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Considerations of the Project-X Rare-Decay Research Program. R. Tschirhart May 1 st , 2009. Project-X Research Program.

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project x research program
Project-X Research Program
  • A neutrino beam for long baseline neutrino oscillation experiments. A new two or more megawatt proton source with proton energies between 50 and 120 GeV that would produce intense neutrino beams, directed toward a large detector located in a distant underground laboratory.
  • Kaon and muon based precision experiments driven by high intensity proton beams running simultaneously with the neutrino program. These could include a world leading muon-to-electron conversion experiment and world leading rare kaon decay experiments.
  • A path toward a muon source for a possible future neutrino factory and, potentially, a muon-collider at the Energy Frontier. This path requires that the new proton source have significant upgrade potential.

May 1st 2009. R. Tschirhart - Fermilab

our charge
Our Charge…
  • The accelerator complex defined in the ICD can drive the long-baseline neutrino program, but does not readily provide a platform to pursue a research program in rare muon and kaon decays which requires high duty-factor proton beams.
  • As part of the standard DOE review process the Project-X design team is considering Alternate Conceptual Designs (ACDs) that can meet the research goals of the Mission Need statement. Some of these ACDs may be more readily suited to drive the Project-X rare-decay research program. The Project-X Research Program Task Force is charged to evaluate if and how the ICD and the ACDs can meet the research goals and recommend what R&D is necessary to refine the Project-X specifications required to drive the research program. A draft report is expected on May 31st.

May 1st 2009. R. Tschirhart - Fermilab

project x what is it
Project X: What is it?

8 GeV H- Linac with ILC Beam Parameters (9 mA x 1 msec x 5 Hz)

100-200 kW at 8 GeV for Precision Physics

>2.0 MW at 50-120 GeV

for Neutrino Science

Project X Linac:

ILC-like (0.6 – ~1.0 GeV)

ILC-identical (~1 – 8 GeV)

Vehicle for National & International Collaboration

May 1st 2009. R. Tschirhart - Fermilab

driving the future muon program
Driving the Future Muon Program
  • Muons: Large flux of low energy pions required to make low energy muons that are directed to a stopping target.
  • Mu2e requires an RF structure of about 500 kHz with a high duty-factor. The Mu2e experiment has a conceptual design to reconfigure the Debuncher-Accumulator complex running with about 40 kW of proton beam to drive these requirements.
  • This is a challenging machine, and it is not clear that high duty factor can be achieved in parallel with LBNE beam running.
  • There is no a conceptual design yet for much high proton beam power (> 100 kW).

May 1st 2009. R. Tschirhart - Fermilab

advantages of a cw linac driving the muon program
Advantages of a CW Linac driving the muon program…
  • Yield of low energy pions/proton-kW is better? Not clear, needs simulation work and an analysis of low energy pion yield data sets.
  • Beam extinction required in the Mu2e design could be better, more straightforward.
  • Macro duty-factor could be very high.
  • The difficulties of extracting high power beams from a stretcher ring are removed.

May 1st 2009. R. Tschirhart - Fermilab

driving the future kaon program
Driving the Future Kaon Program
  • Kaons: The production of charged and neutral kaon becomes proportional to proton beam power at proton energies above about 6 GeV. Further, producing beams of kaons in practice requires proton drive energies greater than 6 GeV.
  • A detailed conceptual design has been developed for a decay-in-flight charged kaon experiments driven with 120 GeV beam (CKM). This can be realized with 120 GeV stretcher operation* of the Tevatron with minimal impact on the coincident LBNE program.
  • Conceptual designs have been developed for stopped K+ and low-energy KL experiments driven by high duty factor 8 GeV proton beam.

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

  • A new initiative is developing to pursue a stopped K+ experiment driven with 120 GeV beam from the Tevatron Stretcher*.

*Syphers, AD-DocDB 2222, 2849

May 1st 2009. R. Tschirhart - Fermilab

the tevatron stretcher concept
The Tevatron Stretcher Concept
  • This is a good idea.
  • Example configuration: 1 of every 10 MI pulses (1.5 sec cycle, 4x1013 ppp) is transferred to the Tevatron. 15 second stretcher cycle: Establish DC beam in 1-second, slow-spill to a program of 120 GeV experiments for 14 seconds. Stretcher duty-factor of 93%, a 10% hit on the LBNE program to drive a 120 GeV full program.
  • Beam power is about 50 kW. Resonant extraction of beam is an easier problem: Beam-charge/Beam-power is x15 better.
  • Directorate initially did not like the $10M - $20M operations price take of the stretcher.

May 1st 2009. R. Tschirhart - Fermilab

what about driving kaon experiments with low proton energy beam are there any advantages
What about driving kaon experiments with low proton energy beam? Are there any advantages?

May 1st 2009. R. Tschirhart - Fermilab

k l p 0 nn experimental challenge nothing in nothing out
JPARC approach emphasizes high acceptance for the two decay photons while vetoing everything else:

A hermetic “bottle” approach.

The original KOPIO concept measures the kaon momentum and photon direction…Good! But costs detector acceptance and requires a large beam to compensate. Project-X Flux can get back to small kaon beam!

KLp0nnExperimental Challenge: “Nothing-in nothing out”

May 1st 2009. R. Tschirhart - Fermilab

slide11

KOPIO: Micro-bunch the beam, TOF determines KL momentum.

Fully reconstruct the neutral Kaon in

KL p0 n n measuring the Kaon momentum by time-of-flight.

End at the

decay time and decay point

reconstructed from the

two photons.

Start when proton beam hits the target

Timing uncertainty due to microbunch width should not dominate the measurement of the kaon momentum;requires RMS width < 300ps

May 1st 2009. R. Tschirhart - Fermilab

challenge to experimenters
Challenge to Experimenters

_

  • B(KL0) ~ 310-11 ;

need huge flux of kaons -> high rates

  • Weak Kinematic signature (2 particles missing)
  • Backgrounds with 0 up to 1010 times larger
  • Veto inefficiency on extra particles must be 10-4
  • Neutrons dominate the beam
    • make 0 off residual gas – require high vacuum
    • halo must be very small
    • hermeticity requires photon veto in the beam
  • Need convincing measurement of background

May 1st 2009. R. Tschirhart - Fermilab

possible low energy kaon experimental concepts that exploit exclusive final states
Possible low energy kaon experimental concepts that exploit exclusive final states
  • p-p+ gK0L0 : (200mB, explored by A. Konaka (TRIUMF) in the 1990s)

Two-body kinematics tags both the magnitude and direction of theK0L momentum. Timing of the K0L gp0nn decay photons then establishes the K0L decay vertex. This is great!! …but the p- must be a 1 GeV/c beam with a 5% momentum bite...yield killer.

  • p+n gK0L0p+ : (25 mB @ 2.8 GeV/c proton momentum)

The L0 tags the strangeness of the decay. The protons in this event can not be measured in a rare-decay experiment due to the fierce rate of charged particles. The L0 decay establishes the time of the event. Timing of the K0L gp0nn decay photons then establishes the K0L momentum but not the vertex. This is good. Is it good enough??

May 1st 2009. R. Tschirhart - Fermilab

p p cross section
p-p+ Cross Section

May 1st 2009. R. Tschirhart - Fermilab

pp cross section
pp Cross Section

May 1st 2009. R. Tschirhart - Fermilab

pp strangeness production measured at cosy
pp Strangeness Production Measured at COSY

May 1st 2009. R. Tschirhart - Fermilab

slide17

Total cross section is 50,000 mB

Elastic cross section is 25,000 mB.

p+p0 cross section is 4,000 mB.

L0K0p+ cross section is 30 mB.

May 1st 2009. R. Tschirhart - Fermilab

slide18
May 1st 2009. R. Tschirhart - Fermilab
typical cosy experiment
Typical COSY Experiment

May 1st 2009. R. Tschirhart - Fermilab

d p n deuteron fermi momentum is about 50 mev
D = p+n. Deuteron Fermi-momentum is about 50 MeV.

May 1st 2009. R. Tschirhart - Fermilab

rate considerations for a tagged rare decay k l experiment
Rate Considerations for a tagged rare-decay KL Experiment
  • 1000 event measurement K0L gp0nn at the Standard Model Branching Fraction of 3x10-11 with a 1x10-3 detector efficiency requires 3x1016 produced kaon decays.
  • Assuming 2x107 live-seconds/year for five years, this corresponds to 300 MHz of produced kaons required, which corresponds to a rate in the detector of about 100 MHz just from neutral strange particles.
  • For the p+n gK0L0p+ (25 mB) reaction, this corresponds to 100 mA of beam current on a 10-3 lT target (3mm of LD2). This could be even less beam and even thinner targets if the beam is recycled in a ring.

May 1st 2009. R. Tschirhart - Fermilab

simulation studies with mars laqgsm cooper mokhov striganov
Simulation Studies with MARS/LAQGSM Cooper/Mokhov/Striganov
  • Study the kinematics of p+n gK0L0p+for proton beam momenta between 2.65 GeV/c to 3.0 GeV/c ( Linac energies 1.7-2.1 GeV) .
  • Effect of Fermi momentum and missing protons on possible kinematic constraints. Where does the K0Lgo? How is it’s kinematics correlated with the L0?
  • Are other targets better? Li? , Be?, C? LiD2?
  • Beam deuteron vs target deuteron?

May 1st 2009. R. Tschirhart - Fermilab

potential advantages of low energy tagged kaon experiments
Potential Advantages of Low energy tagged Kaon experiments.
  • Exclusive reactions can improve strangeness purity.
  • Lambda decay tags strangeness and momentum of the neutral kaon.
  • All neutral hadron signature might allow detector rates to be dominated by strangeness decays!
  • Low energy improves Time Of Flight performance in the detector.
  • Target power is very low, can consider internal targets.
  • Opportunity for measuring many rare hyperon decays.

May 1st 2009. R. Tschirhart - Fermilab

toy strangeness factory
Toy Strangeness Factory

2 GeV CW proton beam, 1-10 mA

100-1000 turn internal targets, match drive beam current to burn rate on very thin internal targets. No extraction.

Tagged K0L

Experiment

10-4-10-5 target

Tagged S+, K0 Experiment

H2 Gas target (10-7lT)

1000 event KLgpnn experiment

pp gS+K0p+ , S+ decay, K0 decay,

sensitivity of better than 10-12

May 1st 2009. R. Tschirhart - Fermilab

summary of work items
Summary of Work Items
  • Muons: Need to validate & understand the low energy pion yield estimates from 2-3 GeV proton beam energy.
  • Muons: Is the extinction really better with a CW LINAC?
  • Kaons: Study the p+n gK0L0p+ reaction.
  • Kaons: Should estimate the 1 GeV pi- yield (5% momentum bite) from 8 GeV and 120 GeV protons to evaluate the viability of p-p+ gK0L0 .
  • What about the Tevatron Stretcher? What remaining issues should we study? Maximum SEB power? Operating costs?

May 1st 2009. R. Tschirhart - Fermilab

issues to discuss today
Issues to Discuss Today
  • 1) Brief review of experimental requirements.
  • 2) How can the complex be reconfigured into stretcher rings that can provide a high duty factor for experiments? Can the Accumulator and Debuncher be used simultaneously to drive experiments with different RF beam structure requirements?
  • 3) How can extraction work? What are the losses, beam power limitations?
  • 4) The neutral kaon experiment requires an RF train of pings (see attached description of how this was proposed for the AGS). How can the necessary RF structure be established? What are the limits to ping fidelity? Can a sigma of 100 picoseconds be realized?

May 1st 2009. R. Tschirhart - Fermilab

slide27

At 8 GeV a neutral channel is a neutron beam will a small kaon component. The neutral kaon Experiment requires Time-Of-Flight measurement of netural kaons event by event, which means low-energy kaons (300-1200 MeV) -> Large angles!

May 1st 2009. R. Tschirhart - Fermilab

slide28
BNL Charged K+ Beamline: Channel a low energy separated charged beam to a stopping target: Measure kaon decays at Rest!

@BNL: 800 MeV/c, 4% FWHM Dp bite.

@FNAL: Lower momentum, higher eff??

May 1st 2009. R. Tschirhart - Fermilab

bnl e787 e949 stopping k experiment that observed three k pnn events
BNL E787/E949: Stopping K+ Experiment that observed three K+->pnn events.

May 1st 2009. R. Tschirhart - Fermilab

slide30

Physics Motivation:

Microbunch Separation

AGS KOPIO Requirement slides from Phil Pyle, BNL.

Microbunch separation determined by

the length of time required to clear out kaons

from the previous microbunch.

Difference in time-of-flight between high momentum and low momentum kaons is ~30 nsec

=> 40nsec (25MHz)

Signal efficiency drops when neighboring microbunch too close

May 1st 2009. R. Tschirhart - Fermilab

8 gev beam requirements for kaon experiments
8-GeV Beam Requirements for Kaon Experiments
  • High Duty Factor.
  • High Power 8-GeV Target Station. Stage-I 20 kW, Stage-II 200 kW.

Can the same target station drive both the charged and neutral experiments?......Why Not??

  • RF Train:
  • 38 nsec pulse spacing
  • 10-3extinction outside of +/- 2 nsec from ping core.
  • 100 psec ping sigma (goal).

May 1st 2009. R. Tschirhart - Fermilab

slide32

Structure AGS of Beam

Start of Cycle

Start of Spill

End of Spill and Cycle

0 sec

2.3 sec

5.3 sec

AGS Cycle

Spill Structure

Injection and

acceleration

Extraction

mbunch

spacing

40 ns between

microbunches

mbunch

structure

200 ps RMS

Microbunch width

Proton intensity

Time

May 1st 2009. R. Tschirhart - Fermilab

slide33

Test Beam Results: Microbunch Width

Simulation

Data

93 MHz cavity at 22 kV

gaves= 240 ps.

93 MHz cavity at 22 kV

gaves = 217 ps.

Simulation

Data

Microbunch time, in ns

Microbunch time, in ns

May 1st 2009. R. Tschirhart - Fermilab

slide34

AGS Test Beam Results: Interbunch Extinction

Data

Simulation

4.5 MHz cavity at 130 kV

gavee= 8 (+/- 6) x 10-6

4.5 MHz cavity at 130 kV

gavee= 1.7 (+/- 0.9) x 10-3.

Interbunch

events

Simulation

Data

Interbunch

events

Microbunch time, in ns

Microbunch time, in ns

May 1st 2009. R. Tschirhart - Fermilab

slide35
May 1st 2009. R. Tschirhart - Fermilab
slide36

24 GeV/c

8 GeV/c

kinetic energy of mesons > 294 MeV

Sergei Striganov

May 1st 2009. R. Tschirhart - Fermilab