Nuclear Physics with 10 PW laser beams at Extreme Light Infrastructure – Nuclear Physics (ELI-NP)

The field of the uncharted territory of high-intensity laser interaction with matter is confronted with new exotic phenomena and, consequently, opens new research perspectives. The intense laser beams interacting with a gas or solid target generate beams of electrons, protons and ions. These beams can induce nuclear reactions. Electrons also generate ions high-energy photons via bremsstrahlung processes which can also induce nuclear reactions. In this context a new research domain began to form in the last decade or so, namely nuclear physics with high power lasers. The observation of high brilliance proton beams of tens of MeV energy from solid targets has stimulated an intense research activity. The laser-driven particle beams have to compete with conventional nuclear accelerator-generated beams. The ultimate goal is aiming at applications of the laser produced beams in research, technology and medicine. The mechanism responsible for ion acceleration are currently subject of intensive research in many laboratories in the world. The existing results, experimental and theoretical, and their perspectives are reviewed in this article in the context of IZEST and the scientific program of ELI-NP.     

Development and Construction of Track and Identification Systems for Experiments Aimed at Studying Extreme Properties of Nuclear Matter in Nucleus–Nucleus Collisions

Physics of Atomic Nuclei - Investigation of properties of nuclear matter at extremely high temperature and/or extremely high baryon densities under laboratory conditions is one of the fundamental...     

Quantum Humor: The Playful Side of Physics at Bohr’s Institute for Theoretical Physics

From the 1930s to the 1950s, a period of pivotal developments in quantum, nuclear, and particle physics, physicists at Niels Bohr??s Institute for Theoretical Physics in Copenhagen took time off from their research to write humorous articles, letters, and other works. Best known is the Blegdamsvej Faust, performed in April 1932 at the close of one of the Institute??s annual conferences. I also focus on the Journal of Jocular Physics, a humorous tribute to Bohr published on the occasions of his 50^th, 60^th, and 70^th birthdays in 1935, 1945, and 1955. Contributors included Léon Rosenfeld, Victor Weisskopf, George Gamow, Oskar Klein, and Hendrik Casimir. I examine their contributions along with letters and other writings to show that they offer a window into some issues in physics at the time, such as the interpretation of complementarity and the nature of the neutrino, as well as the politics of the period.     

Nuclear PDFs at NLO – status report and review of the EPS09 results

We review the current status of the global DGLAP analysis of nuclear parton distribution functions, nPDFs, focusing on the recent EPS09 analysis [K.J. Eskola, H. Paukkunen, C.A. Salgado, JHEP 0904 (2009) 065. [arXiv:0902.4154 [hep-ph]]], whose output, EPS09NLO, is the best-constrained NLO nPDF set on the market. Collinear factorization is found to work very well in the kinematical region studied. With the error sets released in the EPS09 package one can compute how the nPDF-related uncertainties propagate into factorizable nuclear hard-process cross sections. A comparison with the other existing NLO nPDF sets is shown, and the BRAHMS forward-η hadron data from d+Au collisions are discussed in the light of the EPS09 nPDFs and their error sets.     

Fabrication of Ge Nano-Dot Heterojunction Phototransistors for Improved Light Detection at 1.55μm

Heterojunction phototransistors （HPTs） with several Ge/Si nano-dot layers as the absorption region are fabricated to obtain improved light detectivity at 1.55μm. The HPT detectors are of n-p-n type with ten layers of Ge（8ML ） /Si（45nm） incorporated in the base-collector junction and are grown by an ultrahigh-vacuum chemicalvapor-deposition system. The detectors are operated with normal incidence. Because of the good quality of the grown material and fabrication process, the dark current is only 0.71pA/μm^2 under 5 V bias and the breakdown voltage is over 20 V. Compared to the positive-intrinsic-negative （PIN） reference detector with the same absorption layer, the responsivity is improved over 17 times for normal incidence at 1.55μm.     

Photoproduction of heavy vector mesons at HERA – a test field for diffraction

Exclusive diffractive photoproduction of heavy vector mesons (V=, and ) at HERA is studied in a model employing a dipole Pomeron exchange (P) with an inelastic vertex. The model is fitted to the data on , B, and for and beyond the threshold region. The elastic cross sections for both and photoproduction show a moderate increase within the HERA energy region. The flattening of the slope B(s) (indicating little or no shrinkage) for is not correlated with the slope of the Pomeron trajectory. Estimates for photoproduction at HERA are given. Received: 11 January 1999 / Published online: 8 September 1999     

Nuclear data for the cyclotron production of ~（117）Sb and ~（90）Nb

This presented study is to make comparison of cross sections to produce ¹¹⁷Sb and ⁹⁰Nb via different reactions with particle incident energy up to 70 MeV as a part of systematic studies on particle-induced activations on enriched Sn, Y₂O₃ and ZrO₂ targets, theoretical calculation of production yield, calculation of required thickness of target and suggestion of optimum reaction to produce Antimony-117 and Niobium-90.     

Measurement of the production cross section for charmed baryons in proton–nucleus interactions at 70 GeV

The results of an analysis of data from the SERP-Е-184 experiment devoted to studying mechanisms of the production of charmed particles in proton–nucleus interactions at 70 GeV and their decays are presented. The data in question were obtained upon irradiating the SVD-2 active target consisting of carbon, silicon, and lead plates with a beam of 70-GeV protons. A detailed simulation on the basis of the FRITIOF7.02 and GEANT3.21 code packages made it possible to optimize event-selection criteria and to calculate the detection efficiency for Λ_c⁺ baryons. After selecting a signal from the threebody decay of a Λ_c⁺ baryon, the inclusive cross section for its production at near-threshold energies, its lifetime, and the parameter of the A dependence of the cross section were found. The Λ_c⁺ -baryon yields are tabulated along with data from other experiments and theoretical predictions.     

Experimental studies of (n, α) reaction cross-sections performed at the Institute for Physics and Power Engineering

Studies of (n, α) reaction cross-sections on a number of isotopes over a wide range of neutron energies were performed systematically at the Institute for Physics and Power Engineering (IPPE) A new spectrometer that includes an ionization chamber and a pulse shape digitizer were used. The experimental technique and the results of measurements of the reaction cross-sections ¹⁶O(n, α)¹³C, ¹⁴N(n, α)¹¹B, ²⁰Ne(n, α)¹⁷O, ³⁶Ar(n, α)³³S, ⁴⁰Ar(n, α)³⁷S, ¹⁰B(n, α)⁷Li, and ⁵⁰Cr(n, α)⁷Li, are described.     

Search for pair production of second-generation scalar leptoquarks in pp collisions at √s = 7 TeV

A search for pair production of second-generation scalar leptoquarks in the final state with two muons and two jets is performed using proton-proton collision data at √s = 7 TeV collected by the CMS detector at the LHC. The data sample used corresponds to an integrated luminosity of 34 pb?1. The number of observed events is in good agreement with the predictions from the standard model processes. An upper limit is set on the second-generation leptoquark cross section times β2 as a function of the leptoquark mass, and leptoquarks with masses below 394 GeV are excluded at a 95% confidence level for β = 1, where β is the leptoquark branching fraction into a muon and a quark. These limits are the most stringent to date.     

Search for pair production of first-generation scalar leptoquarks in pp collisions at √s = 7 TeV

A search for pair production of first-generation scalar leptoquarks is performed in the final state containing two electrons and two jets using proton-proton collision data at √s = 7 TeV. The data sample used corresponds to an integrated luminosity of 33 pb?1 collected with the CMS detector at the CERN LHC. The number of observed events is in good agreement with the predictions for the standard model background processes, and an upper limit is set on the leptoquark pair production cross section times β2 as a function of the leptoquark mass, where β is the branching fraction of the leptoquark decay to an electron and a quark. A 95% confidence level lower limit is set on the mass of a first-generation scalar leptoquark at 384 GeV for β = 1, which is the most stringent direct limit to date.     

Measurement of A LL and cross section of high p T charged π meson production for constraining ΔG at PHENIX

PHENIX at RHIC measured invariant differential cross section and double helicity asymmetry A _LL of high p _T charged pions production in polarized p + p collision at √s = 200 GeV. Interpretations of preliminary results regarding constraining gluon helicity distribution are discussed.     

Review of searches for Higgs bosons and beyond the Standard Model Physics at the Tevatron

The energy frontier is currently at the Fermilab Tevatron accelerator, which collides protons and antiprotons at a center-of-mass energy of 1.96 TeV. The luminosity delivered to the CDF and DØ experiments has now surpassed the 4 fb^?1. This paper reviews the most recent direct searches for Higgs bosons and beyond-the-standard-model (BSM) physics at the Tevatron. The results reported correspond to an integrated luminosity of up to 2.5 fb^?1 of Run II data collected by the two Collaborations. Searches covered include the standard model (SM) Higgs boson (including sensitivity projections), the neutral Higgs bosons in the minimal supersymmetric extension of the standard model (MSSM), charged Higgs bosons and extended Higgs models, supersymmetric decays that conserve or violate R-parity, gauge-mediated supersymmetric breaking models, long-lived particles, leptoquarks, compositeness, extra gauge bosons, extra dimensions, and finally signature-based searches. Given the excellent performance of the collider and the continued productivity of the experiments, the Tevatron physics potential looks promising for discovery with the coming larger data sets. In particular, evidence for the SM Higgs boson could be obtained if its mass is light or near 160 GeV. The observed (expected) upper limits are currently a factor of 3.7 (3.3) higher than the expected SM Higgs boson cross section at m _H =115 GeV and 1.1 (1.6) at m _H =160 GeV at 95% C.L.     

Excitation of high-spin nuclear isomeric states by intermediate energy protons at the Moscow Meson Factory of the Russian Academy of Sciences’ Institute for Nuclear Research

Isomeric ratios of reaction products obtained by irradiating ¹⁹⁷Au, ¹⁸¹Ta, and ⁹³Nb targets by protons with energies of 143?C325 MeV are measured via activation. The results do not agree with measurements of stopped ions [1], even though the theoretical model in [2] predicted the same mechanism for the formation of high-spin isomers in these reactions. The obtained isomeric ratios in reactions with protons of intermediate energy are 10?C100 times lower than the theoretical values; consequently, the excitation mechanisms of high-spin isomers in reactions with protons and stopped ions are different.     

Optimization of hydrostatic pressure at varied sonication conditions – power density,intensity, very low frequency – for isothermal ultrasonic sludge treatment

This work aims at investigating for the first time the key sonication (US) parameters: power density (D_US), intensity (I_US), and frequency (F_S) – down to audible range, under varied hydrostatic pressure (P_h) and low temperature isothermal conditions (to avoid any thermal effect).The selected application was activated sludge disintegration, a major industrial US process. For a rational approach all comparisons were made at same specific energy input (ES, US energy per solid weight) which is also the relevant economic criterion.The decoupling of power density and intensity was obtained by either changing the sludge volume or most often by changing probe diameter, all other characteristics being unchanged. Comprehensive results were obtained by varying the hydrostatic pressure at given power density and intensity. In all cases marked maxima of sludge disintegration appeared at optimum pressures, which values increased at increasing power intensity and density. Such optimum was expected due to opposite effects of increasing hydrostatic pressure: higher cavitation threshold then smaller and fewer bubbles, but higher temperature and pressure at the end of collapse.In addition the first attempt to lower US frequency down to audible range was very successful: at any operation condition (D_US, I_US, P_h, sludge concentration and type) higher sludge disintegration was obtained at 12 kHz than at 20 kHz. The same values of optimum pressure were observed at 12 and 20 kHz.At same energy consumption the best conditions – obtained at 12 kHz, maximum power density 720 W/L and 3.25 bar – provided about 100% improvement with respect to usual conditions (1 bar, 20 kHz). Important energy savings and equipment size reduction may then be expected.     

Observation of ammonia dihydrate in the AMH-VI structure at room temperature – possible implications for the outer solar system

Ammonia dihydrate (ADH) is an important constituent of the outer solar system and its high-pressure behaviour is relevant to the modelling of Titan, Uranus and Neptune. Our neutron diffraction studies show that ADH can exist at room temperature in the substitutionally disordered structure of the ammonia monohydrate (AMH) phase VI. This implies that a solid solution may exist between ADH and AMH at high pressure, and this is of probable importance to models of the outer solar system.