# Presentation: 014180

## The Nuance NeutrinoMonte Carlo:Present Status and Future Plans

- D. CasperUniversity of California, Irvine

## Brief History

- Originally developed (ca. 1989) for IMB experiment
- Essentially rewritten in 1997-98 forSuper-Kamiokande
- Attempt at more universal interface, extended functionality
- Note: not official Super-K Monte Carlo
- First public release (v2) Summer 2002(hep-ph 0208030)
- Adopted (or plans to adopt) by:
- MiniBooNE
- SNO (atmospheric analysis)
- MINOS (upward-going muons)

## Physics Model: Quasi-Elastic

- Uses vanilla Smith-Moniz relativistic Fermi gas calculation
- kF = constant
- Fixed potential
- Agrees well with e-scattering and K2K FGD data (for leptons)
- Recoil nucleons may have some problems due to hard p > kF cutoff

## Physics Model: Resonances

- Rein & Seghal (1979) model
- Interference of resonances (and non-resonant background), harmonic oscillator quark model
- Angular distribution of pions (in resonance rest frame) averaged
- Treatment of non-resonant background suspect
- Some evidence of disagreement with K2K near detector data at smallest |Q2| ~ 0

## Work in Progress: DIS

- Goal: Implement Bodek & Yang ’03 DIS model (using GRV 98 pdf’s)
- Standalone B&Y prototype program (including event generation with PYTHIA) now working
- Still needs to be integrated with Nuance
- PYTHIA interface (getting it to generate event with the scaling variables you tell it) has taken 90% of the tiime

## Hadronic Mass Comparison

## Q2 Comparison

## Scaling Variable (w)

## Work in Progress: Rein ’87 Model

- Trying to implement Rein ’87 resonance model in standalone prototype
- Similar to R&S ‘79, main difference is non-resonant background
- Also get pion angular distribution
- See if Q2 agrees with Rein 79
- So far, unable to get reasonable results
- Still trying to understand calculation – there seem to be contradictory equations
- Wrote to Rein, but response doubtful (retired?)

## Other Features and Processes

- Many other bells and whistles included
- Coherent and diffractive pion production
- Use Rein-Seghal models
- Little data at low energies, low-A
- Final state interactions in Oxygen nucleus
- Need to add formation zone logic
- Upward-going muons
- A. Habig developing new muon propagation model
- Proton decay, supernovae, 3-neutrino oscillation, etc
- Low priority

## Future Plans: Interface

- Present interface, while powerful for experts, is poorly documented, clunky and intimidating for new users
- ZEBRA (TZ) based
- Needs a manual desperately
- Problem: how to preserve flexibility while making program more accessible?
- KUIP-based (PAW-like) interface?
- Compatibility with GEANT (geometry/materials) would also be desirable

## Availability

- Posted on the web at:
- _[http://nuint.ps.uci.edu/nuance](http://nuint.ps.uci.edu/nuance)_
- Automated install script
- Runs on L/unix or Windows

## Next Major Release

- A new major release (v3) is planned for the Spring:
- Bodek & Yang 2003 DIS Model, GRV pdf’s
- Improved parton shower/fragmentation; eliiminate LEPTO
- Include EMC effect
- Improved Resonant/DIS connection
- How to accomplish still unclear...
- Rein 87 resonance model
- Pion angular distribution included
- Improved treatment of non-resonant background
- N channel
- Improved muon propagation for upward mu’s (A. Habig)
- Formation zones (?)
- Clean-up of obsolete code, many minor improvements

## Features Still Missing in v3

- A user manual
- A better interface (KUIP based?)
- Cleaner, ZEBRA-free coding
- Would require rewriting in a different language (Fortran 90, C++, ???)
- Electron beams
- Getting closer, though
- A high priority for the following release
- More general (non-Oxygen) nuclear FSI
- FLUKA would be clear choice, once made public

## Comments

- From generator point of view, H2 and D2 targets are essential
- Modeling of nuclear targets based on free nucleons
- From LBL/Proton Decay point of view, O2 target also seems very worthwhile
- Focus on target materials actually used in real world: O, Ar, Fe, ???
- 0, K, proton, and 2- measurements also vital
- Very limited existing data
- Important backgrounds to current and future experiments