# Presentation: 661526

## Event Simulation in a Close-In Detector for the BNL Long Baseline Experiment

- Steve Kahn
- 31 Jan 2003

- Jan 31, 2003

## Requirements for a Close-in Detector for the Long Baseline Neutrino Experiment

- This detector should provide flux distributions as a function of E.
- It should provide flux distributions for all components:   e   e
- A magnetic field is desired to distinguish the sign of the leptons.
- The detector should provide a flux that can be extrapolated to the far detector.
- The most desirable case would be to position the close detector such that the neutrino source position looks like a point.
- This would suggest that the close-in detection should be placed greater than 2 km from the target.  This is not easily achievable for a beam inclined 11.3o.

- Jan 31, 2003

## Technology to be used for the Close Detector

- It would be desirable to have neutrino interactions off the same nuclei at the near and far detector.
- There are nuclear effects such as pion reabsorption.
- A resonance event pp can look like np in an Ar detector but not in a H2O detector.
- There are Fermi Motion effects that would be different with different nuclear targets.
- There different resolutions with different detectors.
- One needs to evaluate the size of these effects.  There are likely to cause ~10% errors in the knowledge of the beam flux at the far detector.
- We might be able to live with it.

- Jan 31, 2003

## Cartoon Design of the Close-In Detector

- 3 meters

- 1.5 m

- 2 meters

- Jan 31, 2003

## Liquid Argon Detector

- The major component of this detector is a magnetized liquid argon TPC detector modeled after that proposed in the -LANNDD experiment.
- I have chosen as a start the dimensions of -LANNDD:
- 223.0 m3
- These dimensions can be increased to enclose the growth of transverse showers.
- I have assumed a 0.5 Tesla vertical field on the liquid argon.
- This detector would have 17 tons of liquid argon.

- Jan 31, 2003

## Ice Target

- In order to address the criticism that the near detector has a different target than the far detector, a supplementary target made of *ice *could be put in front of the *liquid argon* to provide a sample of events that interacted on water.
- The *ice *would not have active detection.  Events would observed as tracks from an interaction upstream.
- An upstream veto detector would be necessary to verify that the interaction occurred in the *ice.*
- I have assumed about 0.5 meters of ice which would give 0.22 tons of target.

- Jan 31, 2003

## Muon Magnet

- Liquid Argon has interaction84 cm.  This would provide on average ~2 interaction lengths to distinguish pions from muons.  An external magnetized iron-scintillator detector could verify muons and provide a measurement of the muon momentum.
- The field in the iron is sort of torroidal, à la Minos.
- The magnet in the liquid argon only provides the momentum projected in a plane.

- Jan 31, 2003

## 300 MeV +

- Jan 31, 2003

## 1 GeV +

- Jan 31, 2003

## Another 1 GeV +

- Jan 31, 2003

## 2 GeV +

- Jan 31, 2003

## Another 2 GeV +

- Is there momentum information from the field in the iron or are we seeing multiple scattering?  2 GeV muon is contained in the Fe

- Jan 31, 2003

## 3 GeV +

- 3 GeV  punches through 1.5 m of Fe

- Jan 31, 2003

## 300 MeV e+

- Jan 31, 2003

## Another 300 MeV e+

**bremsstrahlung**

- Jan 31, 2003

## 1 GeV e+

- Jan 31, 2003

## 2 GeV e+

- Some energy would be lost in the Iron and would not be seen if used as a calorimeter.  Can one measure the energy from curvature?  Not clear.

- Jan 31, 2003

## 3 GeV e+

- Jan 31, 2003

## 300 MeV o

- Clean separation of gammas

- Jan 31, 2003

## 1 GeV o

- Difficult to separate gammas in this event

- Jan 31, 2003

## Another 1 GeV o

- Two gammas separate cleanly in this event

- Jan 31, 2003

## 2 GeV o

- Can I distinguish this from an electron?

- Jan 31, 2003

## Blowup of Vertex Region of Previous Event

- Is this the second gamma?

- Jan 31, 2003