Improved wavelengths and energy levels of doubly-ionized argon (Ar III)

New measurements of Ar III wavelengths between 508 Å and 4183 Å are combined with measurements from the literature to find improved values for the energy of most of the known levels in Ar III. Parameters derived from fitting the new level energies to an LS-coupling model are presented along with eigenvector compositions of the levels. On the basis of this analysis new designations are recommended for several levels

Magnetic analysis of the Li6(He3,t)Be6 reaction

The triton spectrum from the reaction Li6(He3,t)Be6 has been measured in a 61-cm double-focusing magnetic spectrometer at He3 bombarding energies of 10, 11, and 12 MeV, and at observation angles of 1.7° and 10°. A triton group corresponding to the Be6 ground-state transition was seen. The Q value for the ground-state transition is (-4.306±0.006) MeV, leading to a Be6-Li6 mass difference of 4.288±0.006 MeV, in good agreement with the values from the Li6(p,n)Be6 threshold. The width of the ground state of Be6 is (89±6) keV

Interview with Ward Whaling

An interview in four sessions, in April and May 1999, with Ward Whaling, professor of physics, emeritus, in the Division of Physics, Mathematics, and Astronomy. He recalls growing up outside Dallas and later Houston, Texas. Entered Rice University in 1941 and joined Army Signal Corps. Graduated with a BS in physics in February '44, and spent three months in the Signal Corps Officer Candidate School, Fort Monmouth, NJ, where he studied advanced radar techniques. Recalls his stint with the U.S. occupation forces in Bremen. Discharged in September 1946, he returned to Rice for graduate work, where he became a teaching assistant for William V. Houston; PhD 1947, with Thomas W. Bonner, thesis on the reactions of lithium-6 with deuterium. He recalls work with early Van de Graaff accelerators. Dr. Whaling became a research fellow at Caltech in 1949 (he joined the faculty as an assistant professor in 1952). At Rice, he had been working on energy levels of beryllium-7, which was of interest to a group at Caltech's Kellogg Radiation Laboratory. He joined the Kellogg group and helped build a magnetic spectrometer. He recalls that work and his colleagues Alvin Tollestrup, William A. Fowler, Charles C. and Thomas Lauritsen, and later Fay Ajzenberg-Selove, Charles A. Barnes, Ralph Kavanagh, Robert King. Discusses Caltech's postwar military projects. Recalls Fred Hoyle's work on nucleogenesis at Caltech and Hoyle's interactions with Kellogg group and Caltech astronomers. Offers his recollections of social life at Caltech, and of Robert Bacher's tenure as division chairman [1948-1962]. Recalls the musical shows that J. Kent Clark [professor of English 1947-1986] and Elliot Davis put together, and the Apicians, a dining club at the Athenaeum. There is an extensive discussion of the early days of astrophysics and nucleosynthesis at Caltech. Describes his duties as secretary for the Faculty Board (a post he has held since 1984) and the work of the Academic Freedom and Tenure Committee. Discusses his unrewarding year as RA [resident associate] in Fleming House in the mid-1950s and the undergraduate culture at Caltech. Became emeritus in 1993. Reflects on how much he has enjoyed teaching at Caltech, especially the laboratories. He concludes the interview with a discussion of his work on the scanning interferometer for the McMath solar telescope at Kitt Peak to measure atomic branching ratios

New method for determining relative oscillator strengths of atoms through combined absorption and emission measurements: Application to titanium (TiI)

The authors introduce a procedure that combines measurements of absorption and emission by atoms to obtain relative oscillator strengths that are independent of temperature determination in the sources and of assumptions regarding local thermodynamic equilibrium. The experimental observations are formed into sets of transitions and required to satisfy defined ratios. The screened data are adjusted with a least-squares program to obtain optimized relative oscillator strengths and constants relating the observations to these values. With appropriate choices of input observations, the constants are proportional to upper-level lifetimes and lower-level populations. The procedure is illustrated by the published data of Whaling et al. and Smith and Kühne for 16 transitions in TiI. The relative oscillator strengths resulting from this procedure have calculated uncertainties between 5 and 17% (∼ 95% confidence level). Evidence is presented to suggest that these uncertainties have been overestimated. Calculated oscillator strengths are normalized to the atomic-beam absorption measurements of Bell et al. and to the experimental lifetimes of Roberts et al. and Whaling et al. The absolute oscillator strengths are determined with an uncertainty of 7-18%. The results indicate that the published lifetime for the level y 3D20 of TiI should be increased by 24%

Improved wavelengths and energy levels of doubly-ionized argon (Ar III)

New measurements of Ar III wavelengths between 508 Å and 4183 Å are combined with measurements from the literature to find improved values for the energy of most of the known levels in Ar III. Parameters derived from fitting the new level energies to an LS-coupling model are presented along with eigenvector compositions of the levels. On the basis of this analysis new designations are recommended for several levels

The reaction energies of Ne21(d,α)F19 and Ne21(d,p)Ne22 from magnetic analysis

Separated isotopic targets of Ne21, which were produced at the Nobel Institute of Physics, have been used to measure the Q-values of the reactions (1) Ne21(d,α)F19, and (2) Ne21(d,p)Ne22. A double focusing magnetic spectrograph was used to compare the energy of the protons and alpha-particles from these reactions with the alpha-particles from ThC and ThC′. The angle of observation and the deuteron bombarding energy were chosen so that the particles being studied and the alpha-line used for energy calibration lay nearly side by side on the photographic plate used as a detector. The Q-values measured are 6.432±0.010 MeV for reaction (1) and 8.137±0.011 Mev for reaction (2). From these Q-values and the mass of F19 the atomic masses of Ne21 and Ne22 are obtained. Other alpha-groups from reaction (1) correspond to transitions to states in F19 at 0.113±0.008 Mev and 0.192±0.012 Mev above the ground state. Additional particle groups from N and Na contamination on the targets have been observed: The Q-values measured are 8.613±0.011 Mev for N14(d,p)N15 and 4.723±0.008 for Na23(d,p)Na24

Equilibrium charge distributions of C, N, Ar, and Fe in carbon

The equilibrium charge distributions have been measured for carbon and argon in the energy range from 370 to 1450 keV, for iron in the energy range from 190 to 1450 keV, and for nitrogen from 180 to 1450 keV. Equilibrium was established by passing accelerated ions through 10 μg/cm2 carbon foils. The ions of different charge were separated electrostatically and detected with a CsI(T1) scintillator. Additional measurements were made to ensure that equilibrium had been achieved and that the effect of the residual gas was small. The values of the charge fractions are thought to be correct to within ±5% and agree well with the limited available data

The stopping cross section of D2O ice

The energy loss of protons and deuterons in D2O ice has been measured over the energy range Ep=18-541 kev using the double focusing magnetic spectrometer to measure the energy of the particles after they have traversed a known thickness of the ice target. One method of measurement is used to determine relative values of the stopping cross section as a function of energy, another method measures the absolute values. The results are in very good agreement with the values calculated from Bethe's semi-empirical formula. Possible sources of error are considered and the accuracy of these measurements is estimated to be ±4 percent

Cross Section and Angular Distribution of the D(d,p)T Reaction

The D(d,p)T reaction cross section has been measured by two methods using D2O ice targets. For Ed from 206 to 516 kev, a double-focusing magnetic spectrometer was used to obtain the momentum spectrum of the protons and tritons, from which the reaction cross section can be determined. For Ed from 35 to 550 kev, the proton yield from a thick target was differentiated to obtain the cross section. Both thin and thick target methods were used to measure the angular distribution over the energy range Ed from 35 to 550 kev. The angular distribution is expressed in terms of a Legendre polynomial expansion. Various sources of experimental error are considered and the probable error of the total cross section is found to be ±5 percent

Neutrons from the Bombardment of Li6 by Deuterons

In the present experiments the neutron energy spectrum has been analyzed from cloud-chamber photographs of recoil protons in the direction of the deuteron beam. A target of Li2(6)SO4, 375 µg per cm^2 (about 150 kev at the bombarding energy used) was irradiated with 595-kev deuterons from the Rice Institute Van de Graaf generator. The low bombarding energy was chosen to minimize the neutrons from deuteron bombardment of carbon contamination on the target and on the tube wall in the analyzing magnet