Underground science initiatives at Los Alamos

Summary Recently, the Los Alamos National Laboratory has proposed two major new initiatives in underground science. Following the dissolution of the original gallium solar-neutrino collaboration, Los Alamos has formed a new North American collaboration. We briefly review the rationale for solar-neutrino research, outline the proposal and new Monte Carlo simulations, and describe the candidate locations for the experiment. Because there is no deep underground site in North America suitable for a dedicated permanent laboratory, Los Alamos has conducted a survey of possible sites and developed a proposal to create a new National Underground Science Facility. This paper also reviews that proposal.

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Riassunto Recentemente il laboratorio nazionale di Los Alamos ha proposto due iniziative fondamentali nella scienza sotterranea. Dopo lo scioglimento dell'originaria collaborazione dei neutrini solari del gallio, Los Alamos ha formato una nuova collaborazione nordamericana. Si esaminano brevemente i fondamenti della ricerca sui neutrini solari, si delineano gli obbiettivi e le nuove simulazioni di Monte Carlo, e si descrivono le località scelte per l'esperimento. Poichè non c'è un posto situato a grande profondità nell'America del nord per un laboratorio permanente dedicato, Los Alamos ha eseguito una ricerca dei luoghi possibili ed ha messo a punto una proposta per creare una nuova National Underground Science Facility. In questo lavoro si esamina questa proposta.

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Резюме Недавно в Национальной лаборатории в Лос Аламосе были предложены два больших новых проекта подземых исседований. После коллаборации по исследованию взаимодействия солнечных нейтрино с галлием, Лос Аламос организовал новую Северо-Американскую коллаборацию. В работе предлагается обзор по поиску солнечных нейтрино, описываются предложения и новые моделирования по методу Монте Карло. Предлагаются возможные нандидаты для местонахождения эксперимента. Так как в Северной Америке не существует глубоко под землей специалвной постоянной лаборатории, то Лас Аламос провел обследование возможных местоположений и разработал проект по созданию новой Национальной лаборатории подземных исследований. Предлагается обзор этого проекта.

     

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.     

SEDs at Los Alamos: A Personal Memoir

I have written this personal memoir approximately 55 years after the events I describe. It is based almost exclusively on memory, since apart from the diary I kept while on Tinian, I have few documents concerning it. It covers my service in the U.S. Army's Special Engineering Detachment (SED) in Oak Ridge and Los Alamos in 1944-45, on Tinian island, the launching pad for the bombing raids on Japan, in the summer and fall of 1945, and my return to Los Alamos until my discharge in January 1946.     

Safety aspects of laser fusion research at the Los Alamos Scientific Laboratory

In 1972, the Los Alamos Scientific Laboratory initiated an organized effort — by forming a Laser Research and Technology Division — to investigate the practicability of using the energy in focused laser beams to confine fusion targets of deuterium for themonuclear burn and subsequent extraction of heat for generating electricity. Criteria for evaluating hazards in high energy laser environments were only in formative stages, and many associated hazards were not contemplated. Fundamental biological data for fast-pulsed lasers was also lacking. This paper describes the control measures instituted and eye-wear developed for the protection of employees. Results of threshold damage experiments are summarized and a programme designed for comprehensive control of the hazards is outlined. To date no biological damage has been experienced by any employee.     

Quasiclassical Born–Oppenheimer Approximations

We discuss several problems in quasiclassical physics for which approximate solutions were recently obtained by a new method, and which can also be solved by novel versions of the Born–Oppenheimer approximation. These cases include the so-called bouncing ball modes, low angular momentum states in perturbed circular billiards, resonant states in perturbed rectangular billiards, and whispering gallery modes. Some rare, special eigenstates, concentrated close to the edge or along a diagonal of a nearly rectangular billiard are found. This kind of state has apparently previously escaped notice.     

J. Robert Oppenheimer: Brilliance and Charisma

No Abstract.  .     

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.     

Dynamics of Rabi model under second-order Born Oppenheimer approximation

We apply the second-order Born–Oppenheimer(BO)approximation to investigate the dynamics of the Rabi model,which describes the interaction between a two-level system and a single bosonic mode beyond the rotating wave approximation.By comparing with the numerical results,we find that our approach works well when the frequency of the two-level system is much smaller than that of the bosonic mode.     

Coulomb—Born—Oppenheimer approximation in Ps—H scattering

To improve the Coulomb-Born approximation (CBA) theory of ionization in positronium (Ps) and atom scattering, the effect of exchange is introduced. The nine-dimensional exchange amplitude for ionization of Ps in Ps—H scattering is reduced to a two-dimensional integral using the present Coulomb-Born-Oppenheimer approximation (CBOA). The methodology is extremely useful to evaluate ionization parameters for different target systems and for different types of ionization processes. It is then applied to evaluate the Ps-ionization cross-section and to estimate the effect of exchange on Psionization in Ps-H system. We establish the importance of exchange at lower energy region.