Apparatus for a Search for T-violating Muon Polarization in Stopped-Kaon Decays

The detector built at KEK to search for T-violating transverse muon polarization in K+ --> pi0 mu+ nu (Kmu3) decay of stopped kaons is described. Sensitivity to the transverse polarization component is obtained from reconstruction of the decay plane by tracking the mu+ through a toroidal spectrometer and detecting the pi0 in a segmented CsI(Tl) photon calorimeter. The muon polarization was obtained from the decay positron asymmetry of muons stopped in a polarimeter. The detector included features which minimized systematic errors while maintaining high acceptance.Comment: 56 pages, 30 figures, submitted to NI

Hybrid Meson Structure at COMPASS

We describe a pion physics program attainable with the CERN COMPASS spectrometer, involving tracking detectors and an electromagnetic calorimeter. COMPASS can realize state-of-the-art pion beam hybrid meson and meson radiative transition studies. We review here the physics motivation for this program. We describe the beam, detector, trigger requirements, and hardware/software requirements for this program. The triggers for all this hybrid meson physics can be implemented for simultaneous data taking. We will investigate hybrid meson production via pion-photon Primakoff and pion-Pomeron diffractive interactions. We will determine new properties of quark-antiquark-gluon hybrid mesons, using unique production methods, to improve our understanding of these exotic mesons. The CERN COMPASS experiment uses 100-280 GeV beams (muon, pion), and magnetic spectrometers and calorimeters, to measure the complete kinematics of pion-photon and pion-Pomeron reactions. The COMPASS experiment is currently under construction, and scheduled to begin data runs in 2001. We carry out simulation studies to optimize the beam, detector, trigger, and hardware/software for achieving high statistics data with low systematic uncertainties in the hybrid meson component of this program. We will improve previous Primakoff Hybrid studies by three orders of magnitude. We implement special detectors and triggers for hybrid meson production reactions. We propose to prepare for these COMPASS pion beam hybrid studies by setting up with muon beam tests.Comment: 12 pages, 2 figures, Contributions to the International Workshop on Hadron Physics with High Energy Muon and Hadron Beams at Fixed Target Experiments, Workshop Chairmen S. Paul and F. Bradamante, Technical University Munich, Oct. 199

Research Proposal for an Experiment to Search for the Decay {\mu} -> eee

We propose an experiment (Mu3e) to search for the lepton flavour violating decay mu+ -> e+e-e+. We aim for an ultimate sensitivity of one in 10^16 mu-decays, four orders of magnitude better than previous searches. This sensitivity is made possible by exploiting modern silicon pixel detectors providing high spatial resolution and hodoscopes using scintillating fibres and tiles providing precise timing information at high particle rates.Comment: Research proposal submitted to the Paul Scherrer Institute Research Committee for Particle Physics at the Ring Cyclotron, 104 page

Inclusive pi^0, eta, and direct photon production at high transverse momentum in p+p and d+Au collisions at sqrt(s_NN) = 200 GeV

We report a measurement of high-p_T inclusive pi^0, eta, and direct photon production in p+p and d+Au collisions at sqrt(s_NN) = 200 GeV at midrapidity (0 gamma gamma were detected in the Barrel Electromagnetic Calorimeter of the STAR experiment at the Relativistic Heavy Ion Collider. The eta -> gamma gamma decay was also observed and constituted the first eta measurement by STAR. The first direct photon cross section measurement by STAR is also presented, the signal was extracted statistically by subtracting the pi^0, eta, and omega(782) decay background from the inclusive photon distribution observed in the calorimeter. The analysis is described in detail, and the results are found to be in good agreement with earlier measurements and with next-to-leading order perturbative QCD calculations.Comment: 28 pages, 30 figures, 6 tables, the updated version that was accepted by Phys. Rev.

Performance study of Kalman Filter track reconstruction algorithms in the FOOT experiment

Il progresso tecnologico ha portato all'evoluzione delle tecniche di radiazione oncologica, tra cui spicca il trattamento di adroterapia, che utilizza particelle cariche come protoni e ioni C. Il vantaggio rispetto alla radioterapia convenzionale, è la peculiare curva di rilascio di dose di particelle cariche nei tessuti, che presenta un massimo localizzato (picco di Bragg) alla fine del cammino. L'obiettivo di un trattamento adroterapico è la localizzazione della massima dose nel volume tumorale con minimo rilascio di dose nei tessuti sani circostanti. Oggigiorno, il Treatment Planning System (TPS) non considera appieno gli eventi di frammentazione, sia del bersaglio di materia organica nel caso di fasci di protoni, sia del proiettile in caso di ioni pesanti. Questo può portare alla sottostima della dose rilasciata negli organi a rischio, compromettendo l'efficacia del trattamento. Il nuovo esperimento FOOT (FragmentatiOn Of Target) si incarica di ricavare dati sperimentali sulla sezione d'urto dei frammenti prodotti nell'interazione tra particelle cariche (protoni e ioni pesanti come C, He e O) e tessuti biologici alle energie di 200-400 MeV/u. Questi dati saranno essenziali sia per il miglioramento dei trattamenti di adroterapia, sia per lo studio e l'ottimizzazione di meccanismi di radioprotezione per gli astronauti in orbita. L'apparato di FOOT consiste in un sistema di tracking in campo magnetico ad alta precisione ed utilizzando l'approccio di cinematica inversa, permette il calcolo della sezione d'urto differenziale di frammentazione nucleare con un'incertezza minore del 5%. La ricostruzione delle tracce si basa sul software SHOE (Software for Hadrontherapy Optimization Experiment), che utilizza il toolkit GENFIT ed il suo algoritmo Kalman di ricostruzione. Questa tesi si occupa dello studio di metodi per l'ottimizzazione della ricostruzione delle tracce, focalizzandosi in particolare sul filtro di Kalman e la sua performance nell'esperimento FOOT