P. Lebrun

A wide band photon beam at the Fermilab Tevatron to study heavy flavors

13 Present address: Vector Research Company, 6903 Rockledge Drive, Bethesda, MD 20817, USA . Present address : University of North Carolina-Asheville, Asheville, NC 28804, USA . Present address: STX Inc., 4400 Forbes Blvd ., Lanham, MD 20706, USA . Present address : University of Colorado, Boulder, CO 80309, USA . Present address : Fermilab, Batavia, IL 60510, USA. Present address : Dipartimento di Elettronica, University dl Pavia, Pavia, Italy. Present address : Dipartimento di Fisica Nucleate e Teorica dellUniversita and INFN Pavia, 1-27100 Pavia, Italy Present address : State University of New York, Stony Brook, NY 11794, USA. Present address : NIKHEF-H, 1009 DB, Amsterdam, The Netherlands . Present address : University of Alabama, Tuscaloosa, AL 35487, USA . Present address : Brandeis University, Waltham, MA 02254, USA. Present address : University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. Present address : Nevis Labs, Columbia University, Irvington, NY 10533, USA.

A measurement of elastic J/ψ photoproduction cross section at Fermilab E687☆

Abstract Measurements of elastic photoproduction cross sections for the J / ψ meson from 100 GeV to 375 GeV are presented. The results indicate that the cross section increases slowly in this range. The shape of the energy dependence agrees well with the photon-gluon fusion model prediction.

Background rejection in NEXT using deep neural networks

We investigate the potential of using deep learning techniques to reject background events in searches for neutrinoless double beta decay with high pressure xenon time projection chambers capable of detailed track reconstruction. The differences in the topological signatures of background and signal events can be learned by deep neural networks via training over many thousands of events. These networks can then be used to classify further events as signal or background, providing an additional background rejection factor at an acceptable loss of efficiency. The networks trained in this study performed better than previous methods developed based on the use of the same topological signatures by a factor of 1.2 to 1.6, and there is potential for further improvement.

Study of charged hadronic four-body decays of the D0 meson

Abstract Charged hadronic four-body decays of D 0 mesons have been studied in the E687 photoproduction experiment at Fermilab. Branching ratios relative to the D 0 → K − π + π + π − decay mode for the Cabibbo-suppressed decays D 0 → π − π + π − π + , D 0 → K − K + π − π + have been measured and the first evidence of the D 0 → K − K + K − π + decay mode is reported. An analysis of the D 0 → K − K + π − π + resonance structure is also presented.

Studies of DD correlations in high energy photoproduction

Abstract Analysis of data from the Fermilab high energy photoproduction experiment E687 for events containing fully and partially reconstructed pairs of charmed mesons is presented. Correlations from D D pairs are used to study production dynamics.

Precise measurements of the D0 and D+ meson lifetimes

Abstract We report precise measurements of the D 0 and D + meson lifetimes by the E687 Collaboration at Fermilab. The measurements have been made using 16000 fully reconstructed decays of the D 0 into the K − π + and K − π + π − π + final states and 9000 decays of the D + into the K − π + π + final state. The lifetimes of the D 0 and D + mesons are measured to be 0.413±0.004±0.003 ps and 1.048±0.015±01011 ps respectively.

Application and performance of an ML-EM algorithm in NEXT

The goal of the NEXT experiment is the observation of neutrinoless double beta decay in 136Xe using a gaseous xenon TPC with electroluminescent amplification and specialized photodetector arrays for calorimetry and tracking. The NEXT Collaboration is exploring a number of reconstruction algorithms to exploit the full potential of the detector. This paper describes one of them: the Maximum Likelihood Expectation Maximization (ML-EM) method, a generic iterative algorithm to find maximum-likelihood estimates of parameters that has been applied to solve many different types of complex inverse problems. In particular, we discuss a bi-dimensional version of the method in which the photosensor signals integrated over time are used to reconstruct a transverse projection of the event. First results show that, when applied to detector simulation data, the algorithm achieves nearly optimal energy resolution (better than 0.5% FWHM at the Q value of 136Xe) for events distributed over the full active volume of the TPC.

Comparison of tracking codes for the International Linear Collider

In an effort to compare beam dynamics and create a benchmark for Dispersion Free Steering (DFS) a comparison was made between different International Linear Collider (ILC) simulation programs while performing DFS. This study consisted of three parts. Firstly, a simple betatron oscillation was tracked through each code. Secondly, a set of component misalignments and corrector settings generated from one program was read into the others to confirm similar emittance dilution. Thirdly, given the same set of component misalignments, DFS was performed independently in each program and the resulting emittance dilution was compared. Performance was found to agree exceptionally well in all three studies.

Search for the decay of D+ and Ds+ mesons to three charged kaons

Abstract We report the results of a search for the doubly Cabibbo suppressed decays D+ → K+K−K+ and D+ → ΦK+, and the singly Cabibbo suppressed decays Ds+ → K+K−K+ and Ds+ → ΦK+. Our measurements are all consistent with zero branching ratio, and we set 90% confidence level upper limits on the relative D+ branching ratios: BR(ΦK + ) BR(Φπ + ) , BR(K + K − K + ) BR(Φπ + ) and BR(K + K − K + ) BR(K − π + π + ) , and the relative Ds+ branching ratios: BR(ΦK + ) BR(Φπ + ) and BR(K + K − K + ) BR(Φπ + ) . The data were accumulated by the Fermilab high energy photoproduction experiment E687.

Microscopic simulation of xenon-based optical TPCs in the presence of molecular additives

Abstract We introduce a simulation framework for the transport of high and low energy electrons in xenon-based optical time projection chambers (OTPCs). The simulation relies on elementary cross sections (electron–atom and electron–molecule) and incorporates, in order to compute the gas scintillation, the reaction/quenching rates (atom–atom and atom–molecule) of the first 41 excited states of xenon and the relevant associated excimers, together with their radiative cascade. The results compare positively with observations made in pure xenon and its mixtures with CO 2 and CF 4 in a range of pressures from 0.1 to 10xa0bar. This work sheds some light on the elementary processes responsible for the primary and secondary xenon-scintillation mechanisms in the presence of additives, that are of interest to the OTPC technology.