Probe for New Physics

1. ACTIVITIES @ VALENCIA q e+ The 3rd generation as Experimental and technological approach Probe for New Physics q e- q2 b c l nl Vcb Very High Resolution small animal PET Detects the two photons from positron annihilation. Its resolution approaches the physical limit, the range of positrons in the tissue, about 350 mm. Applications Compton Imaging Compton Prostate Probe. The combination of an intrarectal silicon probe, placed close to the prostate, and an external scintillator would improve resolution by a factor 4 and sensitivity by an order of magnitude. In conventional single photon imaging systems mechanical collimators are used to determine the direction of the incoming photons, coupling detector sensitivity and spatial resolution. Replacing the septa by silicon detectors overcomes the sensitivity-resolution tradeoff. This method, known as electronic collimation, can improve detector sensitivity by orders of magnitude, while remaining independent from spatial resolution. Contrary to conventional Anger cameras, spatial resolution improves with increasing gamma-ray energies. Ring Geometry Compton Camera Simulations predict that this arrangement with 16 mm of silicon detectors would improve by more than 300 times the efficiency of conventional gamma cameras with the same resolution. First Results Reconstructed 131I point source on top of a uniform disc. Photons coming from the object to be imaged compton-scatter in the silicon detector and are absorbed in the scintillator. Determining the impact points and the energy deposited in the first detector, it is possible to locate the source and reconstruct the image. Spatial resolution depends mainly on the uncertainty in the scattering angle, which is driven by the uncertainty in the energy measured by the silicon sensors. Therefore, a good energy resolution for these detectors (~1keV) is essential. Experimental data have been taken with a Compton Camera prototype at the University of Michigan. Images have been reconstructed employing the List Mode Likelihood method. These results were obtained with 300 mm thick silicon pad detectors (8x32 pads, 1.4x1.4 mm pitch). New 1mm thick detectors and improved versions of electronics are currently being tested for a new prototype. DELPHI M.J. Costa, A.Oyanguren, P. Tortosa b mass effects at the Z0 peak from 3 and 4 jet events P. Bambade, M.J. Costa, J. Fuster and P. Tortosa b mass effects have been observed at DELPHI at the Z0 energy by measuring the ratio of the norma- lised n-jet rate for b over light quark hadronic Z0 decays: • n = 3 and 4 jets • Jet clustering algorithms: Durham Cambridge 3 jets NLO massive calculations G. Rodrigo et al. Phys. Rev. Lett. 79 (1997) 193 M. Bilenky et al., Phys. Rev. D60 (1999) 114006 4 jets LO calculations A. Ballestrero et al., CERN-2000-09 Parton level R4bl DELPHI Preliminary LO corrected for hadronisation Hadron level LO – mb (MZ) IMPROVED|Vcb|MEASUREMENT FROMSPECTRAL MOMENTS LO – Mb Cambridge Vcb gives the scale of the unitarity triangle M. Battaglia, M. Calvi, P. Gambino, A. Oyanguren, P. Roudeau, L. Salmi, J. Salt, A. Stocchi, N.Uraltsev 3 jets NLO calculations yc First study of R4bl. NLO not yet available!!! Cambridge R4bl DELPHI Preliminary DELPHI Preliminary Hadron level DELPHI has measured |Vcb| by using the information given by Spectral Moments (hep-ph/0210319). The lepton and hadron moments (Mi(El) and Mi(Mx)) in inclusive b semileptonic de- cays give constraints on theoretical parameters which allow to determine Vcb: Herwig Pythia Vcb is one fundamental parameter of the SM. It governs the transitions between b and c quarks and has to be determined ex- perimentally. At the moment, the dominant uncertainties on Vcb are from theoretical origin so new methods and analyses beco- me necessary to improve this measurement. Vcb(now)=0.0419(1±0.016|meas ± 0.015|fit ±0.010|pert) before the use of moments Vcb had ± 0.05|theouncertainty ! yc In the near future, analyses with larger statistics will give a better measurement of Spectral Moments and will improve the Vcb value. Predictions from generators are confronted with data It is the most precise measurement of mb(MZ) Compton Imaging for Medical Applications CIMA G. Llosá , J. Bernabeu, J. Fuster, C. García, C. Lacasta, F.J. Sánchez