91 research outputs found
Parametric X-Ray detection in UA9 experiment
Parametric X-Ray radiation (PXR) is a phenomenon due to the interaction of charged particles inside a crystal well ordered lattice. The passage of the particles inside the potential field into the crystal causes small deflections which result in radiation emissions. By this way the emission is diffracted by the crystal planes. In this work the results of the last five years of activity on PXR detection during UA9 experiment are reported. The beam provided in H8 area, protons or Pb ions, is channeled inside different crystals and PXR emission is detected
A prototype large-angle photon veto detector for the P326 experiment at CERN
The P326 experiment at the CERN SPS has been proposed with the purpose of
measuring the branching ratio for the decay K^+ \to \pi^+ \nu \bar{\nu} to
within 10%. The photon veto system must provide a rejection factor of 10^8 for
\pi^0 decays. We have explored two designs for the large-angle veto detectors,
one based on scintillating tiles and the other using scintillating fibers. We
have constructed a prototype module based on the fiber solution and evaluated
its performance using low-energy electron beams from the Frascati Beam-Test
Facility. For comparison, we have also tested a tile prototype constructed for
the CKM experiment, as well as lead-glass modules from the OPAL electromagnetic
barrel calorimeter. We present results on the linearity, energy resolution, and
time resolution obtained with the fiber prototype, and compare the detection
efficiency for electrons obtained with all three instruments.Comment: 8 pages, 9 figures, 2 tables. Presented at the 2007 IEEE Nuclear
Science Symposium, Honolulu HI, USA, 28 October - 3 November 200
Characterization and Performance of PADME's Cherenkov-Based Small-Angle Calorimeter
The PADME experiment, at the Laboratori Nazionali di Frascati (LNF), in
Italy, will search for invisible decays of the hypothetical dark photon via the
process , where the escapes detection. The
dark photon mass range sensitivity in a first phase will be 1 to 24 MeV. We
report here on measurement and simulation studies of the performance of the
Small-Angle Calorimeter, a component of PADME's detector dedicated to rejecting
2- and 3-gamma backgrounds. The crucial requirement is a timing resolution of
less than 200 ps, which is satisfied by the choice of PbF crystals and the
newly released Hamamatsu R13478UV photomultiplier tubes (PMTs). We find a
timing resolution of 81 ps (with double-peak separation resolution of 1.8 ns)
and a single-crystal energy resolution of 5.7%/ with light yield of
2.07 photo-electrons per MeV, using 100 to 400 MeV electrons at the Beam Test
Facility of LNF. We also propose the investigation of a two-PMT solution
coupled to a single PbF crystal for higher-energy applications, which has
potentially attractive features.Comment: 12 pages, 19 figures. v2: added section on radiation damage studie
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Recent Population Size, Trends, and Limiting Factors for the Double-Crested Cormorant in Western North America
The status of the double-crested cormorant (Phalacrocorax auritus) in western North America was last evaluated during 1987–2003. In the interim, concern has grown over the potential impact of predation by double-crested cormorants on juvenile salmonids (Oncorhynchus spp.), particularly in the Columbia Basin and along the Pacific coast where some salmonids are listed for protection under the United States Endangered Species Act. Recent re-evaluations of double-crested cormorant management at the local, flyway, and federal level warrant further examination of the current population size and trends in western North America. We collected colony size data for the western population (British Columbia, Washington, Oregon, Idaho, California, Nevada, Utah, Arizona, and the portions of Montana, Wyoming, Colorado and New Mexico west of the Continental Divide) by conducting aircraft-, boat-, or ground-based surveys and by cooperating with government agencies, universities, and non-profit organizations. In 2009, we estimated approximately 31,200 breeding pairs in the western population. We estimated that cormorant numbers in the Pacific Region (British Columbia, Washington, Oregon, and California) increased 72% from 1987–1992 to circa 2009. Based on the best available data for this period, the average annual growth rate (λ) of the number of breeding birds in the Pacific Region was 1.03, versus 1.07 for the population east of the Continental Divide during recent decades. Most of the increase in the Pacific Region can be attributed to an increase in the size of the nesting colony on East Sand Island in the Columbia River estuary, which accounts for about 39% of all breeding pairs in the western population and is the largest known breeding colony for the species (12,087 breeding pairs estimated in 2009). In contrast, numbers of breeding pairs estimated in coastal British Columbia and Washington have declined by approximately 66% during this same period. Disturbance at breeding colonies by bald eagles (Haliaeetus leucocephalus) and humans are likely limiting factors on the growth of the western population at present. Because of differences in biology and management, the western population of double-crested cormorants warrants consideration as a separate management unit from the population east of the Continental Divide.Keywords: Population, Phalacrocorax auritus, Pacific coast, Cormorant, Limiting factors, Status assessmen
Prospects for at CERN in NA62
The NA62 experiment will begin taking data in 2015. Its primary purpose is a
10% measurement of the branching ratio of the ultrarare kaon decay , using the decay in flight of kaons in an unseparated
beam with momentum 75 GeV/c.The detector and analysis technique are described
here.Comment: 8 pages for proceedings of 50 Years of CP
Characterisation and performance of the PADME electromagnetic calorimeter
The PADME experiment at the LNF Beam Test Facility searches for dark photons produced in the annihilation of positrons with the electrons of a fixed target. The strategy is to look for the reaction e+ + e− → γ + A0, where A0 is the dark photon, which cannot be observed directly or via its decay products. The electromagnetic calorimeter plays a key role in the experiment by measuring the energy and position of the final-state γ. The missing four-momentum carried away by the A0 can be evaluated from this information and the particle mass inferred. This paper presents the design, construction, and calibration of the PADME’s electromagnetic calorimeter. The results achieved in terms of equalisation, detection efficiency and energy resolution during the first phase of the experiment demonstrate the effectiveness of the various tools used to improve the calorimeter performance with respect to earlier prototypes
Commissioning of the PADME experiment with a positron beam
The PADME experiment is designed to search for a hypothetical dark photon A' produced in positron-electron annihilation using a bunched positron beam at the Beam Test Facility of the INFN Laboratori Nazionali di Frascati. The expected sensitivity to the A'-photon mixing parameter ϵ is 10-3, for A' mass ≤ 23.5 MeV/c 2 after collecting ∼1013 positrons-on-target. This paper presents the PADME detector status after commissioning in July 2019. In addition, the software algorithms employed to reconstruct physics objects, such as photons and charged particles, and the calibration procedures adopted are illustrated in detail. The results show that the experimental apparatus reaches the design performance, and is able to identify and measure standard electromagnetic processes, such as positron bremsstrahlung and electron-positron annihilation into two photons
Externalities and the nucleolus
In most economic applications, externalities prevail: the worth of a coalition depends on how the other players are organized. We show that there is a unique natural way of extending the nucleolus from (coalitional) games without externalities to games with externalities. This is in contrast to the Shapley value and the core for which many different extensions have been proposed
The beam and detector of the NA62 experiment at CERN
NA62 is a fixed-target experiment at the CERN SPS dedicated to measurements of rare kaon decays. Such measurements, like the branching fraction of the K+ → π+ ν bar nu decay, have the potential to bring significant insights into new physics processes when comparison is made with precise theoretical predictions. For this purpose, innovative techniques have been developed, in particular, in the domain of low-mass tracking devices. Detector construction spanned several years from 2009 to 2014. The collaboration started detector commissioning in 2014 and will collect data until the end of 2018. The beam line and detector components are described together with their early performance obtained from 2014 and 2015 data
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