESIUM 137 SOIL CONTAMINATION

Description: In the early 1960s, an area of privately-owned swamp adjacent to the US Department of Energy's Savannah River Site (SRS), known as Creek Plantation, was contaminated by site operations. Studies conducted in 1974 estimated that approximately 925 GBq of {sup 137}Cs was deposited in the swamp. Subsequently, a series of surveys--composed of 52 monitoring locations--was initiated to characterize and trend the contaminated environment. The annual, potential, maximum doses to a hypothetical hunter were estimated by conservatively using the maximum {sup 137}Cs concentrations measured in the soil. The purpose of this report is to calculate an 'effective dosimetric' half-life for {sup 137}Cs in soil (based on the maximum concentrations) and compare it to the effective environmental half-life (based on the geometric mean concentrations).
Date: January 9, 2008
Creator: Jannik, T; P Fledderman, P & Michael Paller, M
Partner: UNT Libraries Government Documents Department