Conventional%20Neutrino%20Beams%20Day%202

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Conventional Neutrino BeamsDay 2

• Deborah Harris
• NuFact05 Summer Institute
• Anacapri, Italy
• June 12-13, 2005

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Using Pions to make Neutrinos

• Major Components
• Proton Beam
• Pion Production Target
• Focusing System
• Decay Region
• Absorber
• Shielding

Most nms from 2-body decays p?mnm K?mnm Mo
st nes from 3-body decays m?enenm K?p0ene
n energy is only function of np angle and p
energy
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Questions From Yesterday

• What happens to the nm event rate if you change
  the horn current? (0, 100kA, and 200kA shown)

At 735km
At 1km
Visible Energy (GeV)
Visible Energy (GeV)

• Corrolary What happens if you lower the horn
  current by 15kAmps and move the target back 10cm?

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How can you measure the beam performance?
Pions
Neutrinos
protons
Muons

• Primary Proton Beam Measurements
• Remnant Proton Measurements
• Tales from the front line NuMI and the target
  leak
• Muon Measurements
• 7o muon spectrometer (MiniBooNE)
• Range stack Muon Monitor system (MINOS)

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Neutrino Beamline Instrumentation

• Proton Beam
• Number of Protons on Target
• Position and angle
• Spot size of beam on target
• Proton Losses before target
• Target
• Position and angle
• Is it intact?
• Temperature
• Horns
• Position and angle
• Current
• Is it intact?
• Temperature
• Absorber
• Temperature

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Primary Beam Measurements

• Knowing proton position is important want to
  hit the center of the target
• Knowing angle is important if proton beam is at
  angle, the n beam comes out at an angle as well.
  
• Two ways to measure proton position
• Non-interfering (use induction)
• Interfering (secondary emission monitors)

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Proton Position Measurements

• Beam Position Monitors
• Beam pipe with two isolatedplates (A and B)
• When protons go through, charge is induced on
  both plates
• PositionGain(A-B)/(AB)
• Benefits does not interfere with proton beam
• Deficits can be noisy, can have worse
  resolutionat low proton intensity, gives no
  shape information

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Secondary Emission Monitors

• Secondary Emission when charged particles go
  through metal foil, electrons can be kicked off
• By applying a small electric field you can drift
  the electrons away from the foil (also need high
  vacuum for this!).
• Now imagine a row of very thin foils oriented in
  horizontal and vertical direction
• This gives not only a mean position, but also
  gives you the information of the shape
• Benefits shape and mean position
• Deficits putting matter in beam (but can be as
  low as 10-5 lint)

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Tales from the front NUMI, Dec. 4 2005
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What about seeing the Protons at the end of the
decay pipe?

• Proton spot size at end of pipe is large cannot
  just put in a new secondary position monitor
• Proton rates are now very intense can use
  ionization chambers, but they must be very
  resistant to radiation damage, and can be low
  gain
• Question what else makes it down to the end of
  the decay pipe?
• Muons from pion decay
• Undecayed pions
• Secondary shower particles

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Seeing protons at end of pipe
No target in the way
Target in the way
For most beamlines, this hadron monitor is
really a proton monitor it tells you about the
protons and the target, but not about how well
you are making neutrinos
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Lesson Learned be prepared for disasters
Look at what is between targetand baffle by
shooting protons there!

• Leaky Target at NuMI
• the target has pipes around it that carry water
  to cool it
• On March 23, discovered a leak speculate the
  target surrounded by water
• Use Hadron Monitor to verify that water was
  there, and to check that it hasnt reappeared
  since we solved the problem

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Monitors to Study n Beam (MINOS)
m
m
nm
m
m
p
p
m
m
Hadron Monitor sees uninteracted protons after
decay pipe Muon Monitors 3 different depths
means three different muon
momentum spectra
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Getting to Neutrino Spectrum from Muon Spectrum
(MINOS)

• As you get to higher muon energies, you are
  looking at higher pion energieswhich in turn
  mean higher neutrino energies

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Muon Monitors in Different Energy Neutrino Beams

• By looking at the rates in the three different
  muon detectors, can see how the energy
  distributions of the muons changes
• Can study neutrino fluxes by moving the target
  and seeing how you make more high energy
  neutrinos the farther back you move the target
• Can study fluxes by changing the horn current and
  see how you make more low energy neutrinos as you
  increaste the horn current.

Graphs courtesy S. Kopp
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What else you can do with muonsMeasure K/p
ratio in Beam

• nes from muon decay constrained by nm spectrum
  (since they are part of the same channel)
• Kaons have no such constraint
• Remember problem set to get the ne /nm
• Ratio you would also need to know the K/p
  production ratio (and focusing differences)
• Any way this can be measured in the beam? Beam
  too hot to add Cerenkov counters to get
  track/track information

Decay Maximum pt
p?mnm 30MeV
K ? mnm 236MeV
KL? pmnm 216MeV
Think 2-body decay kinematics
Center of Mass
Lab Frame
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Example from MiniBooNE
Backgrounds from muons that scatter in the
dirt/collimator

• By adding collimator and spectrometer at 7o, they
  will measure
• p/K ratio from difference in peaks
• K/KL ratio from m versus m-

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Hadron Production Measurements

• Measuring relative rates in muon monitors are a
  great handle on neutrino production but
• Delta-ray production means the absolute signal on
  the detector as a function of muon flux is very
  hard to predict.so these measurements can only
  provide relative flux information
• Hadron Production Measurements getting to an
  absolute flux prediction

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Measuring Mesons as they leave Target
Particle Production Experiments HARP (at CERN)
took data with K2K, MiniBooNE targets MIPP (at
Fermilab) will take data With MINOS
target Can take data with small samples, But
need to then model also the Particle showering
in the target
MIPP Running now Will take data with NuMI/MINOS
target And also 1-2 targets
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Uncertainties due to Hadron Production

• MINOS example
• 10-30 uncertainties in absolute rate
• 2-10 uncertainties in far/near comparison

Messier, Ely 2004
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But havent people measured particle production
before?
MINOS Beam
What is not the same Target Material Proton
Energy Proton angular distribution Target length
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Measuring p angular distribution in real beamline

• K2K Gas Cerenkov counter measures angular
  distribution of Pions as function of momentum
• Located right
• after horns
• Works for pions
• above 2GeV

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Measuring p angular distribution in real beamline
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Conventional Neutrino Beam Summary

• Major Components
• Proton Beam
• Production Target
• Focusing System
• Decay Region
• Shielding
• Monitoring

Ways to Understand n Flux Hadron
Production Proton Beam measurements Pion
Measurements Muon Measurements at angles vs
momentum at 0o versus shielding