fine-grained near detector(s) at jhf: purpose and thoughts

Fine-Grained Near Fine-Grained Near Detector(s) at JHF: Detector(s) at JHF:

Purpose and ThoughtsPurpose and Thoughts

Kevin McFarlandKevin McFarlandUniversity of RochesterUniversity of Rochester

31 October 200231 October 2002

31 October 200231 October 2002 Kevin McFarlandKevin McFarland 22

Precision P(Precision P(→→ee) and P() and P(→→))• Conventional “superbeams” will be our only Conventional “superbeams” will be our only

windows into windows into →→ee for a long time… for a long time…

– Analogous to |VAnalogous to |Vubub| in quark sector| in quark sector

– Long time before Long time before sources or “ sources or “ beams” beams”• Studying in neutrinos and anti-Studying in neutrinos and anti-

neutrinos gives us neutrinos gives us magnitudemagnitude and and phase phase information on |Uinformation on |Ue3e3||

• Comparing two precise Comparing two precise measurements at different E measurements at different E or L/E does sameor L/E does same

• P(P(→→)) is mixing maximal? is mixing maximal?

Precise Precise m23

Sign of m23

Ue3|


Where do Cross-Sections Where do Cross-Sections matter?matter?

• →→, , mm222323, , 2323

– Signal is suppression in 600-Signal is suppression in 600-800 MeV bin800 MeV bin

• Dominated by non-QE Dominated by non-QE backgroundbackground– 20% uncertainty in non-QE 20% uncertainty in non-QE

is comparable to statistical is comparable to statistical errorerror

• Non-QE background feeds Non-QE background feeds down from Edown from E>E>Epeakpeak

1ring FC -like

Reconstructed E (MeV)

Oscillation with m2=3×10-3

sin22=1.0

No oscillation

Non-QE


Where do Cross-Sections Where do Cross-Sections matter?matter?• →→ee, , 1313

– Shown at right is most Shown at right is most optimistic optimistic 1313; we may instead ; we may instead be fighting against backgroundbe fighting against background

• Equal parts NC Equal parts NC 00 and beam and beam ee background background– NC NC 00 cross-section poorly cross-section poorly

knownknown

– We can calculate We can calculate CCCC((ee)/)/CCCC((). ). Is it right? Is it right?

• We must prove to the world We must prove to the world we are right with S/N of 1:1we are right with S/N of 1:1– Precision measurement is the Precision measurement is the

endgameendgame

sin22e=0.05 (sin22e 0.5sin2213)


Where do Cross-Sections Where do Cross-Sections matter?matter?

• →→ee vs vs →→ee, , – Cross-sections very Cross-sections very

different in two modesdifferent in two modes– ““Wrong sign” background Wrong sign” background

only relevant in anti-only relevant in anti-neutrinoneutrino• Crucial systematic in Crucial systematic in

comparisoncomparison

• Need Need CCCC(()/)/CCCC(() at high ) at high precision in sub- to few-precision in sub- to few-GeV regionGeV region


Status of Cross-SectionsStatus of Cross-Sections• Not well-known at 1-few GeVNot well-known at 1-few GeV

– Backgrounds for JHFBackgrounds for JHF– Signal and Background at NUMI 0.7Signal and Background at NUMI 0.700 off-axis proposal off-axis proposal

n–p0

nn+


Low Energy Neutrino cross-Low Energy Neutrino cross-sections sections

Neutrino interactionsNeutrino interactions

• Quasi-Elastic / Elastic , Quasi-Elastic / Elastic , nn→→--pp (x =1, W=M (x =1, W=Mpp) ) – well measured and described by well measured and described by

form factorsform factors– BUT, need to account for Fermi BUT, need to account for Fermi

Motion/binding effects in Motion/binding effects in nucleus, e.g. Bodek-Ritchie nucleus, e.g. Bodek-Ritchie prescriptionprescription

• Resonance, Resonance, pp→→--pp (low Q (low Q22, , W) W) – Poorly measured and only 1st Poorly measured and only 1st

resonance described by Rein and resonance described by Rein and Seghal Seghal

• Deep Inelastic, Deep Inelastic, pp→→--X (high QX (high Q22, , W)W)– well measured by high energy well measured by high energy

experimentsexperiments– well described by quark-parton well described by quark-parton

model (pQCD with NLO PDFs)model (pQCD with NLO PDFs)– but doesn’t work well at low Qbut doesn’t work well at low Q2 2

region.region.

(e.g. SLAC data at Q(e.g. SLAC data at Q22=0.22)=0.22)• Issues at few GeV Issues at few GeV ::• Resonance production and Resonance production and

low Qlow Q22 DIS contribution meet. DIS contribution meet.• The challenge is to describe The challenge is to describe

ALL THREE processes atALL THREE processes at ALL ALL neutrino (or electron) neutrino (or electron) energiesenergies

• HOW CAN THIS BE DONE?HOW CAN THIS BE DONE?• QPM model with proper QPM model with proper

scaling behavior above 1scaling behavior above 1stst resonance using ideas from resonance using ideas from quark-hadron dualityquark-hadron duality

at x = 1

(quasi)elastic

F2 integral=0.43


Does model work?Does model work?• Can test in electron Can test in electron

scatteringscattering– Data at right Data at right predictedpredicted by fit by fit

• More complicated in More complicated in neutrino charged-currentneutrino charged-current– Isospin selection, e.g., Isospin selection, e.g., pp→→++++

• EOI considered by FNAL PACEOI considered by FNAL PAC– Collaboration (FNAL, Hampton, Collaboration (FNAL, Hampton,

Jefferson Lab, Rochester) being Jefferson Lab, Rochester) being formedformed

– Note that this project requires Note that this project requires a JHF 280m type detectora JHF 280m type detector• Is NUMI our test beam?Is NUMI our test beam?

Q2= 0.07 GeV2

Q2= 15 GeV2 Q2= 25 GeV2

Q2= 3 GeV2Q2= 9 GeV2

Q2= 1. 4 GeV2

Ref: Bodek and Yang hep-ex/0203009Ref: Bodek and Yang hep-ex/0203009

Q2= 0.22 GeV2


Fine-Grained Detector Fine-Grained Detector GoalsGoals• Observe recoil protonsObserve recoil protons

– Important for Important for nn––pp, , nn––pp00

– Investigate n capture layers?Investigate n capture layers?

00 , , –– reconstruction reconstruction– Adds a lot of mass. Muon charge needed Adds a lot of mass. Muon charge needed

for for

• Oxygen-rich TargetOxygen-rich Target– Water miscible scintillator layersWater miscible scintillator layers

• Exists. Commercially available. Need detailed study of Exists. Commercially available. Need detailed study of propertiesproperties

• Light output problematic? VLPC readout?Light output problematic? VLPC readout?

– Sampling water + plastic scint?Sampling water + plastic scint?– Acrylic? Is it stable? Lowish oxygen contentAcrylic? Is it stable? Lowish oxygen content


Fine Grained Location: Off-Fine Grained Location: Off-AxisAxis• Narrow band beam, similar to far Narrow band beam, similar to far

detectordetector– NBB crucial for study of cross-sections, NBB crucial for study of cross-sections,

particularly for neutral currentparticularly for neutral current•Event cannot be fully reconstructed Event cannot be fully reconstructed

without knowing Ewithout knowing E

– EE can be varied by varying position can be varied by varying position

• Bonus: can check beam spectrum, Bonus: can check beam spectrum, particularly backgrounds for particularly backgrounds for →→ee

– Not clean as in case of “2km” detectorNot clean as in case of “2km” detector


Event Spectra in Event Spectra in Near Off-Axis, Near Off-Axis, Near On-AxisNear On-Axis and and Far DetectorsFar Detectors at at

NUMINUMI

Far 0.7o OA Far 0.7o OA

Near 0.7o OA (LE)

Near 0.7o OA (ME)

Near On-Axis (LE)

Near On-Axis (ME)


NUMI EOI (technology NUMI EOI (technology test?)test?)• Ideal locations in NUMI tunnel Ideal locations in NUMI tunnel

complex exist for 2.5 GeV beamcomplex exist for 2.5 GeV beam– 1.5 GeV possible. 1 GeV tough.1.5 GeV possible. 1 GeV tough.

Locate in access drift


Conceptual NUMI Near Conceptual NUMI Near DetectorDetector

Active scintillator strip target

Active/passive frame around target

fine-grained near detector(s) at jhf: purpose and thoughts

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