116735072
Multiplicity separation with the reciprocal effect counter in the SELEX experiment
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.
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.
125445448
Investigation of elastic hadron electron scattering at 540 GeV/c in order to measure the electromagnetic charge radius of the proton
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).
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.
123102281
Characterisation and mitigation of beam-induced backgrounds observed in the ATLAS detector during the 2011 proton-proton run
This paper presents a summary of beam-induced backgrounds observed in the ATLAS detector and discusses methods to tag and remove background contaminated events in data. Trigger-rate based monitoring of beam-related backgrounds is presented. The correlations of backgrounds with machine conditions, such as residual pressure in the beam-pipe, are discussed. Results from dedicated beam-background simulations are shown, and their qualitative agreement with data is evaluated. Data taken during the passage of unpaired, i.e. non-colliding, proton bunches is used to obtain background-enriched data samples. These are used to identify characteristic features of beam-induced backgrounds, which then are exploited to develop dedicated background tagging tools. These tools, based on observables in the Pixel detector, the muon spectrometer and the calorimeters, are described in detail and their efficiencies are evaluated. Finally an example of an application of these techniques to a monojet analysis is given, which demonstrates the importance of such event cleaning techniques for some new physics searches.
109949830
The Data Handling Processor for the Belle II Pixel Vertex Detector: efficiency optimization
A major upgrade of the current Japanese B-Factory (KEK-B) is planned for 2015. Together with this new machine (SuperKEK-B) also a new detector, Belle-II, will be operated to fully exploit the planned luminosity of 8 × 1035 s−1cm−2 (40 times larger than previously). One of the major changes in the new experiment will be the introduction of a new sub-detector, close to the interaction point, to allow a precise reconstruction of the decay vertices of the B meson systems. This pixel detector, based on the DEPFET technology, will consist of 20 ladder modules arranged in two cylindrical layers around the beam pipe. Each of the modules will be read-out independently by a combination of analog and digital ASICs placed at both ends of each sensor. The digital chip, the Data Handling Processor (DHP), is designed to control the readout chain and to pre-process and to compress the data. The chip structure and the latest results about its performance optimization will be presented.
108949746
First test beam results on DEPFET pixels for the ILC
Abstract By incorporating a field effect transistor into a fully depleted sensor substrate the DEPFET sensor combines radiation detection and amplification in each pixel, resulting in very low noise and high spatial resolution. This makes DEPFET sensors a favorable technology for the vertex detector at the planned International Linear Collider (ILC). A prototype system with fast steering chips, a current-based readout chip and a 64 × 128 pixels DEPFET matrix has been built and was operated successfully in the DESY test beam. First results of the studies on two different DEPFET design options are presented in this paper.
11562016
Evidence for the spin-0 nature of the Higgs boson using ATLAS data
Studies of the spin and parity quantum numbers of the Higgs boson are presented, based on protonproton collision data collected by the ATLAS experiment at the LHC. The Standard Model spin-parity J( ...
118662023
Expected Performance of the ATLAS Experiment - Detector, Trigger and Physics
A detailed study is presented of the expected performance of the ATLAS detector. The reconstruction of tracks, leptons, photons, missing energy and jets is investigated, together with the performance of b-tagging and the trigger. The physics potential for a variety of interesting physics processes, within the Standard Model and beyond, is examined. The study comprises a series of notes based on simulations of the detector and physics processes, with particular emphasis given to the data expected from the first years of operation of the LHC at CERN.