117126887
A Search for Double Parton Interactions in 1.8-TeV Proton - Anti-Proton Collisions
17140866
Extracting longitudinal shower development information from crystal calorimetry plus tracking
arXiv:0711.1593v2 [physics.ins-det] 11 Apr 2008 Extracting longitudinal shower development information from crystal calorimetry plus tracking D.N. Brown a , J. Ilic b , G.B. Mohanty b a Lawrence b Department Berkeley National Laboratory, Berkeley, California 94720, USA of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom Abstract We present an approach to derive longitudinal shower development information from the longitudinally unsegmented B A B AR electromagnetic calorimeter by using tracking information. Our algorithm takes advantage of the good three- dimensional tracking resolution of B A B AR , which provides an independent geometric constraint on the shower as measured in the B A B AR crystal calorimeter. We show that adding the derived longitudinal shower development information to standard particle identiﬁcation algorithms signiﬁcantly improves the low-momentum separation of pions from electrons and muons. We also verify that the energy dependence of the electromagnetic shower development we measure is consistent with the prediction of a standard electromagnetic shower model. Key words: Particle Identiﬁcation, Longitudinal Shower Depth, Electromagnetic Calorimetry, Tracking PACS: 29.40.Gx, 29.40.Vj, 07.05.Kf 1. Introduction In present-day nuclear and particle physics ex- periments, inorganic scintillating crystals, such as NaI(Tl) and CsI(Tl), are often used to construct electromagnetic calorimeters when a precise mea- surement of the energy is required [1]. Crystal calorimeters can be ﬁnely segmented in the dimen- sion transverse to the shower development without sacriﬁcing energy resolution, thus providing a good measurement of the lateral shower development. However, engineering and energy resolution consid- erations prevent ﬁnely segmenting crystal calorime- ters along the direction of shower development. Both lateral and longitudinal shower development information are useful in charged particle identi- Email addresses: Dave Brown@lbl.gov (D.N. Brown), J.Ilic@warwick.ac.uk (J. Ilic), G.B.Mohanty@warwick.ac.uk (G.B. Mohanty). Preprint submitted to Elsevier Science ﬁcation (PID) algorithms, particularly in electron identiﬁcation. Because crystal calorimeters cannot provide direct longitudinal shower development in- formation, they lose an important input to particle identiﬁcation. In this paper, we present a technique in which longitudinal shower development information is indirectly extracted from a longitudinally unseg- mented crystal calorimeter in conjunction with a precise tracking system. This technique was devel- oped for use with the B A B AR [2] detector, but it can be applied at any detector which combines crystal calorimetry and precision tracking. It exploits the fact that B A B AR has a tracking system capable of precisely determining the three-dimensional trajec- tory of charged particles, and the fact that these trajectories are not in general collinear with the crystal axes. A similar algorithm has previously been used for sampling calorimeters with ﬁne lateral segmentation [3]. 11 April 2008
110445306
The distributed production system of the SuperB project: description and results
The SuperB experiment needs large samples of MonteCarlo simulated events in order to finalize the detector design and to estimate the data analysis performances. The requirements are beyond the capabilities of a single computing farm, so a distributed production model capable of exploiting the existing HEP worldwide distributed computing infrastructure is needed. In this paper we describe the set of tools that have been developed to manage the production of the required simulated events. The production of events follows three main phases: distribution of input data files to the remote site Storage Elements (SE); job submission, via SuperB GANGA interface, to all available remote sites; output files transfer to CNAF repository. The job workflow includes procedures for consistency checking, monitoring, data handling and bookkeeping. A replication mechanism allows storing the job output on the local site SE. Results from 2010 official productions are reported.
61201473
GLOBAL VDET PATTERN RECOGNITION FOR ALEPH
With the current reliance on high-precision vertex detectors to provide very accurate information about the primary and secondary vertices in an event, the accuracy and ee-ciency of the assignment of vertex detector hits to tracks has become crucial. This paper discusses new software written for ALEPH which attempts to make this assignment in a global manner using integer programming techniques.
115714674
BaBar results on sin(2beta) and B0 oscillations
124844326
Observation of the Rare Decay B^+ to K^+ \pi^0 \pi^0
We report an analysis of charmless hadronic decays of charged B mesons to the final state K{sup +}{pi}{sup 0}{pi}{sup 0}, using a data sample of 470.9 {+-} 2.8 million B{bar B} events collected with the BABAR detector at the {Upsilon}(4S) resonance. We observe an excess of signal events with a significance above 10 standard deviations including systematic uncertainties and measure the branching fraction to be {Beta}(B{sup +}{yields}K{sup +}{pi}{sup 0}{pi}{sup 0}) = (15.5 {+-} 1.1 {+-} 1.6) x 10{sup -6}, where the uncertainties are statistical and systematic, respectively.
2754505
Using the inspiral program to search for gravitational waves from low-mass binary inspiral
The INSPIRAL program is the LIGO Scientific Collaboration's computational engine for the search for gravitational waves from binary neutron stars and sub-solar mass black holes. We describe how this program, which makes use of the FINDCHIRP algorithm, is integrated into a sophisticated data analysis pipeline that was used in the search for low-mass binary inspirals in data taken during the second LIGO science run.
2256332
Report on the second Mock LISA data challenge
The Mock LISA data challenges are a program to demonstrate LISA data-analysis capabilities and to encourage their development. Each round of challenges consists of several data sets containing simulated instrument noise and gravitational waves from sources of undisclosed parameters. Participants are asked to analyze the data sets and report the maximum information about the source parameters. The challenges are being released in rounds of increasing complexity and realism: here we present the results of Challenge 2, issued in Jan 2007, which successfully demonstrated the recovery of signals from nonspinning supermassive-black-hole binaries with optimal SNRs between ~10 and 2000, from ~20 000 overlapping galactic white-dwarf binaries (among a realistically distributed population of 26 million), and from the extreme-mass-ratio inspirals of compact objects into central galactic black holes with optimal SNRs ~100.
55819607
Detecting binary neutron star systems with spin in advanced gravitational-wave detectors
The detection of gravitational waves from binary neutron stars is a major goal of the gravitational-wave observatories Advanced LIGO and Advanced Virgo. Previous searches for binary neutron stars with LIGO and Virgo neglected the component stars' angular momentum (spin). We demonstrate that neglecting spin in matched-filter searches causes advanced detectors to lose more than 3% of the possible signal-to-noise ratio for 59% (6%) of sources, assuming that neutron star dimensionless spins, $c\mathbf{J}/GM^2$, are uniformly distributed with magnitudes between 0 and 0.4 (0.05) and that the neutron stars have isotropically distributed spin orientations. We present a new method for constructing template banks for gravitational wave searches for systems with spin. We present a new metric in a parameter space in which the template placement metric is globally flat. This new method can create template banks of signals with non-zero spins that are (anti-)aligned with the orbital angular momentum. We show that this search loses more than 3% of the maximium signal-to-noise for only 9% (0.2%) of BNS sources with dimensionless spins between 0 and 0.4 (0.05) and isotropic spin orientations. Use of this template bank will prevent selection bias in gravitational-wave searches and allow a more accurate exploration of the distribution of spins in binary neutron stars.
8628997
Searching for gravitational waves from binary inspirals with LIGO
We describe the current status of the search for gravitational waves from inspiralling compact binary systems in LIGO data. We review the result from the first scientific run of LIGO (S1). We present the goals of the search of data taken in the second scientific run (S2) and describe the differences between the methods used in S1 and S2.
122902661
Inelastic alpha scattering studies of the low-energy octupole resonance
Beams of 96 and 115 MeV $\ensuremath{\alpha}$ particles have been used to study the distribution of isoscalar octupole strength in 18 nuclei from $^{40}\mathrm{Ca}$ to $^{208}\mathrm{Pb}$. A prominent broad peak ($\ensuremath{\Gamma}\ensuremath{\sim}2.5$ MeV) is observed at ${E}_{x}\ensuremath{\sim}\frac{30}{{A}^{\frac{1}{3}}}$ MeV in nuclei from $^{66}\mathrm{Zn}$ to $^{197}\mathrm{Au}$. No broad peak is observed in this excitation energy range in $^{208}\mathrm{Pb}$ or $^{40}\mathrm{Ca}$ and lighter nuclei. The oscillatory angular distributions of the ($\ensuremath{\alpha}, {\ensuremath{\alpha}}^{\ensuremath{'}}$) reaction exciting this peak are in excellent agreement with $l=3$ distorted-wave Born approximation calculations. Studies of the angular range from ${\ensuremath{\sigma}}_{\mathrm{lab}}=3.5\ifmmode^\circ\else\textdegree\fi{} \mathrm{to} 6\ifmmode^\circ\else\textdegree\fi{}$ in $^{116}\mathrm{Sn}$ indicate very little contribution from $l=1$ strength. Energy- weighted sum rule fractions for this low-energy octupole resonance are generally in the range from 15% to 20%; this corresponds to \textonehalf{} to $\frac{2}{3}$ of the expected $1\ensuremath{\hbar}\ensuremath{\omega}$ octupole strength. The overall distribution of octupole strength in spherical nuclei, including the absence of the low-energy octupole resonance in $^{40}\mathrm{Ca}$ and $^{208}\mathrm{Pb}$, is in very good agreement with random-phase approximation calculations. The low-energy octupole resonance undergoes a pronounced change in structure in soft-vibrational and deformed nuclei. Theoretical calculations for the low-energy octupole resonance in $^{154}\mathrm{Sm}$ account qualitatively for the data.