Polarization Transfer Measurement for 19-F and 39-K(p,n)

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Gamow-Teller Matrix Elements and the (p,n) Reaction

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Weak Interaction Matrix Elements and (p,n) Cross Sections

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

A Comparison of 37-Ca(p,n) Cross Sections to 37-Ca β-Decay

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Electron Cloud Generation And Trapping in a Quadrupole Magnet at the Los Alamos PSR

A diagnostic to measure electron cloud formation and trapping in a quadrupole magnet has been developed, installed, and successfully tested at PSR. Beam studies with this diagnostic show that the electron flux striking the wall in the quadrupole is comparable to or larger than in an adjacent drift. In addition, the trapped electron signal, obtained using the sweeping feature of diagnostic, was larger than expected and decayed very slowly with an exponential time constant of 50 to 100 {micro}s. Experimental results were also obtained which suggest that a significant fraction of the electrons observed in the adjacent drift space were seeded by electrons ejected from the quadrupole

Wider availability of PARMILA and recent improvements to PARMILA

PARMILA (Phase And Radial Motion in Ion Linear Accelerators) is a drift-tube linac (DTL) ion-beam dynamics code. Over its long life, many versions have developed. The Los Alamos Accelerator Code Group distributes a version, for which a manual is available. Unless otherwise specified, all mentions of PARMILA in this document refer to that LAACG-distributed version. Until recently, this documented and distributed version functioned only under CTSS. Users who wished to run on a different operating system needed to convert the code themselves. PARMILA now operates under UNICOS, a much more widely available CRAY operating system, and under VAX/VMS. This paper describes some new features of the code, and gives directions for obtaining the manual and the UNICOS and VMS versions of the code

Los Alamos Neutron Science Center (LANSCE) accelerator timing system upgrade

The Los Alamos Neutron Science Center (LANSCE) 800 MeV proton linear accelerator (linac) operates at a maximum repetition rate of twice the AC power line frequency, i.e. 120 Hz. The start of each machine cycle occurs a fixed delay after each zero-crossing of the AC line voltage. Fluctuations in the AC line frequency and phase are therefore present on all linac timing signals. Proper beam acceleration along the linac requires that the timing signals remain well synchronized to the AC line. For neutron chopper spectrometers, e.g., PHAROS at the Manuel Lujan Jr. Neutron Scattering Center, accurate neutron energy selection requires that precise synchronization be maintained between the beam-on-target arrival time and the neutron chopper rotor position. This is most easily accomplished when the chopper is synchronized to a stable, fixed frequency signal. A new zero-crossing circuit which employs a Phase-Locked Loop (PLL) has been developed to increase the phase and frequency stability of the linac timing signals and thereby improve neutron chopper performance while simultaneously maintaining proper linac operation. Results of timing signal data analysis and modeling and a description of the PLL circuit are presented

Intense Combined Source of Neutrons and Photons for Interrogation Based on Compact Deuteron RF Accelerator

AbstractInterrogation of special nuclear materials can benefit from mobile sources providing significant fluxes of neutrons (108/s at 2.5 MeV, 1010/s at 14.1 MeV) and of photons (>1012/s at 1-3 MeV). We propose a source that satisfies these requirements simultaneously plus also provides, via the reaction 11B(d,n)12C(γ15.1), a significant flux of 15-MeV photons, which are highly penetrating and optimal for inducing photo-fission in actinides. The source is based on a compact (< 5 m) deuteron RF accelerator that delivers an average current of a few mA of deuterons at 3-4 MeV to a boron target. The accelerator consists of a short RFQ followed by efficient inter-digital H-mode structures with permanent-magnet-quadrupole beam focusing [Kurennoy et al. (2012)], which suit perfectly for deuteron acceleration at low energies. Our estimates, based on recent measurements [Taddeucci et al. (2007)], indicate that the required fluxes of both neutrons and photons can be achieved at ∼1mA of 4-MeV deuterons. The goal of the proposed study is to confirm feasibility of the approach and develop requirements for future full- system implementation

Polarizing Transfer in 19-F and 39-K(p,n)

This research was sponsored by the National Science Foundation Grant NSF PHY-931478