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Forward Proton Detector. Nine independent spectrometers each consisting of two detectors. Scattered antiprotons. Scattered Protons. A UP Spectrometer. P UP Spectrometer. Dipole Magnets. Quadrupole Magnets. Quadrupole Magnets. Separator. Separator. z [m]. Dipole Spectrometer. IP.
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Forward Proton Detector Nine independent spectrometers each consisting of two detectors Scattered antiprotons Scattered Protons AUP Spectrometer PUP Spectrometer Dipole Magnets Quadrupole Magnets Quadrupole Magnets Separator Separator z [m] Dipole Spectrometer IP ADOWN Spectrometer PDOWN Spectrometer 109 nsec 78 nsec 78 nsec 109 nsec 200 nsec Reconstruct particle tracks from detector (scintillating fiber) hits Dipole SpectrometerQuadrupole Spectrometers |t| ~ 0.0 GeV2 |t| > 0.8 GeV2 x > 0.04 x > 0.0 18 Pots integrated into DØ readout and inserted every store from Jan 2004 to Feb 2006 DOE Review Nov. 14, 2008 Arlington
Low Luminosity Proposal Proposal I: Run with injection tune (*=1.6m), 1 p on 4 pbar (originally 2x4 but CDF not interested), no low squeeze, collisions by ramping down separator voltages. This particular configuration is required to minimize setup time and extra collisions. (1x1 actually achieved)
pot position integ. luminosity Elastic t Distribution estimated t range accessible with injection tune
Some pots less than 4 mm from beam, limited by rate or in-limit switch
Error propagation Elastic d/dt Main sources of error: - Uncertainty in pot positions=300 mm - Uncertainty in beam divergence=5mrad - Uncertainty in efficiencies - Uncertainty in Luminosity - Uncertainty in Ansatz function used in MC Luminosity is determined by comparing # jets from run IIA and High b store: Lumi = 30.6 ± 4.0 nb-1 Systematic errors included Statistical Errors only
Elastic d/dt average DØ PRELIMINARY Carlos Avila (Bogota) main analyst Brandt editing physics note/paper
Inclusive Double Pomeron Strategy • Use prescaled single arm triggers to model background • by randomly combining a p and a pbar event; compare to • DPOM trigger which should include the background + correlated • ppbar events. • Backgrounds include (SD, halo, ELAS(1), DPOM(1)) in various • combinations. • We can measure t distributions of SD (one side LM on and one • side off), halo (flag with TDC), ELAS(1) (from Elastic samples), • assume DPOM(1)= DPOM(2), and fit for fraction that are • DPOM-like, which should be higher in DPOM trigger. • Apply cuts (halo rejection, primary vertex), and refit, should get • higher DPOM fraction
Inclusive Double Pomeron After vertex cut, fake background appears to have a higher ELAS(1) component. Vlastaabandonned analysis, Arnab has taken over, working on DØ low pT tracking <t>=0.63 <t>=0.99 DPOM trigger Fake Background Work in progress to validate and quantify
DØ Summary • Thanks to hard work of Carlos we finally now have a preliminary measurement of elastic d/dt in the range 0.2<|t|<1.3 (Gev/c)2. • The delay in the analysis is finding the trigger efficiencies and the hit reco efficiencies which are correlated given the fact that they come from the same source: THE FIBERS. • Publishing this paper will be a great relief and will pave the way for future publications, such as inclusive double pomeron (Arnab) • I’ve taken over the editing of the hardware paper which was stalled, and expecttopublishthison similar timescale in NIM or J Inst. • Arnab isdoing tracking shifts, my only DØ involvementistryingtogetoutpapers