What is the optimal strategy for a high statistics k g pnn measurement at fermilab
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What is the Optimal Strategy for a High Statistics K + g pnn Measurement at Fermilab?. R. Tschirhart, August 21 st , 2009. What has been Proposed, Accepted, Un-accepted and Studied at Fermilab.

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What is the Optimal Strategy for a High Statistics K + g pnn Measurement at Fermilab?

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What is the Optimal Strategy for a High Statistics K+gpnn Measurement at Fermilab?

R. Tschirhart,

August 21st , 2009

What has been Proposed, Accepted, Un-accepted and Studied at Fermilab

  • Conceptual designs has been developed for a 100-event decay-in-flight charged kaon experiment driven with 120 GeV beam. Designs based on separated beams (CKM) and un-separated beams (KPlus) have been explored:


    These can be realized with 120 GeV stretcher operation* of the Tevatron with minimal impact on the coincident Long-Baseline Neutrino Experimental program. CERN is pursing an in-flight technique using the SPS.

  • Concepts have been developed for 1000-event stopped K+ and low-energy KL experiments driven by high duty factor 8 GeV proton beam.

    See: http://project-x-kaons.fnal.gov/

    *Syphers, AD-DocDB 2222, 2849

August 21st 2009. R. Tschirhart - Fermilab

Summary of 8 GeV Studies:

  • Winter/Spring 2008:

    Project-X era with 200 kW of 8 GeV beam. Concepts for 1000 event K+ and KL experiments were developed based of stopping K+ techniques and a KOPIO TOF techniques with a pencil beam.

  • Summer 2008:

    Developed a concept for a 40-event/year K+ experiment driven with 30 kW of 8 GeV beam before the Project-X era using the Debuncher/Accumulator complex. Discussed with the Fermilab PAC, which encouraged consideration of experiments beyond the reach of the CERN NA62 experiment.

August 21st 2009. R. Tschirhart - Fermilab

BNL E787/E949: Stopping K+ Experiment that established the K+->pnn decay process

August 21st 2009. R. Tschirhart - Fermilab

CKM Detector

August 21st 2009. R. Tschirhart - Fermilab

KPLUS Detector

August 21st 2009. R. Tschirhart - Fermilab

The Tevatron Stretcher Concept

  • Can be readily realized after Run-II.

  • Good use of a SC machine:

  • 1) Match Tevatron energy to Main Injector energy. No ramping.

  • 2) Clean single pulse transfer from MI to the Tevatron at 120 GeV.

  • 3) Slow spill beam out of the Tevatron with very high duty factor.

  • Impact on NuMI operations is similar (~10%) to the current test-beam and E906 impact.

  • SEB extraction of beam is easier than at 8 GeV. Beam-charge/Beam-power is x15 better. Proposed SEB performance is comparable to 1997 TeV FT.

  • Keeping Tevatron “on ice” about ~$6M/year. Tevatron Stretcher power and cryo is $8M/year + staff, estimated total of about $15M/year.

August 21st 2009. R. Tschirhart - Fermilab

How might the CKM design scale with running time, duty factor and additional acceptance?

  • CKM assumed 4680 hours/year of accelerator operations.

  • CKM assumed 5x1012 protons/3-seconds with a 33% duty factor.

  • CKM sensitivity based on just PNN1 acceptance.

  • CKM 100 event sensitivity is based on a 1x10-10 BR.

    CKM at the Tevatron Stretcher:

    5000 hours/4680 hours = x1.1

    (100x1012 protons/26-seconds)/(5x1012 protons/3-seconds)* = x2.2

    (5 years of running)/(2 years of running) = x2.5

    (PNN2 Acceptance = PNN1 Acceptance) = x2.0

    Correction for SM Branching Ratio = x0.8


    *(Instantaneous rates 80% of CKM design) x9.7

August 21st 2009. R. Tschirhart - Fermilab

Issues with Advancing a CKM Design

  • At the time of CKM’s cancellation the Total Project Cost (TPC) was estimated to be $100M in FY2001 dollars by an independent review (Temple review). This escalates to about $140M then-year (2015) dollars.

  • We know more now at Fermilab about the cost of SCRF and the associated infrastructure (cryo-modules, etc) The cost of the SCRF beamline was probably underestimated in 2001.

  • In all likelyhood the cost of CKM in then-year TPC dollars would exceed $150M. Cost drivers are: SCRF, Buildings, Instrumented long decay volume.

  • Fermilab is now advancing Nova ($270M TPC, 2010 construction start), and is pushing Mu2e hard ($200M TPC, 2013 construction start).

  • Project-X accelerator construction is being ambitiously pursued after this.

  • A $150M TPC project must get in line behind these planned projects.

August 21st 2009. R. Tschirhart - Fermilab

Further Issues with Advancing Another In-flight Experiment.

  • The Fermilab KPlus/P940 proposal design is quite similar to the CERN NA62 design. Advancing a similar experiment does not offer much insurance to the field and arguably is not the best use of resources now that NA62 is rolling.

  • The CKM design arguably has greater sensitivity and better scaling performance with beam power. Nevertheless it will be hard sell to get started as a $150M TPC before the CERN NA62 experiment runs and demonstrates the viability of the in-flight technique.

August 21st 2009. R. Tschirhart - Fermilab

1000-event Sensitivity is not Necessarily a 3% Measurement

  • A 1000 event measurement requires control of systematics and backgrounds at the 1% level. Where are we at here??

  • Backgrounds: e.g., What are the limits of the bifurcation technique employed by E949?

  • Systematics: e.g. Can acceptance and losses be understood to this level?

    We need to address this in any proposal that discusses a 1000-event measurement.

August 21st 2009. R. Tschirhart - Fermilab

Tactical Advantages of Mounting a High Sensitivity Stopped Experiment at Fermilab

  • Technique established, sensitivity scaling is fairly robust.

  • Different technique than NA62.

  • Detector and beamline is relatively small, which means:

  • Existing primary beam-lines and experiment enclosures can be considered.

  • Existing detector solenoids (CDF/D0) can be re-purposed at relatively low cost.

  • Detector volume is small, which controls costs.

  • A then-year TPC of less than $50M is plausible, which is a conceivable schedule match to the Tevatron running as a collider through FY-2011, followed by a 1-year reconfiguration of the complex and then commissioning in 2013.

August 21st 2009. R. Tschirhart - Fermilab


  • Sensitivity, Backgrounds, Systematics.

  • Cost, cost, cost.

  • Who “pays” for operation of the Tevatron?

  • Can a small project jump in line ahead of large projects?

August 21st 2009. R. Tschirhart - Fermilab

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