38484024
Precision measurements of the lambda(+)(c) and D0 lifetimes.
We report new precision measurements of the lifetimes of the Lambda(+)(c) and D0 from SELEX, the charm hadroproduction experiment at Fermilab. Based upon 1630 Lambda(+)(c) and 10 210 D0 decays we observe lifetimes of tau[Lambda(+)(c)] = 198.1+/-7.0+/-5.6 fs and tau[D0] = 407.9+/-6.0+/-4.3 fs.
118634488
Nuclear dependence of charm production
Using data taken by SELEX during the 1996–1997 fixed target run at Fermilab, we study the production of charmed hadrons on copper and carbon targets with Σ−, p, π−, and π+ beams. Parametrizing the dependence of the inclusive production cross section on the atomic number A as Aα, we determine α for D+, D0, Ds+, D+(2010), Λc+, and their respective anti-particles, as a function of their transverse momentum pt and scaled longitudinal momentum xF. Within our statistics there is no dependence of α on xF for any charm species for the interval 0.1<xF<1.0. The average value of α for charm production by pion beams is αmeson=0.850±0.028. This is somewhat larger than the corresponding average αbaryon=0.755±0.016 for charm production by baryon beams (Σ−, p).
125445448
Investigation of elastic hadron electron scattering at 540 GeV/c in order to measure the electromagnetic charge radius of the proton
16737596
First observation of the doubly charmed baryon Xi(+)(cc).
We observe a signal for the doubly charmed baryon Xi(+)(cc) in the charged decay mode Xi(+)(cc)-->Lambda(+)(c)K-pi(+) in data from SELEX, the charm hadroproduction experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1+/-0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is 3519+/-1 MeV/c(2). The Gaussian mass width of this state is 3 MeV/c(2), consistent with resolution; its lifetime is less than 33 fs at 90% confidence.
56343042
Polarization of Σ+ hyperons produced by 800 GeV/c protons on Cu and Be
We show that {sigma}{sup +} hyperons produced by 800 GeV/c protons on targets of Be and Cu have significant polarizations (15-20%). These polarizations persist at values of p{sub t}{approx_equal}2 GeV/c and a wide range of x{sub F}. The polarizations from the Cu target are consistently less than from Be. The average ratio of the {sigma}{sup +} polarization from Cu to that from Be is 0.68{+-}0.08.
122636205
Status of DEPFET
Abstract In a DEPFET sensor a MOSFET is integrated on a sidewards depleted p-on-n silicon detector, therefore combining the advantages of a fully depleted silicon sensor with in-pixel amplification. Presently, the DEPFET is mainly developed for two different kinds of applications: imaging spectroscopy in X-ray astronomy and the vertex detector for the International Linear Collider (ILC). In X-ray astronomy, the DEPFET sensor is chosen as focal plane detector for the XEUS mission mainly for its low noise and power consumption. In addition, the scalable pixel size makes it suitable for missions like SIMBOL-X, BepiColombo and WIMS. Using the source follower readout mode, a noise of 1.6e − is obtained at room temperature for single pixel devices. Two types of ILC devices, with and without a high energy (HE) implant, were tested in a testbeam. The signal-to-noise ratios were 100 with and 126 without HE implant. The position resolutions for both devices were found to be better than 6 μm.
122624583
MEPHISTO – a 128-channel front end chip with real time data sparsification and multi-hit capability☆
Abstract The MEPHISTO chip uses a novel binary architecture to achieve a high speed readout for multichannel detectors, like silicon strip detectors or MSGCs. The architecture is an alternative to existing designs with raw data pipelines as are commonly used in particle physics applications. The chip receives 128 digital input signals from an analog front end chip at a rate of up to 80 MHz. The hit pattern is sparsified in real time and only the addresses and interaction times of hits are stored temporarily in FIFOs. Multiple hits per event are possible. A trigger selects interesting events for readout. All other hits are automatically discarded. Untriggered readout at high rates is also possible. The occupied chip area depends on the average data rate which can be very small in many applications. Very compact designs with up to ten times less first level storage can therefore be realized.
121065575
A counting silicon microstrip detector for precision compton polarimetry
Abstract A detector for the detection of laser photons backscattered off an incident high-energy electron beam for precision Compton polarimetry in the 3.5 GeV electron stretcher ring ELSA at Bonn University has been developed using individual photon counting. The photon counting detector is based on a silicon microstrip detector system using dedicated ASIC chips. The produced hits by the pair converted Compton photons are accumulated rather than individually read out. A transverse profile displacement can be measured with μm accuracy rendering a polarization measurement of the order of 1% on the time scale of 10– 15 min possible.