ne Appearance Experiment with NuMI Beam

1
ne Appearance Experiment with NuMI Beam

• Physics Motivation
• Physics potential of the Off-axis NuMI Beam
• Backgrounds and Detector Issues
• Off-axis Experiments evolution of the
  accelerator and detectors
• Scenarios

PAC, November 15, 2002 Adam Para
2
Neutrino Experiments vs Standard Model

• Part I - 1970s-1980s Crucial evidence
• Discovery of neutral currents
• Measurements of sin2qW
• Scaling violation and first quantitative evidence
  for QCD
• Part II late 1990s first evidence for physics
  beyond the standard model
• Neutrino mass and oscillations
• Part III 200x future studies of physics
  beyond the standard model
• Just an extension (additional 9? 7? Parameters) ?
• first glimpse at physics at the unification
  scale ?
• Extra dimensions?
• Unexpected?

3
Neutrino beams and experiments a historical
perspective

• Neutrino beams represent a major investment of
  the laboratories.
• They tend to be built as a flexible facility,
  rather that than a single purpose beam.
• Fermilab dichromatic beam, SSQT, NuTeV
• CERN, WANF narrow band beam (160-300 GeV),
  sevaral versions of WBB
• Fermilab, NuMI horn focused, variable energy,
  on- and off-axis
• They offer an opportunity for multiple
  experiments, concurrently or in sequence
• Fermilab HPWF, CITF, CnFRm, Lab E, 15 ft BC,
  NuTeV, oscillation expt
• CERN, WANF CDHS, CHARM, BEBC, GGM, CHARM II,
  Chorus, Nomad

4
The outstanding questions, AD2002

• Neutrino mass pattern This ?
  Or that?

• Electron component of n3 (sin22q13)

• Complex phase of s ?? CP violation in a neutrino
  sector ?? (?) baryon number of the universe

• mixing angle q23 sin22q23 1 e. New
  symmetry? Broken?

5
The key nm ? ne oscillation experiment

A. Cervera et al., Nuclear Physics B 579 (2000)
17 55, expansion to second order in
6
Observations

• First 2 terms are independent of the CP violating
  parameter d
• The last term changes sign between n and n
• If q13 is very small ( 1o) the second term
  (subdominant oscillation) competes with 1st
• For small q13, the CP terms are proportional to
  q13 the first (non-CP term) to q132
• The CP violating terms grow with decreasing En
  (for a given L)
• CP violation is observable only if all angles ? 0
• Two observables dependent on several physics
  parameters need measurements at different L and
  E ( see talk by K. Whisnant)

7
Anatomy of Bi-probability ellipses

• Minakata and Nunokawa, hep-ph/0108085

cosd

• Observables are
• P
• P
• Interpretation in terms of sin22q13, d and sign
  of Dm223 depends on the value of these parameters
  and on the conditions of the experiment L and E

• d

sind
sin22q13
8
Mass Textures and q13 Predictions, Examples
Altarelli,Feruglio, hep-ph/0206077
9
An Unbiased Opinion NuMI provides an Ideal
Beam for Oscillation Studies
arXivhep-ph/0111131
10
NuMI Neutrino Beam Off-axis detectors

• Choice of experimental conditions
• Baseline
• Beam energy (control of matter effects as an
  amplifier of physics)

• Figures of merit, take 15 mrad angle and 735 km
• 100 CC nm ev/kton/year ( 4x1020 pot)
• 0.25 CC ne ev/kton/year (_at_ 50 ID efficiency)
• 0.25 NC background event
• 33 CC anti nm ev/kton/year

11
Two phase program

• Phase I ( 50-100 M, running 2007 2014)
• 20 kton (fiducial) detector with e35-40
• 4x1020 protons per year
• 1.5 years neutrino (2400 nm CC, 70-80
  oscillated)
• 5 years antineutrino (2600 nm CC, 70-80
  oscillated)
• Phase II ( 500M, running 2014-2020)
• 100 kton (fiducial) detector with e35-40
• 20x1020 protons per year (new proton source?)
• 1.5 years neutrino (60000 nm CC, 70-80
  oscillated)
• 5 years antineutrino (65000 nm CC, 70-80
  oscillated)

12
Oscillation probability vs physics parameters
Parameter correlation even very precise
determination of Pn leads to a large allowed
range of sin22q23 ? antineutrino beam is more
important than improved statistics
13
Antineutrinos resolve the ambiguity
Antineutrino range
Neutrino range
L712 km, En1.6 GeV, Dm232 2.5x10-3 eV2
14
Antineutrinos are very important

• Antineutrinos are crucial to understanding
• Mass hierarchy
• CP violation
• CPT violation
• High energy beams experience antineutrinos are
  expensive.

Ingredients s(p)3s(p-) (large x)
For the same number of POT
NuMI ME beam energies s(p)1.15s(p-) (charge
conservation!) Neutrino/antineutrino
events/proton 3 Backgrounds very similar to the
neutrino case (smaller NC background)
(no Pauli exclusion 25 at 0.7 GeV)
JHF
NuMI
15
ne Appearance Experiment a Primer
This determines sensitivity of the experiment

• Systematics
• Know your expected flux
• Know the beam contamination
• Know the NC backgroundrejection power (Note
  need to beat it down to the level of ne component
  of the beam only)
• Know the electron ID efficiency

16
Sensitivity neefficiency and NC rejection
Major improvement of sensitivity by improving ID
efficiency up to 50 Factor of 100 rejection
(attainable) power against NC sufficient NC
background not a major source of the error, but a
near detectordesirable to measure it ?? low
energy neutrino physics (Kevin McFarland, Jorge
Morfin)
17
Sensitivity of the off-axis experiment
Sensitivity to nominal Ue32 (I.e. neglecting
CP phase d) at the level 0.001 (phase I) and
0.0002 (phase II)

• Error on NC background statistically limited up
  to relatively large exposures
• Systematic error on the NC subtraction does not
  degrade the sensitivity, for good electron ID e
  (gt40)

18
Expected precision of Phase I and II (statistical)
Precision of the determination of the oscillation
probability (rather than sin22q13) is a proper
measure of the performance of the experiment

• Phase II
• Measure 0.01 probability to 5 (n)
• Measure 0.002 probability to 20 (n)

• Phase I
• Measure 0.01 probability to 25 (n)

19
NuMI Of-axis Sensitivity for Phases I and II
We take the Phase II to have 25 times higher POT
x Detector mass Neutrino energy and detector
distance remain the same
20
Result-driven program L, E flexibility
Phase I run at 712 km, oscillation
maximum Where to locate Phase II detector?

• Matter effects amplify the effect increase
  statistics at this location
• Osc. Maximum induces d0/dp ambiguity ? move to
  lower/higher energy
• Matter induces dp/2 vs d3p/2 ambiguity ? move
  to the second maximum

21
JHF as Phase I?

• Goal of the experiment is to establish the
  existence of nm to ne oscillations ? Only
  neutrino running is proposed
• Even with potential antineutrino running there
  will be not enough information to select the
  optimum location of the NuMI Phase II (CP/mass
  hierarchy ambiguity)

Optimal strategy Combine JHF and NuMI Phase I to
select the location of the Phase II detector
22
Determination of mass hierarchy complementarity
of JHF and NuMI
Combination of different baselines NuMI JHF
extends the range of mixing angles
V. Barger, D. Marfatia, K. Whisnant hep-ph/0210428
23
Need to know Dm2 ?

• Variation of the oscillation probability with (so
  far unknown) CP violation phase and mass
  hierarchy much bigger than the one with Dm223
• Sensitivity of the experiment may depend on the
  actual value of Dm223 , but not much room for
  improvement by choosing baseline/energy

24
Optimization of beam energy/detector location ?
Range of variation of the observable effects is
dominated by unknown (so far) physics
parameters Beam energy choice is a tool to sort
out potential ambiguities in the physics
parameters space
25
NuMI Off-axis Detector

• Different detector possibilities are currently
  being studied (Debbie Harris talk)
• The goal is an eventual 20 kt fiducial volume
  detector
• The possibilities are
• Low Z imaging calorimeter with RPCs, drift tubes
  or scintillator
• Liquid Argon (a large version of ICARUS)
• Water Cherenkov counter
• Neutrino detectors is not a rocket science.
  Scaleable, can be built to cost.
• Phase I vs Phase II
• The same/different technology?
• The same/different location?

Too early to tell
26
Beam-Detector Interactions

• Optimizing beam can improve signal
• Optimizing beam can reduce NC backgrounds
• Optimizing beam can reduce intrinsic ne
  background
• Easier experimental challenge, simpler detectors
• of events proton intensity x detector mass
• Split the money to maximize the product, rather
  than individual components (? Doug Michaels talk)

27
Proton economics, long term view

• Cartoon
• Donkey is pulling a cart.
• Cart is overloaded with goodies.
• Overload tips the cart over.
• Donkey is lifted off the ground.
• Despite the great effort donkey is not moving.
• Solution need a bigger donkey.

Booster complex is the oldest element of our
accelerator chain. It is becoming a
bottleneck. Our scientific program will greatly
benefit from a major improvement of the proton
source.
28
What if?

• Solar neutrinos NOT in LMA (Dm212ltlt10-5 eV2)
• CP not measurable in terrestial experiments
• Measure sin22q13 (no ambiquities!)
• Determine mass hierarchy
• sin22q13ltltlt1
• Mesure Dm212 if Dm212 gt 10-4 eV2
• There are no nm -gt ne oscillations
• Set a limit at the level P 10-4
• Determine sin22q23 to better than 1 (systematics
  limited, off-axis beam being a major factor in
  reducing the systematic error)
• MiniBOONE confirms LSND
• Physics even more interesting than in the
  minimal model
• Priorities change
• Cheap electron neutrino detector a great asset
• A bare minimum program determine sin22q23 to 1

29
Project Evolution I (so far)

• May 2002 Workshop ot Fermilab, 140 people
• June 2002 LOI submitted
• September 2002 All about NuMI UCL London, 27
  participants
• Now Argonne- Athens - Berkeley - Boston -
  Caltech - Chicago - College de France - Fermilab
  -Harvard - ITEP - Lebedev - UC-London - LSU - MIT
  - MSU Minnesota-Crookstone - Minnesota-Duluth
  -Minnesota-Minneapolis - TUM-Munchen - NIU -
  Ohio-Athens - Oxford - Pittsburgh - Princeton -
  Rochester - Rutherford - Sao Paulo - Stanford -
  Stony Brook - Sussex- Texas-Austin - TMU-Tokyo -
  Tufts - UCLA - Virginia Tech - York-Toronto(115
  physicists) (red joined since PAC submission)
• Expression of interest from several more
  institutions

30
Project Evolution II (possible)

• November January technology focused workshops
• Gas based detector MSU
• Liquid argon UCLA
• January 24-26, SLAC Off-axis detector for
  NuMI workshop (narrow down the technology range,
  focus activities on proposal preparation)
• Spring 2003 workshop on the beam intensity/proton
  upgrades
• Spring 2003 answers to the PAC questions
• Summer 2003 Proposal for the RD and near
  detector construction
• 2004 site selection for the far detector
• Summer 2004 Proposal for the Phase I detector
  and RD fpr the Phase II
• 2005 near detector operational, start
  construction of the far detector
• 2007 start data taking with the far detector

31
Wish list for help from the PAC

• Endorse long term neutrino program for Fermilab
• help with attracting foreign and domestic
  collaborators
• Credibility vis-à-vis potential funding agencies
  (University-based program at DOE, NSF/MRE,
  foreign contributions)
• Encourage lab management to submit a request for
  the construction funds in FY2005
• Encourage lab management to develop a scenario to
  attain or to exceed the design NuMI beam
  intensity
• Encourage lab management to develop a long term
  (15-20 years) plan for the increase of the proton
  
• Help with the choice of the scope of the Phase I
  of the program
• 20? 30? 50? Kton
• 50? 100? M
• (there appears to be no rational arguments in the
  absence of the theoretical predictions.
  Scientific/political/sociological judgment is
  needed)

32
Conclusions

• Neutrino Physics is an exciting field for many
  years to come
• Most likely several experiments with different
  running conditions will be required to unravel
  the underlying physics
• Off-axis detectors offer a promising avenue to
  pursue this physics
• Fermilab/NuMI beam is uniquely matched to this
  physics in terms of beam intensity, flexibility,
  beam energy, and potential source-to-detector
  distances that could be available
• Exciting element of the scientific program of the
  laboratory for the next 20 years

33
Detector(s) Challenge

• Surface (or light overburden)
• High rate of cosmic ms
• Cosmic-induced neutrons
• But
• Duty cycle 0.5x10-5
• Known direction
• Observed energy gt 1 GeV

• Principal focus electron neutrinos
  identification
• Good sampling (in terms of radiation/Moliere
  length)
• Large mass
• maximize mass/radiation length
• cheap

34
Important Reminder

• Oscillation Probability (or sin22qme) is not
  unambigously related to fundamental parameters,
  q13 or Ue32
• At low values of sin22q13 (0.01), the
  uncertainty could be as much as a factor of 4 due
  to matter and CP effects
• Measurement precision of fundamental parameters
  can be optimized by a judicious choice of running
  time between n and n

35
Optimum Run Strategy

• Start the experiment with neutrinos
• Run in that mode until either
• A definite signal is seen, or
• Potential sensitivity with antineutrinos could be
  significantly higher (x 2?) than with neutrinos
• Switch to antineutrinos and run in that mode
  until either
• A definite signal is seen
• Potential sensitivity improvement from additional
  running would be better with neutrinos

36
Backgrounds Summary

• ne component of the beam
• Constrained by nm interactions observed in the
  near MINOS detector (p)
• Constrained by nm interactions observed in the
  near MINOS detector (m)
• Constrained by pion production data (MIPP)
• NC events passing the final analysis cuts (p0?)
• Constrained by neutrino data from K2K near
  detector
• Constrained by the measurement of EM objects as
  a function of Ehad in the dedicated near detector
  
• Cosmics
• Cosmic muon induced stuff overlapped with the
  beam-induced neutrino event
• (undetected) cosmic muon induced which mimics the
  2 GeV electron neutrino interaction in the
  direction from Fermilab within 10 msec beam gate

• Expected to be very small
• Measured in a dedicated setup (under
  construction)

37
NuMI Beam wide range of possible sites

• Collection of possible sites, baselines, beam
  energies
• Physcis/results driven experiment optimization
• Complementarity with other measurements (Cluster
  of detectors? JHF? gt K. Whisnants talk)

38
Receipe for an ne Appearance Experiment

• Large neutrino flux in a signal region
• Small background
• Efficient detector with good rejection against NC
  background
• Large detector

• Lucky coincidences
• distance to Soudan 735 km, Dm20.025-0.035 eV2
• 
  gt large cross
  section
• Below the tau threshold! (BR(t-gte)17)

39
Beam Systematics Predict the Far Spectrum
Event spectra at far detectors located at
different positions derived from the single
near detector spectrum using different particle
production models. Four different histograms
superimposed
Total flux predictable to 1-2 .
40
Off-axis magic ( D.Beavis at al. BNL, E-889)
1-3 GeV intense beams with well defined energy in
a cone around the nominal beam direction
41
Sources of the ne background
ne/nm 0.5
All
K decays

• At low energies the dominant background is from
  m?enenm decay, hence
• K production spectrum is not a major source of
  systematics
• ne background directly related to the nm spectrum
  at the near detector

42
NuMI Beam Layout
Near off-axis detector
43
Fighting NC backgroundthe Energy Resolution
Cut around the expected signal region to improve
signal/background ratio
44
Determination of mass hierarchy
Matter effects can amplify the effect,
sgn(Dm2131), d3p/2, or reduce the effect
sgn(Dm213-1), dp/2, and induce the
degeneracy at smaller values of sin22q13. In the
latter case a measurement at the location where
matter effects are small (even with neutrinos
only!) breaks the degeneracy and extends the
hierarchy determination to lower values of
sin22q13. ?? complementarity of NuMI and JHF
45
Background rejection beam detector issue
n spectrum
NC (visible energy), no rejection
Spectrum mismatch These neutrinos contribute to
background, but no signal

• ne background

ne (Ue32 0.01)
NuMI low energy beam
NuMI off-axis beam
These neutrinos contribute to background, but not
to the signal
46
Two body decay kinematics
At this angle, 15 mrad, energy of produced
neutrinos is 1.5-2 GeV for all pion energies ?
very intense, narrow band beam

• On axis En0.43Ep

47
Two Most Attractive Sites

• Closer site, in Minnesota
• About 711 km from Fermilab
• Close to Soudan Laboratory
• Unused former mine
• Utilities available
• Flexible regarding exact location
• CNA study
• Further site, in Canada, along Trans-Canada
  highway
• About 985 km from Fermilab
• There are two possibilities
• About 3 km to the west, south of Stewart Lodge
• About 2 km to the east, at the gravel pit site,
  near compressor station

48
Conclusions

• nm -gt ne oscillations provide a powerful tool to
  determine fundamental parameters of the neutrino
  sector
• NuMI neutrino beam offers an unique laboratory
  for an optimal nm -gt ne oscillation experiment
• Matter effects
• L/E optimization
• Off-axis detector(s) in combination with a
  realistic upgrades of the Fermilab proton
  intensity will improve our sensitivity by two
  orders of magnitude over the CHOOZ limit
• Determination of the mass hierarchy and a
  discovery of the CP violation in the neutrino
  sector may be well within our reach
• Neutrino beam will start in 2004. Large
  affordable detector(s) can be constructed in 4-5
  years. Lets do it!

49
Important Reminder

• Experiment measures oscillation probability. It
  is not unambigously related to fundamental
  parameters, q13 or Ue32
• At low values of sin22q13 (0.01), the
  uncertainty could be as much as a factor of 4 due
  to matter and CP effects
• Measurement precision of fundamental parameters
  can be optimized by a judicious choice of running
  time between n and n

50
Neutrino Propagation in Matter

• Matter effects reduce mass of ne and increase
  mass of ne
• Matter effects increase Dm223 for normal
  hierarchy and reduce Dm223 for inverted hierarchy

51
Modular, transportable detector
Sin22q130.05
Super-superbeam somewhere? Here we come!
52
A Quest for NuMI Proton Intensity
NuMI Intensity Working Group, D. Michael/P. Martin
Nominal NuMI year