The foreseen luminosity upgrade for the LHC (a factor of 5-10 more in peak luminosity by 2021) poses serious constraints on the technology for the ATLAS tracker in this High Luminosity era (HL-LHC). In fact, such luminosity increase leads to increase
d occupancy and radiation damage of the tracking detectors. To investigate the suitability of pixel sensors using the proven planar technology for the upgraded tracker, the ATLAS Planar Pixel Sensor R&D Project was established comprising 17 institutes and more than 80 scientists. Main areas of research are the performance of planar pixel sensors at highest fluences, the exploration of possibilities for cost reduction to enable the instrumentation of large areas, the achievement of slim or active edge designs to provide low geometric inefficiencies without the need for shingling of modules and the investigation of the operation of highly irradiated sensors at low thresholds to increase the efficiency. In the following I will present results from the group, concerning mainly irradiated-devices performance, together with studies for new sensors, including detailed simulations.
The B -> D^{(*)} K^- K^{(*)0} decays have been observed for the first time. The branching fractions of the B -> D^{(*)} K^- K^{(*)0} decay modes are measured. Significant signals are found for the B -> D^{(*)} K^- K^{*0} and B^- -> D^0 K^- K^0_S deca
y modes. The invariant mass and polarization distributions for the K^-K^{*0} and K^-K^0_S subsystems have been studied. For the K^-K^{*0} sybsystem these distributions agree well with those expected for two-body B -> D^{(*)} a_1^-(1260) decays, with a_1^-(1260) -> K^- K^{*0}. The analysis was done using 29.4 fb^{-1} of data collected with the Belle detector at the e^+ e^- asymmetric collider KEKB.
A new structure function analysis of CCFR deep inelastic nu-N and nubar-N scattering data is presented for previously unexplored kinematic regions down to Bjorken x=0.0045 and Q^2=0.3 GeV^2. Comparisons to charged lepton scattering data from NMC and
E665 experiments are made and the behavior of the structure function F2_nu is studied in the limit Q^2 -> 0
A new structure function analysis of CCFR deep inelastic nu-N and nubar-N scattering data is presented for previously unexplored kinematic regions down to Bjorken x=0.0045 and Q^2=0.3 GeV^2. Comparisons to charged lepton scattering data from NMC and
E665 experiments are made and the behavior of the structure function F2_nu is studied in the limit Q^2 -> 0.
The lateral and longitudinal profiles of the hadronic showers detected by iron-scintillator tile hadron calorimeter with longitudinal tile configuration have been investigated. The results are based on 100 GeV pion beam data. Due to the beam scan pro
vided many different beam impact locations with cells it is succeeded to obtain detailed picture of transverse shower behavior. The underlying radial energy densities for four depths and for overall calorimeter have been reconstructed. The three-dimensional hadronic shower parametrisation have been suggested.
The hadronic shower longitudinal and lateral leakages and its effect on the pion response and energy resolution of iron-scintillator barrel hadron prototype calorimeter with longitudinal tile configuration with a thickness of 9.4 nuclear interaction
lengths have been investigated. The results are based on 100 GeV pion beam data at incidence angle $Theta = 10^o$ at impact point Z in the range from - 36 to 20 cm which were obtained during test beam period in May 1995 with setup equipped scintillator detector planes placed behind and back of the calorimeter. The fraction of the energy of 100 GeV pions at $Theta = 10^o$ leaking out at the back of this calorimeter amounts to 1.8 % and agrees with the one for a conventional iron-scintillator calorimeter. Unexpected behaviour of the energy resolution as a function of leakage is observed: 6 % lateral leakage lead to 18 % improving of energy resolution in compare with the showers without leakage. The measured values of longitudinal punchthrough probability $(18 pm 1) %$ and $(20 pm 1) %$ for two different hit definitions of leaking events agree with the earlier measurement for our calorimeter and with the one for a conventional iron-scintillator calorimeter with the same nuclear interaction length thickness respectively. Due to more soft cut for hit definition in the leakage detectors the measured value of longitudinal punchthrough probability more corresponds to the calculated iron equivalent length $L_{Fe} = 158 cm$.
The detailed information about electron response, electron energy resolution and e/h ratio as a function of incident energy E, impact point Z and incidence angle $Theta$ of iron-scintillator hadron prototype calorimeter with longitudinal tile configu
ration is presented. These results are based on electron and pion beams data of E = 20, 50, 100, 150, 300 GeV at $Theta = 10^o, 20^o, 30^o$, which were obtained during test beam period in July 1995. The obtained calibration constant is used for muon response converting from pC to GeV. The results are compared with existing experimental data and with some Monte Carlo calculations.
We report on a measurement of the decay $K_Lrightarrowmu^+mu^-gamma$ from Fermilab experiment E799. We observe $207$ candidate signal events with an estimated background of $10.5 pm 4.0$ events and establish $B(K_Lrightarrowmu^+mu^-gamma) = (3.23pm 0
.23(stat) pm 0.19(sys))times 10^{-7}$. This provides the first measurement of the $Kgammagamma^*$ form factor in the muonic Dalitz decay mode of the $K_L$.
