# Presentation: 134194

## Three outstanding questions ~ 2003

-  Neutrino mass pattern:        This ?               Or that?

-  Electron component of 3 (sin2213)

-  Complex phase of s  CP violation in a neutrino sector  (?) baryon number of the universe

## The key:   e oscillation experiment

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

## Detector for the off-axis experiment

- Goal: Detect and identify interactions of electron neutrinos
- Neutrinos have small interaction cross section – need large mass detector (50 000 ton?)
- Neutrino flavor identification – via the charged lepton (electron/muon)  Charged Current (CC) interactions
- Search for e appearance – need to identify electrons with high efficiency

- Adam Para
- NSF
- March 4, 2003

##  e Appearance Experiment: a Primer

- _Systematics:_
- Know your expected flux
- Know the beam contamination
- Know the NC background*rejection power (Note: need to beat it down to the level of ne component of the beam only)
- Know the electron ID efficiency

- Detector performance :
- – identification efficiency
-   – background rejection

##  CC e and NC interactions 

- Low energy neutrinos ~ 2 GeV

- Relatively simple, low multiplicity events, no hadronic showers 

- Signal: electron (showering) track

-  Background: neutral current 0 production

- Simple events
- Topological information

## NuMI Off-axis Detector(s) Challenge

-  Surface (or light overburden)
- High rate of cosmic ’s
- Cosmic-induced neutrons
- But:
- Duty cycle 0.5x10-5
- Known direction
- Observed energy > 1 GeV

- Principal focus: electron neutrinos identification
-  Good sampling (in terms of radiation/Moliere length)
- Large mass:
-  maximize mass/radiation length
-  cheap absorber and detectors

## Backgrounds Summary

- e component of the beam
- Constrained by  interactions observed in the near MINOS detector ()
- Constrained by  interactions observed in the near MINOS detector ()
- Constrained by pion production data (MIPP)
- NC events passing the final analysis cuts (0?)
- 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 sec beam gate

- Backgrounds are small and under experimental control
- Do not depend (much) on the specific detector technology

## 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
- Split the money to maximize the product, rather than individual components

## e identification/background rejection: beam + detector issue

- e background

- NC (visible energy), no rejection

- Spectrum mismatch: These neutrinos contribute to background, but no signal

******e** (|Ue3|2 = 0.01)

- NuMI off-axis  beam makes the experimental challenge relatively easy (compared to the on-axis experiment):
-  bigger oscillation signal
-  smaller e component of the beam
- Lower neutral current background

## A conceptual design of a nue  detector

- Low Z tracking calorimeter

- Issues:
-  absorber material (_Particle board?_ OSB? Water?Other? )
- longitudinal sampling (__X0)?
- What is the detector technology (_RPC?_  Drift tubes? Solid scintillator? Liquid scintillator?)
- Transverse segmentation 2? _3?_ 4? 5? cm
- Monolithic? Modular? _Containerized?_ detector

- Well established detector technologies applicable
- Engineering and cost the principal challenges

## The fundamental issue: low cost detector

- Use standard materials whenever possible:
- Float glass
- Particle board
- Insulation boards
- Shipping containers
- Use industry standard dimensions (like 20’, 4’x8’) to minimize customized production
- Modular design to minimize installation/integration effort
- Robust technology to minimize environmental requirements (temperature, pressure, humidity)
- Detector-building interplay: use detector as a structural support for the building?

## Constructing the detector ‘wall’

- Containment issue: need very large detector. Recall: K2K near detector – 1 kton mass, 25 tons fiducial, JHF proposal – 1 kton mass, 100 tons fiducial
- Engineering/assembly/practical issues

- Solution: Containers ?

- Build a modular detector !

## On the importance of being mobile:mammals vs dinosaurs? 

- Move the detector to new locations/facilities as indicated by the initial results?

- Sin2213=0.05

## An example of a  possible detector: glass RPC (Belle) + particle board

- Glass resistive plate chamber (almost a spark chamber)  large signal (streamer) generated by a charge particle
- Inductive strip readout (for example home insulation boards with one side cut into strips)

**Notes:**
Check numbers of each type – need design parameter book

## Assemble absorber/detector modules into a container

## Conclusions

- We have a superb neutrino beam. Just need a detector(s).
- Relatively simple, off-the-shelf detector is sufficient to exploit the physics potential of the NuMI beam.
-  Detector size ( cost) is the primary challenge
-  Initial cost estimates 1-3 M$/kton   50-150 M$ for 50 kton detector
- Good ideas and a lot of engineering  necessary to develop a _credible_ design and cost estimate. Room for new developments.