Solar delta-m squared Oscillations using an Off-axis beam to DUSEL - - PowerPoint PPT Presentation

Solar delta-m squared Oscillations using an Off-axis beam to DUSEL

September 16th, 2006 Robert Davis University of Colorado

Goals

• Perform first terrestrial measurement of solar

parameters using neutrinos (not anti-neutrinos)

– By use of Long Baseline Accelerator Experiment

• Can you improve the delta-m2 measurement beyond

current understanding?

• Develop sensitivity to theta23 octant

Considerations

• Use off axis flux to isolate lower energies
• Looking for an effect that is at lower energy than

delta m2

23

• See if it is possible to distinguish between theta12

and theta13

Physical Equation

P(υµ −> υe) = sin2(2θ12)∗sin2(m2

21L/(4E))*cos2(θ23)

m2

21L/(4E) << 1

P(υµ −> υe) ≈ sin2(2θ12)∗(m2

21L/(4E))2*cos2(θ23)

Therefore plot: cos2(θ23) vs sin2(2θ12)∗(m2

21L/(4E))2

Method

• Modified T2K Monte Carlo used for beam flux

– Geant 3

• GLOBES program used to calculate event spectra

– Will be used in the future to calculate sensitivities

• Construct sensitivity plots

Experiment Assumptions

• 2º Off Axis
• Baseline 1497km (FNAL to Henderson)
• Detector 300 kTon Water Cherenkov

– Performance modeled on existing SuperK

• 0.77 MW
• 5 year running time
• 40 Gev beam

Oscillation Parameters used: sin2(2θ12) = 0.8 sin2(2θ23) = 1 m2

21 = 7e-5 eV2

m2

31 = 2e-3 eV2

cp = 0

2º Off Axis Beam Comparison at 1497km

• J-PARC flux
• ptimized for

½ to 1 GeV energies with small e and 0 backgrounds

• Taken as a starting

point, other fluxes will be examined

(No Oscillations)

2º Off Axis Beam Comparison 0 to 2 GeV window

Nue Appearance Event Spectra

• sin2(2θ13) = 0.1 (red)

– Total Events 17

• sin2(2θ13) = 0.0 (black)

– Total Events 10

Background Signal

• Experimental Parameters

–

2º Off Axis

–

Baseline 1497km

–

Detector 300 kTon Water Cherenkov

–

0.77 MW

–

5 year running time

–

40 Gev beam

Conclusions

• There are effects of the solar parameters at this

distance

• Statistics are too low to look at sensitivities

– Based on extremely conservative estimate of

background rejection, efficiency and beam flux

– Need to look at higher fluxes and variations of detector

parameters

Near Future

• Use WBLE flux at 1497km and 2º off axis to

examine solar parameters

• Include some of the new detector designs to get more

events

• Look at different off axis angles

– For example: 0.75º, 1º, 1.5º

• Generate sensitivity plots for the solar

parameters and cos(θ23)

– For example plot:

(m2

21*sin2(2θ12))2 vs sin2(2θ13)