My Life in Nuclear Physics, Photography, and Opera

I sketch my life as an experimental nuclear physicist, beginning as a graduate student at Harvard University from 1948 to 1951, then as a postdoctoral fellow at the Cavendish Laboratory from 1951 to 1952, and finally as a faculty member at the University of Minnesota from 1952 until my retirement in 1991. I also carried out research at the Niels Bohr Institute in Copenhagen, Indiana University, and Los Alamos National Laboratory, and I participated in a number of summer schools and international conferences on nuclear physics. I also have worked in photography and opera. Over the years, I met and collaborated with many people in many walks of life who became friends for life.     

Analysis of prompt fission neutron spectrum and multiplicity for 237Np（n,f） in the frame of multi-modal Los Alamos model

The improved version of Los Alamos model with the multi-modal fission approach is used to analyse the prompt fission neutron spectrum and multiplicity for the neutron-induced fission of 237Np. The spectra of neutrons emitted from fragments for the three most dominant fission modes (standard Ⅰ, standard Ⅱ and superlong) are calculated separately and the total spectrum is synthesized. The multi-modal parameters contained in the spectrum model are determined on the basis of experimental data of fission fragment mass distributions. The calculated total prompt fission neutron spectrum and multiplicity are better agreement with the experimental data than those obtained from the conventional treatment of the Los Alamos model.     

Joseph Rotblat: Moral Dilemmas and the Manhattan Project

John Fitzgerald Kennedy famously said, “One man can make a difference and every man should try.”1 Joseph Rotblat (1908–2005) was the quintessence of Kennedy’s conviction. He was the only scientist who left Los Alamos after it transpired that the atomic bomb being developed there was intended for use against adversaries other than Nazi Germany. I explore Rotblat’s early research in Warsaw and Liverpool, which established his reputation as a highly capable experimental physicist, and which led him to join the Manhattan Project at Los Alamos in 1944. I examine his motivation for resigning from the project in 1945, and the unwillingness of his fellow scientists to follow suit, which draws attention to the continuing discourse on the responsibility of scientists for the consequences of their research.     

Randomly rattled ratchets

Summary Ratchets are anisotropic periodic potentials. Particles subject to ratchet forces and simultaneously to thermal and nonthermal fluctuations can rectify the nonequilibrium noise, thereby extracting energy from incoherent and otherwise symmetric random forces. In this paper I describe some simple models which illustrate this phenomenon, highlighting two particular mechanisms leading to fluctuation-induced current. Paper presented at the International Workshop ?Fluctuations in Physics and Biology: Stochastic Resonance, Signal Processing and Related Phenomena?, Elba, 5–10 June 1994. Address after July 1, 1994: Center for Nonlinear Studies, MS-B258, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.     

Neutrino interactions in dense stellar matter

Weak-interaction rates play an important role in the birth of neutron stars in core collapse supernova and their subsequent thermal evolution. In this paper, I highlight the role of strong interactions and phase transitions in calculations of neutrino scattering and emission rates in dense stellar matter.Received: 1 November 2002, Published online: 15 July 2003PACS: 13.15.+g Neutrino interactions - 13.20.-v Leptonic and semileptonic decays of mesons - 26.50.+x Nuclear physics aspects of novae, supernovae, and other explosive environments - 26.60.+c Nuclear matter aspects of neutron starsPresent address: Los Alamos National Laboratory, P.O. Box 1663, MS B283, Los Alamos, NM 87545, USA     

Nanoscale Science and Technology at Los Alamos National Laboratory

Research in the emerging field of nanoscale science and technology has grown steadily at Los Alamos National Laboratory since 1990. This article summarizes some of this work, examining research highlights within the seven key categories of nanoscience in which Los Alamos has ongoing projects, capabilities, and facilities: (1) Materials and chemistry, (2) Theory and modeling, (3) Bioscience, (4) Investigative tools and facilities, (5) Sensors and devices, (6) Synthesis and fabrication, and (7) Education and outreach. Future research horizons are indicated throughout while institutional strategies for advancing nanoscale science are summarized at the end.     

Results of Russian/US high-performance DEMG experiment

In November 1992, the All-Russian Scientific Research Institute of Experimental Physics (VNIIEF), Arzamas-16, Russia and the Los Alamos National Laboratory, Los Alamos NM, USA embarked on a historic effort to conduct a joint explosive pulse-power experiment. With the concurrence of the Ministry of Atomic Energy (Russia) and the Department of Energy (US), the two laboratories entered into a laboratory-to-laboratory collaboration in the areas of very high-energy pulse power and ultrahigh magnetic fields in order to explore problems of mutual scientific interest. The first experiment to be planned was an explosively powered, fast, high-current pulse-power system demonstration. The experiment used a flux compressor, inductive store, and high-current opening switch to demonstrate the feasibility of supplying many megajoules of electrical energy, on microsecond time scales, to high-energy density physics experiments. The experiment was conducted in Arzamas-16 on September 22, 1993     

Studies on Performance of Thermoacoustic Prime Mover

Thermoacoustic engines are the devices that convert thermal energy into acoustic energy without moving parts. The main objective of this study is to analyze the performance of a thermoacoustic prime mover measured in terms of onset temperature difference, frequency, and pressure amplitude by varying resonator, stack length, and plate thickness. From the experiments, it is observed that onset temperature difference and pressure amplitude increases with increase in resonator and stack length with minimum plate thickness, whereas the frequency increases with decrease in resonator and stack length with higher plate thickness. The experimental results are compared with simulated results via Design Environment for Low Amplitude Thermoacoustic Energy Conversion software (Los Alamos National Laboratory, Los Alamos, New Mexico, USA).     

A Wavenumber,Intensity, and Resolution Standard for High Resolution Ultraviolet/Visible Fourier Transform Spectroscopy

Abstract

The Re I (527. 55 nm, 18955 cm^?1) emission line from a hollow cathode lamp (HCL) is proposed as a standard for wavenumber accuracy and precision, resolution accuracy and precision and intensity precision. The Los Alamos Fourier transform spectrometer measured the HCL emission at high resolution (0. 026 cm^?1). The advantages of this spectral line to other emission standards is discussed.     

Viktor Trkal,Beltrami fields,and Trkalian flows

A 1919 contribution of Viktor Trkal on Beltrami fields is contextualized and shown to be of significance in fluid mechanics, time-harmonic electromagnetism and astrophysics.This paper introduces the English translation of an article by V. Trkal from 1919 — see next paper in this issue, p. 97.I gratefully acknowledge the assistance of Drs. Per Lindstrom (Bergen, Norway), Avadh B. Saxena (Los Alamos, New Mexico), Chandra S. Vikrarn (Huntsville, Alabama) and Miloslav Znojil (Prague) in locating old publications. I also thank the editors of this journal for asking me to write this introductory piece as well as for readily agreeing to publish an English translation of Trkal's paper.     

A Conversation with Robert F. Christy – Part II

Robert F. Christy, Institute Professor of Theoretical Physics Emeritus at Caltech, recalls his wartime work at Los Alamos on the critical assembly for the plutonium bomb (“the Christy bomb”); the Alamogordo test, July 16, 1945; the postwar concerns of ALAS (Association of Los Alamos Scientists); his brief return to the University of Chicago and move to Caltech; friendship with and later alienation from Edward Teller; work with Charles and Tommy Lauritsen and William A. Fowler in Caltech’s Kellogg Radiation Laboratory; Freeman Dyson’s Orion Project; work on the meson and RR Lyrae stars; fellowship at Cambridge University; 1950s Vista Project at Caltech; his opposition to the Strategic Defense Initiative; and his post-retirement work for the National Research Council’s Committee on Dosimetry and on inertial-confinement fusion.     

Structure analysis of turbulent mixing patterns in inert and reactive turbulent liquid flows

The paper contains an extended summary of an invited plenary talk given at the Workshop on Active Chaos at the Los Alamos National Laboratory on 29-31 May 2001 by one of us (F.S.R.). (c) 2002 American Institute of Physics.     

External noise and its interaction with spatial degrees of freedom in nonlinear dissipative systems

A brief introduction to the field is given together with an overview of the lectures given at the workshop on External Noise and its Interaction with Spatial Degrees of Freedom in Nonlinear Dissipative Systems organized by the Center for Nonlinear Studies at Los Alamos, March 28–31, 1988. It is hoped that the publication of papers presented at the workshop in a single issue of theJournal of Statistical Physics will help draw attention to the recent developments in this rapidly area of nonequilibrium phenomena.     

First Protein Crystallography Experiments on a Synchrotron

My story started in the winter of 1973/1974. I was a graduate student at UCLA, my thesis work was going nowhere, and my wife was expecting a baby in the early summer, while we had no health insurance that would pay for this happy event. It was clearly time to find a place other than Los Angeles to continue work in protein crystallography. Since I wanted to study crystal structure of the nerve growth factor (NGF), and the West Coast expert in that field was Eric Shooter at Stanford, I asked him if he would be willing to accept me as a postdoc. He was, but had no funds. However, somehow he contacted Keith Hodgson and the two of them managed to find some money, to the best of my recollection in the Department of Psychiatry. Although Keith agreed to let me work on the structure of NGF and a few other proteins, he stipulated that my primary objective should be to help in setting up the first in the world beamline devoted to the use of synchrotron radiation for single-crystal diffraction from protein crystals. To tell the truth, I initially had some problems understanding what exactly he had in mind—somehow my undergraduate degree in physics did not cover that particular subject. Thus, in the late spring of 1974, the team was established—Keith at the lead, two postdocs (Margueritte Yevitz Bernheim and myself) and a graduate student, James Phillips. We were joined by Julia Goodfellow (now Dame Julia) a year later. And the Stanford Synchrotron Radiation Project also officially commenced at about the same time.     

Comparison of graphite,aluminum, and TransHab shielding material characteristics in a high-energy neutron field

Space radiation transport models clearly show that low atomic weight materials provide a better shielding protection for interplanetary human missions than high atomic weight materials. These model studies have concentrated on shielding properties against charged particles. A light-weight, inflatable habitat module called TransHab was built and shown to provide adequate protection against micrometeoroid impacts and good shielding properties against charged particle radiation in the International Space Station orbits. An experiment using a tissue equivalent proportional counter, to study the changes in dose and lineal energy spectra with graphite, aluminum, and a TransHab build-up as shielding, was carried out at the Los Alamos Nuclear Science Center neutron facility. It is a continuation of a previous study using regolith and doped polyethylene materials. This paper describes the results and their comparison with the previous study.     

Simulations: A tool for studying quantum condensed matter systems

Quantum Monte Carlo techniques provide a new method for studying the properties of condensed matter systems. A review of this approach and the type of information which it can provide is given. Talk presented at the Frontiers of Monte Carlo Meeting, Los Alamos National Laboratory, September, 1985.     

A four-neutrino mixing scheme for observed neutrino data

It has been observed that simultaneous explanation of the solar and atmospheric neutrino deficits and the reported evidence for oscillation from the Los Alamos Liquid Scintillator Detector (LSND) requires at least one extra neutrino species in addition to the three known ones. The extra neutrino must be sterile with respect to the known weak interactions. We present a new mass matrix for these four neutrinos in which the LSND effect and the atmospheric neutrino deficit are governed by only one parameter. We investigate the phenomenological implications of such a mass matrix ansatz and suggest possible ways to understand it in gauge theories.     

Applications of trapped antiprotons

Recent successes in trapping antiprotons suggest that portable traps can be used in several important applications. Included among these are medicine, laser physics, energy development, and nondestructive materials evaluation. An experimental program for the next three years is outlined.Work supported in part by the AFOSR, Jet Propulsion Laboratory, Los Alamos National Laboratory, and Rocketdyne Corporation.     

高能质子照相中面密度的测量和不确定性分析

 依据洛斯·阿拉莫斯国家实验室的质子照相概念,通过研究高能质子与物质的相互作用规律,给出了质子照相确定面密度的计算公式及其不确定性分析,阐述了质子照相鉴别材料组分的原理。相对于X光照相,质子通过面密度较大的物体后的通量明显增加,界面探测和密度重建更加准确。研究了多库仑散射和磁透镜系统的色散对质子照相空间分辨率的影响及解决途径。结果表明,高能质子照相在穿透能力、面密度测量、材料的组分识别、空间分辨率等方面都优于X光照相。     

A Conversation with Robert F. Christy – Part I

Robert F. Christy, Institute Professor of Theoretical Physics Emeritus at Caltech, recalls his childhood in British Columbia; his undergraduate years at the University of British Columbia; his graduate work with J. Robert Oppenheimer at Berkeley; and his work on the Manhattan Project, first with Enrico Fermi at the Metallurgical Laboratory of the University of Chicago and then as a member of the Theoretical Division at Los Alamos.