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  Partner: UNT Libraries Government Documents Department
 Decade: 1940-1949
 Language: English
The Formation of U232 by Helium Ions of Thorium

The Formation of U232 by Helium Ions of Thorium

Date: April 14, 1948
Creator: Newton, Amos S.
Description: The production of U{sup 232} by the sum of {alpha},4n and {alpha},p 3n reactions on thorium has been studied. The cross section at an average energy of 37.5 Mev was 0.013 barns and the threshold for the reaction was about 30 Mev.
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Interium Report on An Exact Analysis of a Limited Plane Plasma in a Magnetic Field

Interium Report on An Exact Analysis of a Limited Plane Plasma in a Magnetic Field

Date: January 1, 1947
Creator: Tonka, Lewi
Description: Prior analyses of a plasma in a magnetic field have been limited, as far as the writer is aware, to cases in which the relative change in field over the orbital distance and the relative change in ion concentration are both small, or in which the relations have been viewed in a purely hydrodynamical way. The first approach excludes cases which can be of considerable interest, for it fails for a plasma edge. The second loses all sight of the structure imposed by the orbital motions.
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Loss of Radioactivity from Barium Carbonate Samples

Loss of Radioactivity from Barium Carbonate Samples

Date: January 9, 1948
Creator: Yankwich, Peter E.
Description: The exchange loss of radioactivity from solid samplos of barium carbonate through the agency of carbonic acid and its ions has been investigated under a variety of conditions. It is concluded that the losses observed are greatly dependent upon the method of sample preparation, in particular the nature or any heat treatment which the sample materials undergo.
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Monthly Progress Report No. 57 for January 1948

Monthly Progress Report No. 57 for January 1948

Date: January 1, 1948
Creator: Authors, Various
Description: This report gives a short summary of the work done in the following fields for the month of January 1948: (1) 184-inch cyclotron; (2) 60-inch cyclotron; (3) synchrotron; (4) linear accelerator; (5) experimental physics; (6) theoretical physics; (7) isotope research; (8) chemistry; (9) medical physics; and (10) health physics and chemistry.
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Degradation of Isotopic Lactate and Acetate

Degradation of Isotopic Lactate and Acetate

Date: February 24, 1948
Creator: Aronoff, S.; Haas, V.A. & Fries, B.A.
Description: A scheme of glucose degradation has been validated by the use of intermediates of known isotopic composition. In this scheme: glucose {yields} lactic acid {yields} CO{sub 2} (C-3,4) + acetic acid {yields} CO{sub 2} (C-2,5) + acetone {yields} iodoform (C-1,6) + acetate (C-1,6; 2,5), it was found that (a) in the oxidation of lactic acid, approximately 4.7% of the acetic acid was oxidized to CO{sub 2}; and (b) under the conditions prescribed, BaCO{sub 3} from the degradation of Ba acetate contained approximately 1.5% of the activity of the methyl group.
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Comparative Deposition of Zr95 in a Reticulo Endothelial Tumor to Normal Tissue in a Human Patient

Comparative Deposition of Zr95 in a Reticulo Endothelial Tumor to Normal Tissue in a Human Patient

Date: March 1, 1948
Creator: Low-Beer, B.V.; Scott, K.G.; Hamilton, J.G. & Stone, R.S.
Description: A test dose of Zr{sup 95} was given to a female patient which had a metastatic reticula endothelial tumor at the distal portion of the left femur. A comparison of the deposition of Zr{sup 95} showed greater uptake 24 hours after administration than any of the normal tissues investigated.
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High Voltage Pulsar For 184-inch Cyclotron Electric Deflector

High Voltage Pulsar For 184-inch Cyclotron Electric Deflector

Date: April 24, 1948
Creator: Kerns, Q.A.; Baker, W.R.; Edwards, R.F. & Farly, G.M.
Description: This paper describes a high voltage pulse generator developed to deflect the beam of the 184-inch cyclotron at Berkeley, California. The apparatus develops a deflecting potential of 200 kilovolts that rises from 10% to 90% of peak value in 0.1 microseconds. The unit employs two similar 100 kilovolt water cooled pulse transformers connected symmetrically about ground to the electric deflector bars. Water-cooled General Electric pulse capacitors are discharged through the two turn primary windings of the pulse transformers by triggering a battery of 16 paralleled Kuthe 5022 hydrogen thyratrons. Output voltages are developed across the 17 turn secondary winding of the pulse transformer. The transformer is mounted in an oil filled lucite case that provides both insulation and compact design.
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Nuclear Reactions of Arsenic with 190 Mev Deuterons

Nuclear Reactions of Arsenic with 190 Mev Deuterons

Date: January 21, 1948
Creator: Hopkins Jr, H.H. & Cunningham, B.B.
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 +}).
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Stars in Photographic Emulsions Initiated by Deuterons Part II. Theoretical

Stars in Photographic Emulsions Initiated by Deuterons Part II. Theoretical

Date: January 1, 1948
Creator: Horning, Wendell & Baumhoff, L.
Description: The theory of high energy nuclear stars depends on a theory of nuclear transparency and on a theory of nuclear evaporation. The transparency can be computed on the basis of a model proposed by R. Serber as soon as the interactions between the nucleons and the incident particle are known. The evaporation can be computed on the basis of the statistical model of the nucleus as soon as the nuclear entropy and binding energies of the evaporated particles are known. The calculations have been formulated with approximate values for the above interactions, entropies, and binding energies; and by means of various mathematical methods: a method of averages, a method of reaction integrals, and one using diffusion equations. Probability distributions have been obtained for the number of prongs per star, and distributions are being computed for the energy and angle of a prong. The results are in qualitative agreement with the observations on photographic emulsions described in Part I.
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Stars in Photographic Emulsions Initiated by Deuterons Part II. Theoretical

Stars in Photographic Emulsions Initiated by Deuterons Part II. Theoretical

Date: September 7, 1948
Creator: Horning, W. & Baumhoff, L.
Description: The theory of high energy nuclear stars depends on a theory of nuclear transparency and on a theory of nuclear evaporation. The transparency can be computed on the basis of a model proposed by R. Serber as soon as the interactions between the nucleons and the incident particle are known. The evaporation can be computed on the basis of the statistical model of the nucleus as soon as the nuclear entropy and binding energies of the evaporated particles are known. With approximate values for the above interactions, entropies, and binding energies, a probability distribution has been computed for the number of prongs per star. The results are in qualitative agreement with the observations on photographic emulsions described in Part 1.
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Phosphorus Turnover and Photosynthesis

Phosphorus Turnover and Photosynthesis

Date: November 1, 1947
Creator: Calvin, Melvin
Description: The participation of phosphorus in biological oxidation-reduction reactions of the type found in glycolysis ADP {ne} PO{sub 4}H{sup -} + 3-phosphoglyceraldehyde + DPN{sup +} = 3-phosphoglycerate{sup -} + 2H{sup +} + DPHN + ATP has suggested theories in which similar reactions are proposed for photosynthesis. In these theories the reducing power of photosynthesis is utilized not only for reduction of carbon dioxide but also, by means of coupled oxidations, for the generation of high-energy phosphate bonds, or in the last reference directly for the generation of high-energy phosphate. Since in these theories acyl phosphate is formed from inorganic phosphate, they are amenable to proof without isolation of particular intermediates, by means of radioactive phosphorus. It would be expected that the rate of conversion of inorganic phosphate to organic phosphate would be greater in light than in the dark. They have investigated this possibility under a variety of conditions and are unable to substantiate the theories.
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Spectral Lines of Curium from 3100 A to 4200 A

Spectral Lines of Curium from 3100 A to 4200 A

Date: April 7, 1948
Creator: Conway, John G. & Moore, Milton F.
Description: Fifty-four spectral lines of curium are listed together with estimated intensities. A brief description of the manner of taking the spectra and of measuring the lines is given. Three separate samples of curium, in all seven micrograms, were submitted for spectrochemical analysis. The samples in acidic solution (HCl) were evaporated on copper electrodes and analyzed as outlined for the copper spark method. An Applied Research Laboratories spark source was used. The spectra were taken on a Baird Associates spectrograph of the modified Eagle type which has a dispersion of 5.6 A/mm in the first order. Spectrum Analysis photographic plates were used and were processed according to the manufacturer's recommendations. The plates were placed in the projection comparator (also an Applied Research Laboratories Unit) and the lines measured using the scale associated with the projection screen. The copper lines of the spectra were used as a wavelength standard. In all 54 lines which we feel can be attributed to curium were found. These, together with an estimated intensity based on an arbitrary 1 to 10 scale, are listed in Table 1. Due to the high alpha-activity of curium special care had to be exercised in handling the samples. In this case ...
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Range Energy Relation for Protons in Nuclear Emulsions

Range Energy Relation for Protons in Nuclear Emulsions

Date: September 9, 1949
Creator: Bradner, H.; Smith, F.M.; Barkas, W.H. & Bishop, A.S.
Description: An experimental range-energy relation in Ilford C-2 emulsion has been obtained for proteins up to 39.5 Mev. In the region from 17 to 33 Mev the relation for dry emulsion is fitted by the empirical equation E{sub (MeV)} = 0.251 R{sub ({mu})} 0.581. Variations in water content due to changes in atmospheric humidity make several percent difference in range. The range in Ilford glass is found to be 18 {+-} 4 percent longer than in dry C-2 emulsion.
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Neutron Deficient Isotopes of Tellurium and Antimony

Neutron Deficient Isotopes of Tellurium and Antimony

Date: January 1, 1948
Creator: Lindner, M. & Perlman, I.
Description: While investigating the relative yields for the many reactions resulting from the irradiation of antimony with 200-Mev deuterons in the Berkeley 184-inch cyclotron several previously unreported isotopes of tellurium and antimony were encountered. The tellurium fraction when followed on a thin mica window counter could be resolved into half-life periods of 2.5 hrs, 6.0 days and a small amount of a long-lived component. The 2.5 hour period has not been further characterized with respect to mass number or mode of decay other than to note that the radiation is predominantly electrons. The 6.0-day period is accompanied by positrons which were shown to be due to a 3.5 minute antimony daughter which is undoubtedly the same activity assigned to Sb{sup 118} by Risser, Lark-Horowitz and Smith. The positron energy was found to be 3.1 {+-} 0.2 Mev by absorption in berylllum and from the end point of the energy distribution curve taken with a low-resolution beta-ray spectrometer. Gamma activity is also present with this period. The 6.0-day tellurium showed a high abundance of x-rays, little or no conversion electrons and some gamma-ray activity which could be due to the 3.5 minute antimony daughter. The tellurium fraction contained another component of 4.5-day ...
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The Estimation of Heats of Formation

The Estimation of Heats of Formation

Date: February 2, 1948
Creator: Brewer, Leo
Description: The procedure for estimation of heats of formation of compounds is illustrated by discussion of compounds of several of the elements of the actinide series. The procedure is particularly suited for lanthanide and actinide elements because of the similarity of the ionic radii and types of bonding.
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Excitation Curves of C12(p,pn)C11 and B11(p,n)C11 up to 32 MeV.

Excitation Curves of C12(p,pn)C11 and B11(p,n)C11 up to 32 MeV.

Date: April 20, 1948
Creator: Phillips, Robert & Panofsky, Wolfgang K.H.
Description: The reaction C{sup 12} (p,pn)C{sup 11} which has been studied by McMillan, Chubb and Miller for energies up to 100 Mev is an example of a reaction whose high energy behavior cannot be explained by a compound nucleus process. The purpose of the study was to investigate this reaction at the high resolution possible with the Berkeley linear accelerator near the excitation threshold. The excitation curve was obtained by stacking specially molded polystyrene (composition C{sub n}H{sub n}) foils of high uniformity and bombarding them in the proton beam. The resultant activity was then counted on a Geiger counter in standard geometry. The resultant curve is shown in Figure 1. An immediately evident feature is the sharp threshold of the reaction. The second derivative curve, illustrated in Figure 2, of the excitation shows an RMS width of 270 kV, the theoretical straggling width due to the foils of 170 kv, and the remaining width in accordance with the energy spread of approximately {+-} 100 kv half width of the linear accelerator. The data therefore are compatible with a sharp threshold for this reaction. This curve, incidentally, furnishes independent evidence as to the energy homogeneity of the linear accelerator beam.
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Excitation Function of the Reaction C12(n,2n)C11 at High Energies

Excitation Function of the Reaction C12(n,2n)C11 at High Energies

Date: November 1, 1947
Creator: Heckrotte, Wolff & Wolff, Peter
Description: The excitation curve for the reaction C{sup 12}(n,2n)C{sup 11} has been calculated for energies up to 100 Mev. The calculations were done as described in the preceding letter for the similar reaction of C{sup 12} under proton bombardment. The results of the calculations for 50% charge exchange are shown in Figure 1. The calculated cross section for the reaction at 90 Mev is: .011 barns for 100% charge exchange and .013 barns for 50% charge exchange. The experimental value is 0.025 {+-} .004 barns. The ratio of the cross section of the reaction C{sup 12}(pnpn)C{sup 11} to the cross section of the above reaction at 90 Mev is 5.8 for 100% charge exchange and 3.8 for 50% charge exchange. The experimental ratio is 2.7 at 90 Mev. This difference in cross sections between the two reactions is established by two factors. Firstly, there is the part played by charge exchange in the C{sup 12}(pnpn)C{sup 11} reaction which leads to excited N{sup 12} with the subsequent boiling off of a proton, while a similar exchange process cannot take place for the C{sup 12}(n2n)C{sup 11} reaction. Secondly, there is the difference between the contributions of the knock out process as a result ...
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Excitation Function of the Reaction C12(p,pn)C11 at High Energies

Excitation Function of the Reaction C12(p,pn)C11 at High Energies

Date: November 1, 1947
Creator: Heckrotte, W. & Wolff, Peter
Description: Chupp and McMillan have recently measured the excitation curve for the reaction C{sup 12}(pnpn)C{sup 11} at high energies. Using the model of the nucleus described by Serber, the excitation curve of the above reaction has been calculated for energies up to 100 Mev. The excitation of the nucleus is determined on the basis that the incident proton makes individual collisions with the nucleons, the transferred energy exciting the nucleus. n-p collisions are taken to be three times more probable than n-n or p-p collisions. Charge exchange is assumed. The calculations were made for both 50% and 100% charge exchange. The decay of the excited nucleus is treated by the usual evaporation mode.
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The Half-Lives of Aluminum25 and Aluminum26

The Half-Lives of Aluminum25 and Aluminum26

Date: April 24, 1948
Creator: Bradner, Hugh & Gow, J.D.
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.
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Half-Scale Model Tests on the Three Quarter Wave R.F. System for the 184-inch Frequency Modulated Cyclotron

Half-Scale Model Tests on the Three Quarter Wave R.F. System for the 184-inch Frequency Modulated Cyclotron

Date: December 30, 1947
Creator: Anderson, Robert L.
Description: Performance curves and test results on a half scale model of the radio frequency system designed to accelerate protons in the Berkeley 184-inch cyclotron are presented. This report is a sequel to K. R. Mackenzie's report on the three quarter wave radio frequency system for frequency modulated cyclotrons.
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THE RELATION OF BACKSCATTERING TO SELF-ABSORPTION

THE RELATION OF BACKSCATTERING TO SELF-ABSORPTION

Date: January 1, 1948
Creator: Yankwich, Peter E. & Weigl, John.
Description: The effects of backscattering upon self-absorption correction curves are demonstrated. Data are given for the backscattering powers of several substances for the beta radiations from C{sup 14}, and for se1f-absorption of samples of barium carbonate and wax, containing C{sup 14}, mounted on aluminum.
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Research Progress Meeting for March 11,1948

Research Progress Meeting for March 11,1948

Date: March 11, 1948
Creator: Wakerling, R.K.
Description: The linear accelerator is again in operation after a shutdown fore repairs and minor changes. Radiofrequency checks of the instrument were made while the Van de Graaff was open. The vacuum of the system is now very good, the base pressure being 1.7 x 10{sup -6} mm Hg with a rate of rise of 800 s/{micro}s. Some preliminary results have been obtained on the activation of carbon with protons. The experiments were done using 10 mil, 50 mg/cm{sup 2} polystyrene discs. The activation curve obtained is shown. The break shown in the curve was found on two separate runs and it yet unexplained. In another experiment a proton induced activity in nickel was found. This had a 3.3 second half-life. Positive mesons have been detected on plates exposed in the 184-inch cyclotron with an arrangement shown schematically. The beam ws allowed to strike a 1/16 inch carbon target, and the mesons, which are bent around by the magnetic field, were detected with photographic plaes placed beneath the circulating beam. A series of experiments were done in which the plates were placed at distances varying from 1-1/2 to 3/4 inch from the beam between 1/4 inch plates of copper. The plates ...
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Research Progress Meeting of February 19, 1948

Research Progress Meeting of February 19, 1948

Date: February 19, 1948
Creator: Wakerling, R.K.
Description: Much of the cloud chamber work has been directed toward obtaining the angular distribution of protons bombarded by deuterons from the 184-inch cyclotron. The observations have been restricted to those protons arising from neutrons of energy greater than 65 Mev. The cloud chamber used for this work is of 16-inch diruneter and employs a magnetic field of 14000 gauss. The chamber is filled with hydrogen at a pressure of 1/2 atmosphere; the vapor used is water and alchohol. Nearly 800 proton tracks were measured and calculated before analysis of the data indicated that the measuring procedure should be revised. They gave the angular and energy distributions shown in Figures 1 and 2. The discrepencies between the theoretical and experimental energy distribution of the neutrons shows that serious errors were being made. As a first check of possible sources of error, random parts of the data were remeasured. They indicated that errors in the measurements of the angles were being made that gave a mean deviation of about {+-} 2{sup o} in the beam angle and {+-} 4{sup o} in the dip angle. These errors were largest at large scatter angles. In addition, a more serious error occured in the measurements ...
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Research Progress Meeting of March 25, 1948

Research Progress Meeting of March 25, 1948

Date: March 25, 1948
Creator: Wakerling, R.K.
Description: This summary of the research progress meeting for March 25, 1948 covers the following topics: (1) Recent n-p scattering measurements; (2) Mass measurements of mesons; and (3) Naphthalene counters.
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