# Presentation: 802781

## MiniBooNE StatusSteve BriceFermilab

- Overview
- Beam
- Primary Beam
- Secondary Beam
- Detector
- Calibration
- Triggering
- Neutrinos
- Summary

## The Collaboration

- Small experiment
- ~60 scientists
- 13 institutions

## Investigating LSND Result

- LSND:
- Excess of e events in a beam
- 87.9 ± 22.4 ± 6.0 over background
-  evidence for  oscillation

- To Check LSND you want
- Experiment with
- different systematics
- higher statistics
- similar L/E
-        MiniBooNE

## Why is the LSND Result Interesting?

- LEP measurement of Z width says...
- 3 light, active neutrinos
- Solar, atmospheric, and LSND neutrino measurements indicate...
-  3 different m2 scales
- Cannot get 3 m2 scales from 3 masses
- Some possible ways out...
- one or more results not due to oscillations
- add sterile neutrino(s)
- violate CPT

## Beam Overview

- Primary Beam
- 8 GeV protons from Booster
- Into MiniBooNE beamline
- Secondary Beam
- Mesons from protons striking Be target
- Focused by magnetic horn and monitored by LMC
- Tertiary Beam
- Neutrinos from meson decay in 50m pipe
- Pass through 450m dirt (and oscillate?) to reach detector

**Booster**

**Beamline**

**Target and Horn**

**LMC**

**Decay Region**

**450m dirt**

**Detector**

- Primary Beam
- (protons)

- Secondary Beam
- (mesons)

- Tertiary Beam
- (neutrinos)

## Booster Performance

- Booster has never worked this hard
- Steady increase in rate of delivered protons via ...
- Careful tuning
- Optimising rep rate and charge per pulse
- On 6 March set all time Booster record ...
- 5.7x1016 protons/hour
- Currently average ...
- 3-4x1016 protons/hour
- Need ~2-3 times higher rate to get to 1021 protons on target

- Energy Lost per Proton  (W-min/proton)

- Total   Booster Output (protons/min)

- Test run with L13 septum removed

- Notch shortened

- Labwide shutdown

- MiniBooNE turn on

## Future Booster Improvements

- Booster studies
- Recent physics staff increases and dramatic increase in involvement of Beam Physics Department
- Already paying off (e.g. septum dogleg beam losses)
- Collimation system
- Design almost complete
- Installation ~ June 1
- Large Aperture RF Cavities
- Increase aperture from 21⁄4” to 5”
- Powered prototype tested
- 2 vacuum prototypes being built for summer shutdown
- Propose to build whole new system (18 cavities + power supplies)

## MiniBooNE Beamline

- Phase I beam (intermediate dump)
- April 29 2002
- Phase II beam (multiwire instead of target)
- June 26 2002
- Phase III beam (final configuration)
- August 24 2002

- Beamline works well
- Beamline modelling works well

## Horn and Target Performance

- Protons impinge on 71cm long, air cooled Beryllium target
- Horn focusing of secondary beam increases  flux by factor of ~7
- 170 kA pulses, 143s long at ~5 Hz
- 200 million pulse design lifetime

- Horn stress tested with 10 million pulses in Nov-Dec 2001
- Installation completed June 2002
- Has performed flawlessly with ~11 million pulses in situ to date

## es from K decay are a major background
K decays produce wider angle muons than  decays

- K decays produce wider angle muons than  decays

- LMC muon spectrometer
- 7 degrees off axis
- Scintillating fibre tracker
- Currently scintillator paddles

- Little Muon Counters

- LMC triggered off beam-on-target signal
- Can see 53MHz beam microstructure

## Detector Overview

- 12m diameter sphere
- Filled with 950,000 litres of pure mineral oil
- Light tight inner region with 1280 8” PMTs (10% coverage)
- 240 PMTs in outer veto region
- Neutrino Interactions in oil produce
- Prompt Čerenkov light
- Delayed scintillation light

## Detector Construction

- Fully Complete April 2002
- Several months of shakedown and calibration prior to first beam

## MiniBooNE Particle ID

- Identify electrons (and thus candidate e events) from characteristic hit topology

- Michel e
- candidate

- Beam 
- candidate

- Beam 0
- candidate

## Laser Flask System

- 4 Flasks distributed about the tank

- Measure tube timing response (needed for event reconstruction)

- Measure tube charge response (needed for energy measurement)

## Muon Tracker and Cubes

- Muon tracker system
- Provides muons of known direction in the tank
- Key to understanding energy and reconstruction

- Scintillator cubes
- 7 throughout the tank
- Provides muons and Michel electrons of known position

- 

- e

## DAQ and Triggering

- Variety of triggers
- Laser
- Tracker and cube
- Strobe
- Beam
- Tank activity
- Understand detector response down to a few MeV

## Coarse BeamEvent Timing

- DAQ triggered on beam from Booster
- Detector read out for 19.2 s
- Neutrino pulse through detector lasts 1.6 s
- With a few very simple cuts non-neutrino/neutrino rate is  ~10-3

## A resistive wall monitor measures the beam time profile just before the target
Discriminated signal sent to DAQ for fine timing

- Discriminated signal sent to DAQ for fine timing

- Fine Beam Event Timing

- With ...
- Fitted event position
- Fitted event time
- RWM timing pulse
- we measure the booster bunch timing....
- in neutrinos!

## Energy Response

- Cosmic Michel Decays
- Used to set energy scale

**Cosmic Michel data**

**Analytic curve**

- 0 mass reconstruction
- In Beam Time window
- Tank hits > 200
- Veto hits < 6
- Both rings > ~60MeV

## Reconstruction: Charged Lepton Direction

- Fitted direction with respect to beam
- Tank hits > 200
- Veto hits < 6
- Fit radius < 500cm

## Reconstruction: Event Position

- Fitted position of the centre of the event track
- Cuts:-
- Tank hits > 200
- Veto hits < 6
- Fit radius < 500cm
- Cartesian coordinates scaled to give equal volume slices in a sphere

- Asymmetry from anisotropy
- of event directions + veto cut

- Rolloff at edges
- from veto cut

## Reconstruction: Energy

- Preliminary Visible Energy
- CUTS:-
- In beam time window
- Tank hits > 200
- Veto hits < 6
- Fitted radius < 450
- Flux falls in range of MC predictions
- HARP and E910 analyses will tighten prediction

## Summary

- All systems working well
- We're at 4% of 1021 protons on target
- Just need to continue improvement in beam.