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TOF-Based K L  0  Experiment

TOF-Based K L  0  Experiment. L. Littenberg BNL. Low energy beam comes in short bursts. Beam very narrow for extra constraint. 40 ns between microbunches.  directions as well as E measured. TOF-based experiment.

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TOF-Based K L  0  Experiment

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  1. TOF-Based KL0 Experiment L. Littenberg BNL

  2. Low energy beam comes in short bursts Beam very narrow for extra constraint 40 ns between microbunches directions as well as E measured TOF-based experiment • Intense source of 8-GeV protons suggests a low energy approach to studying KL0 (à la KOPIO)

  3. KOPIO • KOPIO at BNL AGS designed to get 90 “equivalent events” in 6000 hours, i.e. statistical error on BR is 1/(90)1/2 • At FNAL Booster, K cross-section is lower (8 vs 24 GeV), fewer protons/spill (22.5 vs 100 TP), but duty cycle is much better • Bottom line - can get ~ 95% of the sensitivity/hour • Could get ~80 equivalent events/5500-hr year • In 3 years, could have 6.5% statistics, • with 4% systematics, 8% measurement • At Project-X, could get about 40% more events/year using 3 more beam, but that’s all.

  4. KOPIO at Project-X • KOPIO instantaneous rate-limited • Sensitivity could be increased by improved resolutions • But already not a cheap experiment, large area of detectors, many constraints • Could the potentially huge intensity increases of Project-X qualitatively change the picture?

  5. Why is the beam so wide? Why not get another constraint? TOF-based experiment To symmetrize the beam would cost factor 20 in K flux

  6. KOPIO Challenge #1: Beamline • Complex, costly series of collimators • 3 large sweeping magnets • Plenty of aperture for particles created upstream to reach fiducial region

  7. Challenges of KOPIO

  8. Challenges of KOPIO

  9. Challenges of KOPIO

  10. Smaller Beam • Nearly impossible vacuum vessel disappears • Geometric acceptance increases since horizontal plane accessible • Makes beamline simpler, cheaper, better • Upstream background disappears, so do some types of background in the fiducial volume • Same microbunch event spoilage disappears • Random vetoes much reduced • Extra kinematic constraint increases S/B • Beam veto probably unnecessary • Beam spoiler probably unnecessary • Gives 72% more kaons/proton • Much reduces neutron spreading • Detector can be symmetrized, geometric acceptance increased • Etc.

  11. Sensitivity of Small Beam Exp. • At the Booster: 30 equivalent events per year • At 1st stage Project-X, 300 equivalent events per year • Can get to 900 equivalent events per year using 60% of 2nd stage Project-X • Experiment might even be improved beyond this…

  12. Conclusions • KOPIO clone would work as well at the Booster as at the AGS & yield somewhat higher sensitivity • But  potential gains at Project-X very limited • ~7% BR measurement at best • High intensity of Project-X made in heaven for the TOF-based KL experiment. • Can use small aperture, symmetric beam - makes for simpler, higher acceptance detector • Can exploit post-KOPIO advances in instrumentation • Can get 300 equivalent events/year at 1st stage of Project-X • Possible to use at least 5 times higher intensity & get ~900 equivalent events/year

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