Pion double charge exchange on 4He

The doubly differential cross sections for the $^4$He$(\pi^+,\pi^-) 4p$ reaction were calculated using both a two-nucleon sequential single charge exchange model and an intranuclear cascade code. Final state interactions between the two final protons which were the initial neutrons were included in both methods. At incident pion energies of 240 and 270 MeV the low-energy peak observed experimentally in the energy spectrum of the final pions can be understood only if the contribution of pion production is included. The calculated cross sections are compared with data.Comment: 25 pages, 9 figure

Recoil correction to the bound-electron g factor in H-like atoms to all orders in αZ\alpha Z

The nuclear recoil correction to the bound-electron g factor in H-like atoms is calculated to first order in $m/M$ and to all orders in $\alpha Z$. The calculation is performed in the range Z=1-100. A large contribution of terms of order $(\alpha Z)^5$ and higher is found. Even for hydrogen, the higher-order correction exceeds the $(\alpha Z)^4$ term, while for uranium it is above the leading $(\alpha Z)^2$ correction.Comment: 6 pages, 3 tables, 1 figur

Measurement of inclusive quasielastic scattering of polarized electrons from polarized ³He

We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized 3He gas target. This measurement represents the first demonstration of a new method for studying electromagnetic nuclear structure: the scattering of polarized electrons from a polarized nuclear target. The measured asymmetry is in good agreement with a Faddeev calculation and supports the picture of spin-dependent quasielastic scattering from polarized 3He as predominantly scattering from a polarized neutron

Determination of the neutron electric form factor in quasielastic scattering of polarized electrons from polarized ³He

We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized ³He gas target. The asymmetry is measured at kinematics sensitive to the transverse-longitudinal response function RTL(Q2,ω). The value of the neutron electric form factor GEn(Q2=0.16 (GeV/c2))=+0.070±0.100±0.035 is extracted from the asymmetry using a Faddeev calculation of the ³He wave function

He→3(e→e′) quasielastic asymmetry

Measurements of the spin-dependent asymmetry in scattering longitudinally polarized electrons from polarized He3 at quasielastic kinematics are reported. The measurements were made at two kinematics and spin angles, one sensitive to the helicity-dependent transverse-longitudinal interference response function, RTL′, and the other to the helicity-dependent transverse response function, RT′. For the experiment a metastability exchange optically pumped polarized He3 target was used; a general discussion of the technique used to polarized the He3, along with the details of the design and operation of the target system, are presented here. A comparison is made of the world’s data on the He→3(e→,e′) quasielastic asymmetry with several theoretical predictions, including calculations that use the plane wave impulse approximation and a fully spin-dependent spectral function. There is good agreement between data and theory at the current level of experimental precision

Some outstanding issues in pion scattering at energies above the {Delta} resonance

The {Delta}(1232) resonance dominates pion-nucleon scattering at energies below 300 MeV, the region in which pion-nucleus scattering has been well studied using spectrometers at the meson factories. Above this energy region little pion-nucleus scattering data exists. Recently, spectrometers at Brookhaven, LAMPF, KEK, and DUBNA have been used to obtain initial data for pion-nucleus scattering in this energy region. In this talk we review some data that have been obtained using the LAS spectrometer at LAMPF

Status of a new switchyard design for LANSCE

Funding was recently received to study modifications of a section of the LANSCE beam switchyard. At present, the switchyard is used to deliver a proton beam to experimental Area A and an H{sup {minus}}-ion beam down Line D. The total H{sup {minus}} repetition rate is 120 Hz, 100 Hz is transported to the Weapons Neutron Research (WNR) area. The remaining 20 Hz is injected into the Proton Storage Ring (PSR). In order to provide H{sup {minus}} beam to other experimental areas without interfering with the PSR operations, a new design of the switchyard is in progress. The authors are presently investigating a solution that would use pulsed kicker magnets to deflect a fraction of the WNR H{sup {minus}} beam down a separate existing beam-line at the demand of the experimenters

Proton radiographic and numerical of colliding, diverging PBX-9502 detonations.

The Proton radiographic shot PRAD0077 was designed to study the interaction of colliding, diverging PBX-9502 detonations. The shot consisted of a 50 mm by 50 mm cylinder of PBX-9502 initiated on the top and bottom at the axis by a SE-1 detonator and a 12 mm by 12 mm cylinder of 9407. Seven radiographs were taken at times before and after the detonation collision. The system was modeled using the one-dimensional SIN code with C-J Burn in plane and spherically diverging geometry and using the two-dimensional TDL code with C-J Burn and Forest Fire. The system was also modeled with the recently developed AMR Eulerian reactive hydrodynamic code called NOBEL using Forest Fire. The system results in a large dead or nonreactive zone as the detonation attempts to turn the corner which is described by the model using Forest Fire. The peak detonation pressure achieved by the colliding diverging detonation is 50 gpa and density of 3.125 mg/ml which is about the same as that achieved by one-dimensional spherically diverging 9502 detonations but less than the one-dimensional plane 9502 peak colliding detonation pressure of 65 gpa and density of 3.4 mg/ml. The detonation travels for over 10 mm before it starts to expand and turn the corner leaving more than half of the explosive unreacted. The resulting diverging detonation is more curved than a one-dimensional spherical diverging detonation and has a steeper slope behind the detonation front. This results in the colliding pressure decaying faster than one-dimensional colliding spherical diverging pressures decay. The calculations using Forest Fire reproduce the major features of the radiograph and can be used to infer the colliding detonation characteristics