e Appearance Experiment with Off-axis Detector in a NuMI Beam

• Physics• Off-axis NuMI Beam• Detector Issues• Off-axis Experiments: evolution of the

accelerator and detectors • Scenarios

February 15, 2003Adam Para

Neutrinos vs Standard Model

Whereas• There is a major effort to complete the Standard Model (Higgs

search)• There is a broad front of experiments looking for possible

deviations from the Standard Model (SUSY searches, B-physics experiments, g-2, EDM, …)

The first evidence for physics beyond the standard model is here:

• Neutrino mass and oscillations

Where does it lead us?• Just an extension (additional 9? 7? Parameters) ?• First glimpse at physics at the unification scale ? (see-saw??)• Extra dimensions?• Unexpected? (CPT violation ???)

The outstanding questions in neutrino physics, AD2003

1

2

3

e

sB B

B B B

B B B

• Neutrino mass pattern: This ? Or that?

• Electron component of 3

(sin2213)

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

• mixing angle 23 : sin2223 = 1 – New symmetry? Broken?

The key: e oscillation experiment

2

2 2131 23

22 2 212

2 23 12

13 13123

13 13124

213sin sin

2

cos sin sin2

cos sin sin2 2 2

sin sin sin2 2 2

cos

sin

sin B LP

B

ALP

A

L B LALP J

A B

L B LALP J

A B

2

13

13 12 13 23

;2

2 ;

;

cos sin 2 sin 2 sin 2

ijij

F e

m

E

A G n

B A

J

1 2 3 4( )eP P P P P

2 2 2 212 13 12 23

2 213 13( , , ,, ,sin 2 , )sin 2sin 2 , ,sgn( )P Lmf Emm

3 unknown, 2 parameters under control, neutrino/antineutrino

Anatomy of Bi-probability ellipses

sin2213

~sin

~cosObservables are:•P •PInterpretation in terms of sin2213, and sign ofm2

23 depends on the value of these parameters and on the conditions of the experiment: L and E

Minakata and Nunokawa, hep-ph/0108085

Rates differ by factor of 4 for the same sin2213

Mass Textures and 13 Predictions, Examples

Texture 13 sin2213perturba

tionsDegenerate neutrinos, spontaneously broken flavor SO(3)

~0.064

Degenerate neutrinos, democratic mass matrix

~0.019

Inverted hierarchy

~0.001

<<0.001

Normal hierarchy

~0.064

~0.26

1 1

2 21 1 1

2 221 1 1 2

2 22

m

1 0 0 1 1 1

0 1 0 1 1 1

0 0 1 1 1 1

m r m

1 1

1

1

m

1 1

1 1

m

1/ 22

2sun

atm

m

m

1/ 22

2sun

atm

m

1/32

2sun

atm

m

2

2sun

atm

m

2

2sun

atm

m

1/ 2

em

m

0

2 0

Altarelli,Feruglio, hep-ph/0206077

Off-axis NuMI Beams: unavoidable byproduct

•Beam energy defined by the detector position (off-axis, Beavis et al) •Narrow energy range (minimize NC-induced background)•Simultaneous operation (with MINOS and/or other detectors)•~ 2 GeV energy :

• Below tau threshold• Relatively high rates per proton, especially for antineutrinos

•Matter effects to amplify to differentiate mass hierarchies•Baselines 700 – 1000 km

Oscillation probability vs physics parameters

Parameter correlation: even very precise determination of P leads to a large allowed range of sin2223 antineutrino beam is more important than improved statistics

e Appearance Counting Experiment: a Primer

# .

( ) ( ) ( ,100%)e

beame e

CC

of cand NCP

dE E E P E

90%

1.28

( ) ( ,100%( ) )e

beamesens

CL CCP

dE E

N

E P E

C

Systematics:•Know your expected flux•Know the beam contamination•Know the NC background*rejection power (Note: need to beat it down below the level of e component of the beam only)•Know the electron ID efficiency

This determines sensitivity of the experiment

Sources of the e background

At low energies the dominant background is from +e+

+e+ decay, hence

K production spectrum is not a major source of systematics

e background directly related to the spectrum at the near detector

AllK decays

e/ ~0.5%

NuMI Off-axis Detector

Low Z imaging calorimeter:– Glass RPC or– Drift tubes or– Liquid or solid scintillator

Electron ID efficiency ~ 40% while keeping NC background below intrinsic e level

Well known and understood detector technologiesPrimarily the engineering challenge of (cheaply) constructing a very massive

detector

How massive??

50 kton detector, 5 years run => • 10% measurement if sin2213 at the CHOOZ limit, or• 3 evidence if sin2213 factor 10 below the CHOOZ limit (normal hierarchy, =0), or

• Factor 20 improvement of the limit

Fuzzy track = electron

Clean track = muon (pion)

Signal and background

Background examples

NC - 0 - 2 tracks CC - with 0 - muon

Beam-Detector Interactions

• Optimizing beam can improve signal• Optimizing beam can reduce NC backgrounds

• Optimizing beam can reduce intrinsic e

background– Easier experimental challenge, simpler

detectors• # of events ~ proton intensity x detector mass

– Allocate the re$ources to maximize the product, rather than individual components

A Quest for NuMI Proton Intensity1998 Letter from "Now" 2005 2005 2008 2010 2010+John Peoples "current plan" possible possible Recycler Proton

Stacking LinacProtons per Booster batch 7.00E+12 4.50E+12 5.00E+12 5.50E+12 6.00E+12 6.50E+12Batches available for MINOS 5 5 5 10 10 10Relative Efficiency per batch 1 1 1 0.7 0.9 0.95Protons per MI Cycle 3.50E+13 2.25E+13 2.50E+13 3.85E+13 5.40E+13 6.18E+13 1.00E+14

MI Cycle Period (seconds) 1.9 2.5 1.9 2.22 1.72 1 1Beam Power (MW) 0.35 0.17 0.25 0.33 0.60 1.17 1.90NuMI Running time per year (seconds) 2.00E+07 1.50E+07 1.80E+07 1.80E+07 2.00E+07 2.00E+07 2.00E+07

Protons per year 3.68E+20 1.35E+20 2.37E+20 3.12E+20 6.28E+20 1.24E+21 2.00E+21

Nominal “NuMI year”NuMI Intensity Working Group,D. Michael/P. Martin

Two phase program

Phase I (~ $100-200 M, running 2007 – 2014)• 50 kton (fiducial) detector with ~35-40%• 4x1020 protons per year

• 1.5 years neutrino (6000 CC, 70-80% ‘oscillated’)

• 5 years antineutrino (6500 CC, 70-80% ‘oscillated’)

Phase II ( running 2014-2020) (D. Harris)• 200 kton (fiducial) detector with ~35-40%• 20x1020 protons per year (new proton source?)• 1.5 years neutrino (120000 CC, 70-80% ‘oscillated’)

• 5 years antineutrino (130000 CC, 70-80% ‘oscillated’)

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

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

Important element of the HEP program in the US for the next 20 years

Project Evolution (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 LOI submission)

• Expression of interest from several more institutions• January 2003 : Detector Workshop at SLAC ~65 people,

narrow technologies to sampling calorimeters• April 2003: Detector Workshop at Argonne, compare

gas/scintillator detector designs

What size collaboration is needed to construct and do physics with the detector? Do the collaborators

have other, overlapping obligations ?The detector is huge but simple. The size of the

technical/engineering staff is the most critical for for the timely design/construction/installation of the experiment.

At present there are some 45 institutions, 140 physicists involved. More groups are expressing their interest.

While most people have, to a varying degree, other obligations at this time, the strength of the collaboration already now is sufficient to ensure a success of the experiment.

We expect a significant influx of interested parties once the project becomes more real.

What is the timeline/schedule for the Off-Axis beam and detector?

NuMI beam: start operation spring 2005 (Reminder: a major investment of US High Energy Physics)

Detector construction: schedule driven by external factors. An optimistic scenario:

Oct 03 – proposal fall 03 - spring 04 initial reviews, cost and design validation summer 04 - approval 04 - 05 construction of a near detector, preparation of

infrastructure for mass production 05 site selection, start site preparation 06 start construction 07 start data taking with adiabatically growing detector 08 complete construction

What is the estimated project cost including the beam and detector? Please give the basis for the cost estimate.

Beam exists. Three-fold intensity upgrades is estimated to cost $45M.Based of on the work of the joint Beams Division/NuMI/MINOS working group.

A committee dedicated to the review, validation and specific recommendation is being formed.

 Detector costs are based on the existing experience of MINOS

and other experiments, like BELLE, using the same technology. An estimated detector cost is in the range of 1-3 M$ per kton.

Large cost savings can be accomplished by optimization of the longitudinal sampling. The current cost estimates assume 1/3 radiation length sampling which provides a very comfortable background rejection. [Need a complete validated design to have a credible cost estimate]

How does the Off-Axis Detector fit into the evolving world picture, especially the JHF-SuperK experiment,

in terms of adding an important new contribution to ourunderstanding of particle physics?

 Determination of the neutrino mixing matrix, mass hierarchy,

possible studies of CP violation will require multiple precise measurements taken under different conditions (distance, energy, matter effects).

In principle, the NuMI beam provides enough flexibility to complete the entire program, given a sufficienty large number of massive detectors located at different positions. This would be a very long, and very expensive program.

Parallel measurements at JHF, with no matter effects, will help to extract the interesting physics parameters in a shorter (still probably very long) time scale.

A possible new reactor experiment measuring/further limiting 13 would be a great help in reducing the correlations between the parameters of interest.

 

Determination of mass hierarchy: complementarity of JHF and NuMI

Combination of different baselines: NuMI + JHF extends the range of hierarchy discrimination to much lower angles mixing angles

Minakata,Nunokawa, Parke

Two body decay kinematics

* * *

* *

( cos )

sin

L

T

p p E

p p

‘On axis’: E=0.43E

At this angle, 15 mrad, energy of produced neutrinos is 1.5-2 GeV for all pion energies very intense, narrow band beam