410 research outputs found
Regolith history from cosmic-ray-produced isotopes
A statistical model is given for soil development relating meteoroid impacts on the moon to cosmic-ray-produced isotopes in the soil. By means of this model, the average lunar mass loss rate during the past 1.4 aeons is determined to be 170g/sq cm aeon and the soil mixing rate to be approximately 200 cm/aeon from the gadolinium isotope data for the Apollo 15 and 16 drill stems. The isotope data also restrict the time variation of the meteoroid flux during the past 1.4 aeons
Radioactivities in returned lunar materials
Results from a carbon-14 study in size fractions of lunar soil are reported. The 10 to 30 micrometers and 74 to 124 micrometers size fraction results were supplemented by 30 to 37 micrometers results that are given in this report. The gases from the less than 10 micrometers fraction were extracted and purified and carbon-14 counting is now in progress. Meteorites were also studied using carbon-14, with emphasis directed to those recently discovered in the Antarctic
Radioactivities in returned lunar materials and in meteorites
Carbon 14 terrestial ages were determined with low level minicomputers and accelerator mass spectrometry on 1 Yamato and 18 Allan Hills and nearby sited meteorites. Techniques for an accelerator mass spectrometer which make C(14) measurements on small samples were developed. Also Be(10) concentrations were measured in Byrd core and Allan Hills ice samples
Radioactivities in returned lunar materials and in meteorites
Carbon-14 measurements were made for meteorites with a Van der Graaf accelerator. Accelerator C-14 dating improved the precision by a factor of ten, allowed the use of smaller sample sizes, and gave speedier results than C-14 dating with counters. A methodology for determining the terrestrial ages of several antarctic meteorites is described and the results are listed
Titanium spallation cross sections between 30 and 584 MeV and Ar-39 activities on the moon
The production cross sections of Ar39 for Ti spallation at 45-, 319-, 433-, and 584-MeV proton energies were measured to be 0.37 + or - 0.09, 12.4 + or - 3.7, 9.1 + or - 2.7, and 17.8 + or - 6.2 mb, respectively. Normalized Ar39 production rates and activities are also derived for protons above 40 MeV and for three differential proton spectra of the type approximately E(- alpha). It is concluded that, even for samples of high-Ti content, Ti spallation by solar protons below 200-MeV energy does not contribute significantly to their Ar39 radioactivity
The stopping rate of negative cosmic-ray muons near sea level
A production rate of 0.065 + or - 0.003 Ar-37 atom/kg min of K-39 at 2-mwe depth below sea level was measured by sweeping argon from potassium solutions. This rate is unaffected by surrounding the solution by paraffin and is attributed to negative muon captures and the electromagnetic interaction of fast muons, and not to nucleonic cosmic ray component. The Ar-37 yield from K-39 by the stopping of negative muons in a muon beam of a synchrocyclotron was measured to be 8.5 + or - 1.7%. The stopping rate of negative cosmic ray muons at 2-mwe depth below sea level from these measurements and an estimated 17% electromagnetic production is 0.63 + or - 0.13 muon(-)/kg min. Previous measurements on the muon stopping rate vary by a factor of 5. Our value is slightly higher but is consistent with two previous high values. The sensitivity of the Ar-37 radiochemical method for the detection of muons is considerably higher than that of the previous radiochemical methods and could be used to measure the negative muon capture rates at greater depths
Nurses Alumni Association Bulletin, Fall 1996
1996-1997 Meeting Dates Calendar
1997 Annual Luncheon-Meeting Notice Inside
Officers and Committee Chairs
Bulletin Publication Committee
1996-1997 Meeting Dates Calendar
The President\u27s Message
Treasurer\u27s Report
News About Our Graduates
Letter To Jefferson Nurses
Fiftieth Anniversary
Resume\u27 of Minutes of Alumni Association Meetings
Alumni Office News
Nursing Up-Date 1995-1996
Scholarship Funds At Work
Diploma School of Nursing Alumni Association-Mabel C. Prevost Scholarship Report 1995
Women In Military Service For America Memorial Foundation
Operation Support Freedom - Humanitarian Aid to Kiev
The Best Mousetrap - Computers In Nursing
Christmas, As A Prisoner Of War
Restroom Policy
Happy Birthday
Committee Reports Bulletin Development Relief Fund Satellite Scholarship Social
Luncheon Photos
In Memoriam, Names of Deceased Graduates
Class News
Membership Application
Relief Fund Application
To Order: A Chronological History and Alumni Directory From TJU Bookstore
Scholarship Fund Applicatio
Pins, Transcripts, Class Address List, Change of Address Forms
Campus Ma
- …