Search for Gravitational Waves from Primordial Black Hole Binary Coalescences in the Galactic Halo

We use data from the second science run of the LIGO gravitational-wave detectors to search for the gravitational waves from primordial black hole (PBH) binary coalescence with component masses in the range 0.2--$1.0 M_\odot$. The analysis requires a signal to be found in the data from both LIGO observatories, according to a set of coincidence criteria. No inspiral signals were found. Assuming a spherical halo with core radius 5 kpc extending to 50 kpc containing non-spinning black holes with masses in the range 0.2--$1.0 M_\odot$, we place an observational upper limit on the rate of PBH coalescence of 63 per year per Milky Way halo (MWH) with 90% confidence.Comment: 7 pages, 4 figures, to be submitted to Phys. Rev.

All-sky search for gravitational-wave bursts in the second joint LIGO-Virgo run

We present results from a search for gravitational-wave bursts in the data collected by the LIGO and Virgo detectors between July 7, 2009 and October 20, 2010: data are analyzed when at least two of the three LIGO-Virgo detectors are in coincident operation, with a total observation time of 207 days. The analysis searches for transients of duration < 1 s over the frequency band 64-5000 Hz, without other assumptions on the signal waveform, polarization, direction or occurrence time. All identified events are consistent with the expected accidental background. We set frequentist upper limits on the rate of gravitational-wave bursts by combining this search with the previous LIGO-Virgo search on the data collected between November 2005 and October 2007. The upper limit on the rate of strong gravitational-wave bursts at the Earth is 1.3 events per year at 90% confidence. We also present upper limits on source rate density per year and Mpc^3 for sample populations of standard-candle sources. As in the previous joint run, typical sensitivities of the search in terms of the root-sum-squared strain amplitude for these waveforms lie in the range 5 10^-22 Hz^-1/2 to 1 10^-20 Hz^-1/2. The combination of the two joint runs entails the most sensitive all-sky search for generic gravitational-wave bursts and synthesizes the results achieved by the initial generation of interferometric detectors.Comment: 15 pages, 7 figures: data for plots and archived public version at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=70814&version=19, see also the public announcement at http://www.ligo.org/science/Publication-S6BurstAllSky

Hyperfine field of einsteinium in iron and nuclear magnetic moment of 254Es

The angular distributions of γ rays and α particles from oriented 250Bk, 253,254Es, and 255Fm nuclei were investigated to extract hyperfine interaction information for these actinide impurities in an iron host lattice. The hyperfine field of einsteinium in iron was found to be |Bhf (EsFe|) = 396(32) T. With this value the magnetic moment of 254Es was then determined as |μ| = 4.35(41) μN.status: publishe

Measurement of the diffractive cross-section in deep inelastic scattering

Diffractive scattering of $\gamma^* p \to X + N$, where $N$ is either a proton or a nucleonic system with $M_N~<~4$~GeV has been measured in deep inelastic scattering (DIS) at HERA. The cross section was determined by a novel method as a function of the $\gamma^* p$ c.m. energy $W$ between 60 and 245~GeV and of the mass $M_X$ of the system $X$ up to 15~GeV at average $Q^2$ values of 14 and 31~GeV$^2$. The diffractive cross section $d\sigma^{diff} /dM_X$ is, within errors, found to rise linearly with $W$. Parameterizing the $W$ dependence by the form d\sigma^{diff}/dM_X \propto (W^2)^{(2\overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} -2)} the DIS data yield for the pomeron trajectory \overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} = 1.23 \pm 0.02(stat) \pm 0.04 (syst) averaged over $t$ in the measured kinematic range assuming the longitudinal photon contribution to be zero. This value for the pomeron trajectory is substantially larger than \overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} extracted from soft interactions. The value of \overline{\mbox{\alpha_{_{I\hspace{-0.2em}P}}}} measured in this analysis suggests that a substantial part of the diffractive DIS cross section originates from processes which can be described by perturbative QCD. From the measured diffractive cross sections the diffractive structure function of the proton F^{D(3)}_2(\beta,Q^2, \mbox{x_{_{I\hspace{-0.2em}P}}}) has been determined, where $\beta$ is the momentum fraction of the struck quark in the pomeron. The form F^{D(3)}_2 = constant \cdot (1/ \mbox{x_{_{I\hspace{-0.2em}P}}})^a gives a good fit to the data in all $\beta$ and $Q^2$ intervals with $a = 1.46 \pm 0.04 (stat) \pmComment: 45 pages, including 16 figure

Measurement of elastic phi photoproduction at HERA

The production of phi mesons in the reaction e(+)p --> e(+)phi p (phi --> K+K-) at a median Q(2) of 10(-4) GeV2 has been studied with the ZEUS detector at HERA. The differential phi photoproduction cross section d sigma/dt has an exponential shape and has been determined in the kinematic range 0.1 phi p) = 0.96+/-0.19(-0.18)(+0.21) mu b has been obtained by extrapolating to t = 0. When compared to lower energy data, the results show a weak energy dependence of both sigma(gamma-->phi p) and the slope of the t distribution. The phi decay angular distributions are consistent with s-channel helicity conservation. From lower energies to HERA energies, the features of phi photoproduction are compatible with those of a soft diffractive process

MEASUREMENT OF THE DIFFRACTIVE STRUCTURE-FUNCTION IN DEEP-INELASTIC SCATTERING AT HERA RID B-9165-2008 RID C-5889-2009 RID A-4818-2008 RID C-1693-2008

This paper presents an analysis of the inclusive properties of diffractive deep inelastic scattering events produced in ep interactions at HERA. The events are characterised by a rapidity gap between the outgoing proton system and the remaining hadronic system. Inclusive distributions are presented and compared with Monte Carlo models for diffractive processes. The data are consistent with models where the pomeron structure function has a hard and a soft contribution. The diffractive structure function is measured as a function of x(p), the momentum fraction lost by the proton, of beta, the momentum fraction of the struck quark with respect to x(p), and of Q(2) in the range 6.3 10(-4) < x(p) < 10(-2), 0.1 < .beta < 0.8 and 8 < Q(2) < 100 GeV2. The x(p) dependence is consistent with the form (1/x(p))(alpha) where alpha = 1.30 +/- 0.08 (stat)(-0.14)(+0.08) (sys) in all bins of beta and Q(2). In the measured Q(2) range, the diffractive structure function approximately scales with Q(2) at fixed beta. In an Ingelman-Schlein type model where commonly used pomeron flux factor normalisations are assumed, it is found that the quarks within the pomeron do not saturate the momentum sum rule

Study of charged-current ep interactions at Q(2)&gt;200 GeV2 with the ZEUS detector at HERA

Deep inelastic charged-current reactions have been studied in e+p and e-p collisions at a center of mass energy of about 300GeV in the kinematic region Q2&gt;200GeV2 and x&gt;0.006 using the ZEUS detector at HERA. The integrated cross sections for Q2&gt;200GeV2 are found to be {Mathematical expression} and {Mathematical expression}. Differential cross sections have been measured as functions of the variables x, y and Q2. From the measured differential cross sections dσ/dQ2, the W boson mass is determined to be {Mathematical expression}. Measured jet rates and transverse energy profiles agree with model predictions. A search for charged-current interactions with a large rapidity gap yielded one candidate event, corresponding to a cross section of {Mathematical expression} © 1996 Springer-Verlag