We present critical assembly reaction rate data, and modeling of the same using the recently released ENDF/B-VII library. While some of the experimental measurements were performed as long as 50 years ago, the results have not been widely used/available outside of Los Alamos. Over the years, a variety of target foils were fabricated and placed in differing neutron spectrum/fluence environments within critical assemblies. Neutron-induced reactions such as (n,γ), (n,2n), and (n,f) on these targets were measured, typically referenced to 235 U(n,f) or 239 Pu(n,f). Because the cross section for the latter reactions are now well known, these experiments provide a rich data set for testing evaluated cross sections. Due to the large variety of critical assemblies that were historically available at Los Alamos, it was possible to make measurements in spectral environments ranging from hard (Pu Jezebel, center of Pu Flattop) through intermediate (Big Ten) to degraded (reflector region of Flattop). This broad range of configurations allows us to test both the cross section magnitudes and their energy dependencies. We will present data, along with reaction rate predictions using primarily MCNP5 in conjunction with ENDF/B-VII, for a number of target nuclei, including iridium, isotopes of uranium (e.g., 233, 235, 237, 238), neptunium (237), plutonium (239), and americium (241).

The recently completed 100-MeV H+ Isotope Production Facility (IPF) at the LANSCE will provide radioisotopes for medical research and diagnosis, for basic research and for commercial use. A change to the LANSCE accelerator facility allowed for the installation of the IPF. Three components make up the LANSCE accelerator: an injector that accelerates the H+ beam to 750-KeV, a drift-tube linac (DTL) that increases the beam energy to 100-MeV, and a side-coupled cavity linac (SCCL) that accelerates the beam to 800-MeV. The transition region, a space between the DTL and the SCCL, was modified to permit the insertion of a kicker magnet (23 o kick angle) for the purpose of extracting a portion of the 100-MeV H+ beam. A new beam line was installed to transport the extracted H+ beam to the radioisotope production target chamber. This paper will describe the commissioning and initial operating experiences of IPF.

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The Los Alamos Neutron Science Center (LANSCE) is installing two beam lines to both improve operational tuning and provide new capabilities. The Isotope Production Facility (IFF) will provide isotopes for medical purposes by using the H/sup +/ beam spur at 100 MeV and the Switchyard Kicker Upgrade (SYK) will allow the LANSCE 800-MeV H/sup -/ beam to be rapidly switched between various beam lines within the facility. The beam position instrumentation for both of these beam lines uses a microstripline beam position monitor (BPM) with a 50-mm or 75-mm radius. The cable plant is unique in that it unambiguously verifies the operation of the complete position instrumentation. The processing electronics use a log ratio technique with error correction such that it has a dynamic range of -12 dBm to -85 dBm with errors less than 0.15 dB within this range. This paper will describe the primary components of these measurement systems and provide initial data of their operation.

Within the halo experiment presently being conducted at the Low Energy Demonstration Accelerator (LEDA) at Los Alamos National Laboratory, specific beam instruments that acquire horizontally and vertically projected particle-density distributions out to approximately 10/sup 5/:1 dynamic range are located throughout the 52-magnet halo lattice. We measure the core of the distributions using traditional wire scanners, and the tails of the distribution using water-cooled graphite scraping devices. The wire scanner and halo scrapers are mounted on the same moving frame whose location is controlled with stepper motors. A sequence within the Experimental Physics and Industrial Control System (EPICS) software communicates with a National Instruments LabVIEW virtual instrument to control the motion and location of the scanner/scraper assembly. Secondary electrons from the wire scanner 0.033-mm carbon wire and protons impinging on the scraper are both detected with a lossy-integrator electronic circuit. Algorithms implemented within EPICS and in Research System's Interactive Data Language subroutines analyze and plot the acquired distributions. This paper describes this beam profile instrument, describes our experience with its operation, compares acquired profile data with simulation, and refers to other detailed papers.

The Low-Energy Demonstration Accelerator (LEDA), assembled and operating at Los Alamos National Laboratory, provides the platform for obtaining measurements of high-power proton beam-halo formation. Control system software and hardware have been integrated and customized to enable the production of real-time beam-halo profiles. The Experimental Physics and Industrial Control System (EPICS) hosted on a VXI platform, Interactive Data Language (IDL) programs hosted on UNIX platforms, and LabVIEW (LV) Virtual Instruments hosted on a PC platform have been integrated and customized to provide real-time, synchronous motor control, data acquisition, and data analysis of data acquired through specialized DSP instrumentation. These modules communicate through EPICS Channel Access (CA) communication protocol extensions to control and manage execution flow ensuring synchronous data acquisition and real-time processing of measurement data. This paper describes the software integration and management scheme implemented to produce these real-time beam profiles

This paper will discuss the operational experience with the Ionization Chamber Beam Loss Monitors (ICBLM) in the Low Energy Demonstration Accelerator facility at LANL. LEDA is a test bed for a 6.7 MeV, cw, 100 mA proton radio frequency quadrupole (RFQ). There are three ICBLMs located in a short beam transport downstream of the RFQ. (This transport is called HEBT for High Energy Beam Transport.) Their function is to convey beam loss information to the operators and to protect the accelerator from being damaged by large beam spills. Signals from the ionization chambers are ten times less than expected. This results in a signal to drift ratio of 0.4 for a 1 mA beam loss and prevents protection of the machine below 2.5 mA loss. Since it is important to protect the machine down to 0.2 mA loss, improvements in and alternatives to the ICBLM are being investigated and will be implemented.

The LEDA facility has been used to characterize the pulsed- and cw-beam performance of a 6.7-MeV, 100-mA radio frequency quadrupole (RFQ). Diagnostic instrumentation, primarily located in a short beam transport downstream of the RFQ, allowed facility commissioners and operators to measure and monitor the RFQ's accelerated and total beam transmission, beam loss, bunched beam current, beam energy and output phase, and beam position. Transverse beam profile measurements are acquired under both low and high duty- factor pulsed beam conditions using a slow wire scanner and a camera that images beam-induced fluorescence. The wire scanner is also used to acquire transverse beam emittance information using a technique known as a quad scan. This paper reviews the measurement performance and discusses some of the resulting data.

The Low Energy Demonstration Accelerator (LEDA) facility located at Los Alamos National Laboratory (LANL) accelerates protons to an energy of 6.7 MeV and current of 100 mA operating in either a pulsed or cw mode. Of key importance to the commissioning and operations effort is the Beam Position Monitor system (BPM). The LEDA BPM system uses five micro-stripline beam position monitors processed by log ratio processing electronics with data acquisition via a series of custom TMS320C40 Digital Signal Processing (DSP) boards. Of special interest to this paper is the operation of the system, the log ratio processing, and the system calibration technique. This paper will also cover the DSP system operations and their interaction with the main accelerator control system.

The Low Energy Demonstration Accelerator (LEDA) facility located at Los Alamos National Laboratory (LANL) accelerates protons to an energy of 6.7 MeV and current of 100 mA operating in either a pulsed or cw mode. Two types of current measurements are used. The first is an AC or pulsed-current measurement which uses three LANL built toroids. They are placed in the beamline in such a way as to measure important transmission parameters and act as a differential current-loss machine protection system. The second system is a DC current measurement used to measure cw beam characteristics and uses toroids from Bergoz Inc. There are two of these systems, so they can also be used for transmission measurements. The AC system uses custom processing electronics whereas the DC system uses a modified Bergoz((R)) electronics system. Both systems feature data acquisition via a series of custom TMS320C40 Digital Signal Processing (DSP) boards. Of special interest to this paper is the operation of these systems, the calibration technique, the differential current loss measurements and fast-protection processing, current droop characteristics for the AC system, and existing system noise levels. This paper will also cover the DSP system operations and their interaction with the main accelerator control system.

Beam diagnostic instrumentation is being developed for the LEDA, a 6.7-MeV, 100-mA-cw proton accelerator, presently being commissioned at the Los Alamos National Laboratory (LANL). This instrumentation will be the basis for much of the Accelerator Production of Tritium and the Spallation Neutron Source linac. Located in the LEDA injector and the high energy beam transport (HEBT) this initial instrumentation suite's purpose is to verify the RFQ pulsed and cw operation. The instrumentation include a series of DC, pulsed- and bunched-beam current measurements from which RFQ beam-transmission efficiency will be determined. Ionization-chamber beam loss measurements are mounted above the HEBT and provide input signals to a fast equipment protection system. Central beam phase and energy measurements provide RFQ longitudinal performance information. Beam position measurements provide information to properly center the beam within the HEBT beam pipe. Finally, two types of transverse profile measurements including a slow wire scanner and a video fluorescence monitor provide beam width and projection information in the LEDA HEBT. This paper will discuss these measurements developed for LEDA and summarize how they performed during RFQ verification experiments.

An experiment on the Ground Test Accelerator (GTA) for the Neutral Particle Beam (NPB) at Los Alamos commissioned the intermediate matching section (IMS) and a single 3.2-MeV drift tube linac (DTL). A diagnostic platform or D-plate was used at the output of the DTL in order to measure various beam parameters. The D-plate and other diagnostic devices located in the IMS, provided measurement of the horizontal and vertical beam position, current, energy, and output phase. These instruments were installed to perform a complete beam jitter analysis based on the current beamline configuration to better understand the causes of any jitter sources as well as to prepare for the initial design of future feedback control systems. The study explored all types of jitter for various beamline configurations. Both interpulse jitter (jitter from pulse to pulse) and intrapulse jitter (jitter within each macropulse) were investigated. Spectral and statistical time analyses were used. Spectral analysis was employed to gain an understanding of the spectral contributions of various jitter sources to determine the degree of correction possible. Statistical time analysis gave a good overall representation of the jitter magnitude and allowed easy comparison of jitter for different beamline configurations, as well as an easy method for determining consistent problems