Fermilab experiment E835 has measured the cross section for the reaction p̄p→e+e− at s=11.63, 12.43, 14.40 and 18.22 GeV2. From the analysis of the 66 observed events new high-precision measurements ...of the proton magnetic form factor are obtained.
The DarkSide Program Rossi, B.; Agnes, P.; Alexander, T. ...
EPJ Web of conferences,
01/2016, Letnik:
121
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
DarkSide-50 at Gran Sasso underground laboratory (LNGS), Italy, is a direct dark matter search experiment based on a liquid argon TPC. DS-50 has completed its first dark matter run using atmospheric ...argon as target. The detector performances and the results of the first physics run are presented in this proceeding.
Argon is a powerful scintillator and an excellent medium for detection of ionization. Its high discrimination power against minimum ionization tracks, in favor of selection of nuclear recoils, makes ...it an attractive medium for direct detection of WIMP dark matter. However, cosmogenic 39Ar contamination in atmospheric argon limits the size of liquid argon dark matter detectors due to pile-up. The cosmic ray shielding by the earth means that Argon from deep underground is depleted in 39Ar. In Cortez Colorado a CO2 well has been discovered to contain approximately 500ppm of argon as a contamination in the CO2. In order to produce argon for dark matter detectors we first concentrate the argon locally to 3-5% in an Ar, N2, and He mixture, from the CO2 through chromatographic gas separation. The N2 and He will be removed by continuous cryogenic distillation in the Cryogenic Distillation Column recently built at Fermilab. In this talk we will discuss the entire extraction and purification process; with emphasis on the recent commissioning and initial performance of the cryogenic distillation column purification.
We present new precision measurements of the ψ(2S) total and partial widths from excitation curves obtained in antiproton–proton annihilations by Fermilab experiment E835 at the Antiproton ...Accumulator in the year 2000. A new technique of complementary scans was developed to study narrow resonances with stochastically cooled antiproton beams. The technique relies on precise revolution-frequency and orbit-length measurements, while making the analysis of the excitation curve almost independent of machine lattice parameters. We study the ψ(2S) meson through the processes p¯p→e+e− and p¯p→J/ψ+X→e+e−+X. We measure the width to be Γ=290±25(sta)±4(sys) keV and the combination of partial widths Γe+e−Γp¯p/Γ=579±38(sta)±36(sys) meV, which represent the most precise measurements to date.
A VME-based data acquisition system for beam-loss monitors has been developed and is in use in the Tevatron and Main Injector accelerators at the Fermilab complex. The need for enhanced beam-loss ...protection when the Tevatron is operating in collider-mode was the main driving force for the new design. Prior to the implementation of the present system, the beamloss monitor system was disabled during collider operation and protection of the Tevatron magnets relied on the quench protection system. The new Beam-Loss Monitor system allows appropriate abort logic and thresholds to be set over the full set of collider operating conditions. The system also records a history of beam-loss data prior to a beam-abort event for post-abort analysis. Installation of the Main Injector system occurred in the fall of 2006 and the Tevatron system in the summer of 2007. Both systems were fully operation by the summer of 2008. In this paper we report on the overall system design, provide a description of its normal operation, and show a number of examples of its use in both the Main Injector and Tevatron.
The resonance parameters of the χc0, the 13P0 state of charmonium, have been measured at the Fermilab Antiproton Accumulator in the reaction p̄p→χc0→γJ/ψ→γ(e+e−). A large data sample collected during ...the year 2000 run yields the results: M(χc0)=3415.4±0.4±0.2 MeV/c2, Γ(χc0)=9.8±1.0±0.1 MeV, B(χc0→p̄p)×B(χc0→γJ/ψ)×B(J/ψ→(e+e−))=(1.61±0.11±0.08)×10−7. Taking B(χc0→γJ/ψ) and B(J/ψ→e+e−) from the literature, we obtain B(χc0→p̄p)=(4.1±0.3+1.6−0.9)×10−4 and Γ(χc0→p̄p)=(4.0±0.4+1.6−0.9) keV.
Fermilab experiment 711 has investigated proton-nucleus collisions in which two high-transverse-momentum hadrons are produced forming high-mass ++, +{minus}, and {minus}{minus} charged states, using ...an 800-GeV/{ital c} proton beam on targets of beryllium, aluminum, iron, and tungsten. Our data cover the range in dihadron mass from 6 to 15 GeV/{ital c}{sup 2}. We show here that the dependence of the cross section on atomic weight {ital A} can be parametrized as {ital A}{sup {alpha}} where {alpha}=1.043{plus minus}0.011(stat){plus minus}0.025 (syst), and is independent of the charge state of the dihadron system.
Experiment E835 at Fermilab Garzoglio, G.; Gollwitzer, K.; Hahn, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2004, Letnik:
519, Številka:
3
Journal Article
Recenzirano
We provide a comprehensive description of experiment E835 at Fermilab, a high-precision experimental study of charmonium bound states. The
c
̄
c
states are formed in
p
̄
p
annihilations of cooled ...antiprotons stored in the Fermilab Antiproton Accumulator using a dense internal hydrogen gas-jet target. We describe the experimental strategies adopted for detecting the tiny
c
̄
c
resonant signals in the huge non-resonant hadronic background, and for measuring resonance parameters with high precision.
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