Beam Kaons at MiniBoone

1
Beam Kaons at MiniBoone

• Why are K important?
• MiniBooNE beamline
• Neutrino Flux
• High Energy n
• Little Muon Counter (LMC)
• Future plans

• Robert Nelson
• University of Colorado
• Boulder
• October 24th, 2005

2
K are money

• Intrinsic ne from K are on the same order as our
  expected signal.
• The focus of this talk will be on understanding
  our K background.
• We would like to know this background to lt10
  uncertainty.

Assuming 1021 p.o.t. Dm2 0.4-1.0 eV2
3
MiniBooNE Beamline
Primary beam 8 GeV protons
Secondary beam
Neutrino beam
LMC enclosure

• 70 cm/1.7 l Be target.
• 80 bunches in a 1.6 ms beam spill (5E12 ppp).
• 140 ms pulsed (2-5 Hz) 170 kA horn.
• Focus (-) mesons for n(n-bar).
• 50/25 m decay region.
• 450 m dirt before the detector.

Target and Horn
Bartoszek Engineering
4
Intrinsic ne Neutrino flux

• The expected flux of ne from K is on order of the
  possible oscillation signal.
• This flux needs to be well understood.
• From dead reckoning and internal constraints.

preliminary
5
Dead Reckoning our s(pBe?KX)

• We use many sources of external data to cover our
  parameter space in a Sanford-Wang fit.
• No single data set covers our entire range, or
  theyre at different C.O.M. energies.
• Some inconsistencies lead to a less then ideal
  fit.
• While this data is useful we want HARP data on a
  replica MiniBooNE target at our beam energy (see
  the HARP talk later).
• We also perform internal measurements to
  constrain the S-W fit.

6
Why use an off axis beam monitor?

• The nm flux are mostly from p.
• High energy n in the tank can only come from K
  decays.
• However, we would like to probe the entire
  kinematic region.
• Daughter m from K decays are kinematically
  different then those from p.
• Fixed angle off-axis leads to a separation in
  energy.
• We would like to study low energy n from K as
  well.
• The LMC can probe this space.

preliminary
7
The Little Muon Counter

• Located 70 off-axis of the secondary meson beam.
  Chosen to optimize coverage of phase space.
• Optimized between 0.2-3 GeV/c, measures sign.
• System consists of
• Steel/W collimator (ensures clean signal).
• Veto (removes particles that scatter through the
  collimator).
• Fiber tracking hodoscope (measures a charged
  particles momentum).
• Acceptance counters (fixes tracks to active
  region of tracker).
• W/Scintillator range stack (used for PID) .

8
The Little Muon Counter at Home
9
What should things look like?

• Ideally there should be a good separation between
  m from p and m from K.
• Detector resolution and multiple scattering not
  included.
• Fluctuations from MC statistics.
• Possible background from m scattering in the
  dirt, the collimator reduces them.

Monte Carlo
Energy of m (GeV)
10
Track Reconstruction MC/Data
Range Stack (not to scale)
m acc. (not to scale)
Bend planes
cm
MC
Data
500 MeV muon
p candidate
Position in fiber space (x0.5mm)
beam
11
Internal Constraints on s

• The LMC (blue) covers a significant chunk of the
  phase space (black).
• High energy tank n (red) come only from K and
  depend on n s.
• These measurements complement and overlap each
  other.

12
Path to a result

• We are current accumulating LMC data.
• We are working to understand our m backgrounds
  better.
• Finally, we fit the normalizations of the MC
  distributions to extract a K s constraint for use
  in our ne prediction.
• Our goal is a 5-10 s(pBe?KX) uncertainty.

13
(End of talk)Thank You!