120390470
STAR CLUSTER: a tracking array for gamma-ray astronomy
SummaryA new type of extensive air shower array-telescope is being constructed, close to the GREX scintillator array at Haverah Park. The design of the new instrument is based on identification and measurement of individual shower particles by means of pattern recognition techniques applied to data from LST chambers above and below a thin sheet of high-Z material. Air showers will be detected in the range from 1014 eV to 1018 eV. The directions of the shower primaries will be reconstructed with an accuracy of a few tenths of a degree using triangulation between tracks of detected shower particles: >1 GeV electrons, photons and muons. Particle densities measured at the detector locations will be used to calculate shower sizes and core locations. Information about the height of production of the high-energy secondaries will be obtained for each shower. This information will be taken into account in calculating the primary energies. It will be used together with the observed muon content (ratio of muons to all particles), to draw conclusions about the nature of the primary particles.
118360847
PLASTEX: A Tracking Experiment at the Centre of the GREX Scintillator Array
73520646
PLASTEX: the palermo-leeds air shower tracking experiment
SummaryAn experiment is described in which air shower measurement are carried out by means of a «track detector» placed in a test location near the center of a conventional array telescope currently in use for gamma-ray astronomy. This array, consisting of scintillators (GREX, operated at Haverah Park (U.K.) by the Department of Physics of the University of Leeds), provides, in the usual way, for each shower it selects, its own estimates of shower direction and shower particle density at the test location. Estimates of the muon density at the test location are provided by a large muon detector in operation nearby. The scintillator array triggers this muon detector and it is able to provide flexibly tailored trigger signals for the track detector. This detector named PLASTEX (acronym for Palermo Leeds Air Shower Tracking Experiment), consisting of tracking chambers above and below a thin sheet of lead, designed to provide data on charged particles incident from the air, on the stopping, scattering and multiplication of these particles in the lead sheet and on charged particles created in the lead sheet by shower photons. From these data estimates are derived of the densities and directional properties of the electrons, photons and muons striking the track detector. These results are to be compared with those given by the conventional detectors and with theoretical predictions given by simulations that are being carried out. The objective is to develop and assess optimal procedures for employing clusters of PLASTEX-type detectors as telescopes for the observation of UHE cosmic rays, including cosmic gammarays, over a very wide energy range.RiassuntoIn questo articolo viene descritto un esperimento (PLASTEX) in cui venogo effettuate misure di sciami cosmici per mezzo di un rivelatore posto al centrol di un telescopio convenzionale per gamma-astronomia alle alte energie (GREX, Haverah Park, Leeds, Gran Bretagna). Il telescopio, costituito da unarray di scintillatori, fornisce, per ogni sciame rivelato, le stime della direzione di arrivo e della densità di particelle in corrispondenza alla posizione del rivelatore di PLAXTEX. La stima del contenuto muonico dello sciame in tale posizione è invece data da un rivelatore di muoni posto nelle vicinanze. L'array di scintillatori pilota tale rivelatore di muoni e fornisce gli opportuni segnali ditrigger al rivelatore di PLASTEX. Quest'ultimo consiste in due camere a tracciamento di muoni separate da un sottile strato di piombo, che possono fornire dati sulle particelle cariche incidenti, sull'arresto, la dispersione e la moltiplicazione di tali particelle nello strato di piombo, e sulle particelle cariche create nel piombo dai fotoni appartenenti allo sciame incidente. Da questi dati vengono derivate le stime delle densità e delle proprietà direzionali degli elettroni, dei fotoni e dei muoni che colpiscono il rivelatore che sono poi confrontate con quelle ottenute dagli scintillatori di GREX e con le predizioni teoriche ricavate da simulazioni attualmente in corso. L'obiettivo è di studiare la possibilità dell'impiego di unarray di rivelatori tipo PLASTEX come telescopi per l'osservazione di radiazione cosmica di energia molto alta.РезюмеОписывается эксперимент в котором измерения атмосферных ливней проводятся с помощью «трекового детектора», помещенного в близи центра обычной антенной решетки, используемой для целей гамма-астрономии. Эта антенная решетка, состоящая из сцинтилляторов, обеспечивает для каждого ливбя его селекцию, оценку направления лицня и определение плотности чстиш в ливне. Определение плотности мюонов в месте регистрации обеспечивается большим мюонным детектором. Система сцинтилляторов запускает этот мюонный детектор и обеспечивает триггерные сигналы для трекового детектора. Этот детектор, называемый PLATEX (Палермо-Лидс трековый эксперимент по детектироцанию атмосферных ливней), котортй состоит из трекоцых камер, расположенных выше и ниже тонкого листа свинца, предназначен для сбора данных о заряженных частицах, падающих из атмосферы, о торможении, рассеянии и мультипликации этих частицв листе свинца, и о заряженных частишах, образованных в листе свинца фотонами ливня. Из полученных выводятся плотности и определяются направления электронов, фотонов, мюонов, попадающих в трекоцый детектор. Эти результаты сравниваются с данными, полученными с помощью обычных детекторов, и с теоретическими предсказаниями, полученными с помощью моделироцания. Цель этих исследоцаний—развить и определить оптимальнню прошедуру для использования детекторов типа PLATEX как телескоппв для наблюдения космическиы лучей сцерхцысоких энергий, включая гамма-лучи в широой огласти энергий.
127546936
A low cost 100 KM**2 air shower detector
178365536
Tracking Chamber Data from PLASTEX: Instrumental Performance for Single Particles
173160312
Modifications and Improvements to the GREX Array at Haverah Park
121744643
Characterisation and compensation of magnetic distortions for the pixel Hybrid Photon Detectors of the LHCb RICH
Abstract The LHCb experiment at LHC, optimised for the study of CP violation, has two RICH detectors to provide particle identification in the momentum range ∼ 2 – 100 GeV / c . The stringent requirements on the photon detectors are met by the custom-made pixel Hybrid Photon Detector. The photon detectors need to operate in the fringe field of the LHCb dipole magnet which will produce distortions of the image detected on the pixel chip which is encapsulated inside the HPD. This paper reports on the experimental characterisation of the image distortions caused by an external magnetic flux density. These measurements allow for the development of a parameterisation of the effects and a compensation algorithm, which are also presented.
17738150
Primordial black holes, phase transitions, and the fate of the universe
Phase transitions in the early universe are prime settings for the production of primordial black holes, since they can break the relatively quiescent homogeneity and isotropy of Friedmann-Robertson-Walker (FRW) cosmologies. These epochs of "symmetry breaking," moreover, can affect the subsequent development of spacetime by changing the evolution of some FRW parameters, including the present age and density of the universe. We discuss the relative importance of such effects on constraining mechanisms of black hole formation.
13621763
What are sterile neutrinos good for
Taken at face value, current experimental data indicate the existence of a new particle, the sterile neutrino, which must be a singlet under the Standard Model gauge group. Although they are not detectable through traditional means, such particles have interesting observable consequences for particle astrophysics and cosmology. Here we examine these implications and discuss, in particular, sterile neutrino dark matter and the relationship between matter-enhanced active-sterile neutrino transformation and the synthesis of heavy elements in supernovae.
17884247
Performance of the LHCb RICH detector at the LHC
The LHCb experiment has been taking data at the Large Hadron Collider (LHC) at CERN since the end of 2009. One of its key detector components is the Ring-Imaging Cherenkov (RICH) system. This provides charged particle identification over a wide momentum range, from 2–100 GeV/c. The operation and control, software, and online monitoring of the RICH system are described. The particle identification performance is presented, as measured using data from the LHC. Excellent separation of hadronic particle types (π, K, p) is achieved.
118055934
Summary of the CKM 2010 Working Group on Rare Decays
Rare decays were essential in the discovery of the CKM mechanism of flavour and CP violation and are highly sensitive probes of physics beyond the Standard Model. In this summary the current status and future prospects of experimental measurements and the Standard Model theory predictions of various rare B, D and K decay observables are discussed. The specific new physics sensitivities of each mode are also briefly reviewed.