NuMuBar Group Summary

1
NuMuBar Group Summary

• Jeff Hartnell and Donna Naples
• MINOS Collaboration meeting
• Fermilab, September 2007

2
Physics goals (reminder)

• Short term
• Publish direct limits (or exciting discovery)
• nu -gt nubar transitions
• nubar oscillation parameters (dm2bar, sin2thbar)
• using nubar events in current beam (6)
• Lorentz violation
• Longer term
• Direct measurement of nubar oscillation
  parameters
• propose to take 1e20 POT of reversed horn
  current data (focus pi-)

3
Introduction

• Lorentz Violation
• CSS comparisons
• Systematics study
• Reversed ND B-field study
• NuMuBar Matrix Method Extrapolation
• ND Edge effect
• Spatial dependence of bkg
• NuMuBar running

4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
Lorentz Violation Plans

• Consensus from meeting attendees that we should
  move forward and present the collaboration with a
  package for blessing in the next few weeks
• Following blessing approval
• write a PRL paper
• ask Mark to form a paper committee

8
(No Transcript)
9
NuDST ntuples

• All using the same files with the same
  preselection
• fiducial volume, trkfitpass, ntrkgt1, good coil
  current, good beam, etc
• Code is in NtupleUtils and NuMuBar in cvs
• Can be easily reconfigured to use different sets
  of cuts, containment criteria, etc
• e.g. used by Justin to independently check CC
  matrix method analysis
• http//www-pnp.physics.ox.ac.uk/hartnell/code/Ntu
  pleUtils/doc/NuDST.html

10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
Sensitivity of Charge Sign Selection to B-field
Uncertainties(Istvan Danko, Pittsburgh)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
Reversed ND Bfld Study (Alex Himmel)A
cross-check of the magnetic field and the MC
18
Can we reverse the field successfully?

• Compare 2nd and 3rd week of reversed field
• (there was a week of normal running in between)

Neutrinos
Anti-neutrinos
?2/n 5.9/10 P 82
?2/n 6.1/10 P 81
Flat to 5 between 2-12GeV
Flat to 1 below 10GeV
19
Preliminary Event Rates (test of how well MC
reproduces the different acceptance) A difference
would be indicative of a normalisation systematic
error
Events per 0.97e19 PoTs, E lt 30 GeV
20
(No Transcript)
21
NuMuBar Matrix Method Extrapolation(Justin Evans)
22
Much cross-checking, validated against Nikis
version, same to 1
23
ND data/MC discrepancy in track end
position(Alex Himmel)
24
(No Transcript)
25
Understanding the ND Performance(JJH)
26
Spatial Dependence of Bkg in ND

• Discovered that the mis-id CC events have a
  strong spatial dependence (x5)
• Thought to be a B.dL effect (still to prove)
• Systematic effects of selecting events off the
  beam centre need to be evaluated

Background events only
27
Roadmap to first publication

• A lot of good work has been done
• but were not as far along as I had hoped
• However, momentum has recently built, group
  effort has doubled in size
• Donna and Istvan joined
• Alex is done with qualifiers
• Justin needs to have his thesis done by February
• Still REALLY welcome new people
• Two main topics to focus on
• Finishing the charge separation selection
  systematics study
• Develop the fit to incorporate the systematics
• Present MDC results of full analysis chain in
  Texas
• Have results for Neutrino 2008

28
Anti-neutrino Running

• Chance to make first direct observation of
  NuMuBar disappearance
• Important test of standard neutrino model
• hugely significant if not standard
• Gives us a significant additional paper/result to
  show at conferences
• Initial studies show 1e20 POT is enough to
  observe statistically significant disappearance
  K2K like result Pedro and Caius
• Wasted potential if we dont do it
• Sooner is better than later (in my personal
  opinion...)

29
Two Possible Scenarios

• Plan A
• Run 1e20 POT with anti-neutrinos straight after
  2008 shutdown
• maximises chance of getting the data
• have best measurement for longer
• maintain interest in minos
• Effect on other analyses is small
• sqrt(1e20/5e20)10 bigger statistical errors

• Plan B
• Run 1e20 POT with anti-neutrinos straight after
  2010 shutdown
• Potential conflict with other experiments
• Loosing people to other experiments (T2K,
  reactor, minerva...)
• Effect on other analyses is smaller
• sqrt(1e20/10e20)5 bigger statistical errors

30
Big problem...

• No-one is currently working on this
• (The few) people in current nubar group are
  focussed on getting a paper out with the data we
  have ASAP
• If we want to run with anti-neutrinos sooner
  rather than later then we need to put a proposal
  together starting now.
• need to convince the collaboration that
• we can achieve direct observation with 1e20 POTs
• that its the right thing to do
• then... need to convince Fermilab as well
• As Jenny said, someone needs to own this topic
• great opportunity for someone to take the lead on
  this, potentially influence the minos run plan
  and most importantly, do interesting physics
• MC is already available and a lot of overlap with
  the NuMuBar groups systematic studies
• Please let Donna and I know if you are interested
  in taking the lead on this

31
Conclusion

• Charge Separation Selection (CSS) systematics
  study is underway
• Evaluating individual variables rather than
  hybrid selections
• Group effort to understand the variables
  potentially different systematics
• Effect of B-field has been shown
• We have an extrapolation (Matrix Meth.)
• Need to incorporate systematics in to fit
• Interesting new PRL to come on Lorentz Violation
  (Brian and Stu)