A systematic experimental study of inclusive pion double charge exchange in 4He has been undertaken. The reaction 4He(pi+,pi-)4p was observed at incident energies 120, 150, 180, 240 and 270 MeV; the 4He(pi-,pi+)4n reaction was observed at incident energies 180 and 240 MeV. At each incident energy, the doubly differential cross section was measured at three to five outgoing pion laboratory angles between 25 deg and 130 deg. At each angle, cross sections were measured over the range of outgoing pion energies from 10 MeV up to the kinematic limit for the reaction in which the final state consists of the oppositely charged pion plus four free nucleons. The spectra of outgoing pions are strikingly different from those observed for the inclusive double charge exchange reaction in heavier nuclei, but resemble those observed in the (pi-,pi+) reaction in 3He. The forward-angle spectra in the 3He and 4He reactions exhibit a prominent peak at high outgoing pion energies. Interpretation of the peaks in 3He (4He) as a three- (four-)nucleon resonance is ruled out by kinematic analysis. The results of a calculation, wherein the double charge exchange reaction is assumed to proceed as two sequential single charge exchange interactions, suggest that the high-energy peak is naturally explained by this double scattering mechanism. Non-static treatment of the pi-N interactions and the inclusion of nuclear binding effects appear to be important in reproducing the shape of the energy spectra at forward angles.

Radiation monitoring systems based on the long-range alpha detection (LRAD) technique, such as the BNFL Instruments IonSens{trademark}, provide a single contamination measurement for an entire object rather than the more familiar individual readings for smaller surface areas. The LRAD technique relies on the ionization of ambient air molecules by alpha particles, and the subsequent detection of these ions, rather than direct detection of the alpha particles themselves. A single monitor can detect all of the ions produced over a large object and report a total contamination level for the entire surface of that object. However, both the unrestricted release limits specified in USDOE Order 5400.5 (and similar documents in other countries), and the definitions of radioactive waste categories, are stated in terms of contamination per area. Thus, conversion is required between the total effective contamination as measured by the LRAD-based detector and the allowable release limits. In addition, since the release limits were not written assuming an averaging detector system, the method chosen to average the assumed contamination over the object can have a significant impact on the effective sensitivity of the detector.

This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The collection of ions created by alpha particles in air is a powerful technique for detecting the presence of alpha-emitting radioactive contamination. These ions have a relatively long lifetime (greater than 5 seconds) in air so the ions can travel much longer distances than the alpha particles themselves. However, such ion detection is difficult when the object being surveyed is an insulating material. An insulating object does not release ions generated until the surface of the object has completely discharged. Thus, there are significant response-time problems with contamination on insulating objects. This project sought to investigate the technique of {open_quotes}flooding{close_quotes} the suspect object with ions prior to the actual contamination detection measurement. Our preliminary conclusion is that such flooding will enhance detection speed on insulating objects.

The relative photodetachment cross section for decay into the H(N = 2) channel by the 1P-degrees shape resonance in H- was measured, as well as that for decay into all channels. The branching ratio sigma(N = 2)/sigma(total) was computed for a series of energies between 10.95 and 11.3 eV after normalizing the cross sections to theoretical peak amplitudes. The maximum branching ratio (almost-equal-to 0.8) appears at an energy about 20 meV higher than the central energy of the resonance. Results are compared with recent theoretical calculations.

This report is intended as an extension if ''Wire Chamber Assembly Techniques,'' published as Los Alamos National Laboratory report LA-11237-MS. We describe a series of chamber assembly techniques that were developed after the procedures discussed in our first report. Although many of these techniques were developed using a set of wire chambers that were designed and built by the Advanced Nuclear Technology Group, many of our methods are of more general interest and can be applied to a variety of chamber designs. 9 refs., 14 figs.

The two major proposed first-order test theories for special relativity are shown to be equivalent. The results of many experimental tests of special relativity are given in terms of the free parameters of this unified test theory.

We report a measurement of parity nonconservation in the transmission of 800-MeV longitudinally polarized protons through an unpolarized, 1-m liquid-hydrogen target. The dependence of transmission on beam properties was studied to measure and to correct for systematic errors. The measured longitudinal asymmetry in the total cross section is ${A}_{L}=[+2.4\ifmmode\pm\else\textpm\fi{}1.1(\mathrm{statistical})\ifmmode\pm\else\textpm\fi{}0.1(\mathrm{systematic})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$.

Results of a measurement of parity nonconservation in the p↘–p total cross section at 800‐MeV are presented. The dependence of transmission on beam properties and correction for systematic errors are discussed. The measured longitudinal asymmetry is AL=(+2.4±1.1 (statistical ±0.1 (systematic))×10−7. A proposed experiment at 230 MeV is discussed.

We used the relativistic Doppler effect to shift the energy of the fourth-harmonic photons of a Nd-doped yttrium aluminum garnet laser into the range from 1.4 to 15.8 eV in a moving atom's reference frame by varying the angle of intersection theta between the laser beam and an 800-MeV atomic hydrogen (${\mathrm{H}}^{0}$) beam. We measured the intersection angle theta for several well known Lyman transitions (1s to np) in ${\mathrm{H}}^{0}$ and fitted these data by the form E=(${E}_{0}$/${g}_{0}$)\ensuremath{\gamma}(1+\ensuremath{\beta} costheta). The value of ${E}_{0}$/${g}_{0}$ obtained in this manner, compared with the measured value of ${E}_{0}$ for the laser photons, yielded ${g}_{0}$=1.000 04(27) at \ensuremath{\beta}\ensuremath{\simeq}0.84. The prediction of special relativity that ${g}_{0}$=1 is thus verified to an accuracy of 2.7\ifmmode\times\else\texttimes\fi{}${10}^{4}$.

We use the 800-MeV LAMPF ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ beam to Doppler-shift the energies of photons from a Nd:YAG laser (where YAG denotes yttrium aluminum garnet) up to the 10--13-eV range. Using these Doppler-shifted photons and calibrating our apparatus by observing the Lyman resonances in ${\mathrm{H}}^{0}$, we find that the energy of the first Feshbach resonance below n=2 in the ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ ion is 10.9264(6) eV. This energy is in good agreement with predictions and appears to indicate that the one-electron reduced-mass rydberg, rather than the infinite-mass rydberg, is appropriate to use for this Feshbach resonance.