Regular Series


Vol. 40 (2009), No. 9, pp. 2379 – 2670

45th Winter School in Theoretical Physics Neutrino Interactions: From Theory to Monte Carlo Simulations

Ladek-Zdrój, Poland; February 2–11, 2009

How Much Nuclear Physics Do We Need to Understand the Neutrino Nucleus Cross-Section?

abstract

Over the past two decades, electron scattering experiments have clearly exposed the limits of the independent particle model description of atomic nuclei. I will briefly outline the dynamics leading to the appearance of strong correlation effects, and their impact on the electroweak nuclear cross-sections in the impulse approximation regime.


Overview of Neutrino–Nucleus Interactions

abstract

Neutrino–nucleus reactions are surveyed. The approximations usually made are identified and a comparison to the corresponding electron–nucleus processes is presented. Impulse Approximation (IA), factorization of the cross-section and scaling approaches (SA) to lepton–nucleus scattering are examined in detail.


Experimental Measurements of Neutrino Cross-Sections Near 1 GeV

abstract

We summarise recent neutrino and antineutrino measurements near 1 GeV by the K2K, MiniBooNE and SciBooNE collaborations. We focus on experimental methods and note discrepancies between the most commonly used models for neutrino–nucleus interactions and recent high statistics observations of charged-current quasi-elastic scattering as well as charged and neutral current pion production on carbon and oxygen. We discuss possible directions for future measurements.


Final State Interactions in Neutrino–Nucleus Experiments

abstract

Many neutrino–nucleus experiments need to find quasifree events in order to measure the beam energy which is an important part of oscillation measurements. Final state interactions are very important because they can mask the topology of an event. This paper reviews some of the concepts important in a good final state model and provides some detail for what is used in GENIE.


The GENIE Neutrino Monte Carlo Generator

abstract

The exploration of the neutrino mixing matrix forms one of the major directions in science. A number of scientific opportunities lie ahead: Over the next decade searches for \({\nu }_{\mu } \rightarrow {\nu }_{e}\) oscillations will dramatically improve our sensitivity to \({\theta }_{13}\), potentially opening a window to exploring CP violation in the lepton sector. Precision measurements of \({\theta }_{23}\) from high statistics \({\nu }_{\mu }\) disappearance studies will shed more light on the neutrino mixing matrix and, possibly, elucidate its relation with the quark mixing matrix. Over a similar time-scale, exploiting matter effects, we will probe the neutrino mass hierarchy. Much of the research program will be carried out with accelerator-made neutrino beams in the few-GeV energy range, the challenging boundary between the non-perturbative and perturbative regimes where our lacking physics descriptions are now being exposed by increasingly precise neutrino data. Advancing our understanding of fundamental neutrino properties, will require building a more complete picture of neutrino interactions and reducing the corresponding systematics to the \(\sim \) 1% level. This will pose a series of important theoretical and experimental challenges. Neutrino generators, the interface between theory and experiment, are in the core of this effort. The 45th Winter School in Theoretical Physics at Lądek-Zdrój was a unique event in the effort to improve neutrino interaction descriptions. Secluded in the Polish countryside, inquiring students, the authors of mainstream neutrino generators representing many experimental communities, and leading theorists had the opportunity to delve into modeling issues, question physics assumptions and probe the accuracy of neutrino simulations. This was a very instructive experience for everyone involved. The goal of this brief note is to refresh the students on some of the physics and technical points discussed during the GENIE lectures.


A Neutrino Interaction Simulation Program Library NEUT

abstract

A neutrino interaction simulation program library NEUT has been developed for the studies of the atmospheric neutrino and the accelerator neutrinos. In this article, the models and the implementations of neutrino interactions in NEUT are described. Also, the nuclear effects of generated particles are discussed.


Neutrino Interactions with fluka

abstract

A new neutrino interaction generator has been developed in fluka. The package, called nundis (NeUtrino–Nucleon Deep Inelastic Scattering), is specifically built in order to be fully integrated with the hadronization and nuclear models of the fluka Monte Carlo code which were already successfully tested in hadronic interactions. This generator thus complements the already existing generator of quasi-elastic neutrino scattering. Here we describe the physics, sampling methods, and other specifics of nundis, as well as the limitations of the code.


Running NuWro

abstract

The NuWro Neutrino Event Generator developed by the Wrocław Neutrino Group (WNG) is lightweight but full featured. It handles all interaction types important in neutrino–nucleus scattering as well as DIS hadronization and intranuclear cascade. Its input file, by default params.txt, is a plain text file and the output file, by default eventsout.root, is a root file which can be analyzed by means of the included myroot program, or by standard root, after loading supplied dictionary library event1.so.


Running Nuance

abstract

This article describes version 3.006 of Nuance, an advanced and freely available neutrino generator written by Dave Casper of University of California, Irvine. Source codes of the program are publicly available. This description is based on Dave Casper’s article “The Nuance Neutrino Physics Simulation and the Future”, http://nuint.ps.uci.edu/nuance/files/nuance_nuint01.pdf , Nuance website at http://nuint.ps.uci.edu/nuance/ , README.txt file provided in the src folder of Nuance distribution, and my own experience as a Nuance user.


all authors

M. Antonello, V. Caracciolo, G. Christodoulou, J. Dobson, E. Frank, T. Golan, V. Lee, S. Mania, P. Przewlocki, B. Rossi, D. Stefan, R. Sulej, T. Szeglowski, R. Tacik, T. Wachala

Study of Pion Production in \(\nu _{\mu }\) CC Interactions on \(^{16}\)O Using Different MC Generators

abstract

In this report we present simulated event numbers, for various MC generators, for pion production in \(\nu _{\mu }\) CC reactions on \(^{16}{\rm O}\). For the simulation we used four different neutrino interaction generators: GENIE, FLUKA, NEUT, and NuWro, as proposed during the 45th Karpacz Winter School on neutrino interactions. First, we give a brief outline of the theoretical models relevant to pion production. We then present results, in the form of tables showing the occupancy of primary and final state pion topologies, for all the generated samples. Finally we compare the results from the different generators and draw conclusions about the similarities and differences. For some of the generators we explore the effect of varying the axial mass parameter or the use of a different nuclear model.


Covariant Density Functional Theory: Inclusive Charged Current Neutrino–Nucleus Reactions

abstract

Covariant Density Functional Theory (CDFT) is used to investigate inclusive neutrino–nucleus cross-sections. The ground state of the even–even nucleus \((N,\,Z)\) is obtained as the static solutions of the Relativistic Hartree–Bogoliubov (RHB) equations and the final states of the odd–odd nucleus \((N-1,\,Z+1)\) as well as the relevant transition probabilities are calculated in the Relativistic Quasiparticle Random Phase Approximation (RQRPA). The weak lepton–hadron interaction is expressed in the standard current–current form.


Low Energy Neutrino Scattering: From Fundamental Interaction Studies to Astrophysics

abstract

Neutrino scattering at low energies is essential for a variety of timely applications potentially having fundamental implications, e.g. unraveling unknown neutrino properties, such as the third neutrino mixing angle, the detection of the diffuse supernova neutrino background, or of cosmological neutrinos and furnishing a new constraint to 2\(\beta \) decay calculations. Here we discuss some applications, the present status and the perspectives.


Coherent Neutrino Scattering

abstract

We present a microscopic model for coherent pion production off nuclei induced by neutrinos. This model is built upon a model for single nucleon processes that goes beyond the usual \({\mit \Delta }\) dominance by including non resonant background contributions. We include nuclear medium effects: medium corrections to \({\mit \Delta }\) properties and outgoing pion absorption via an optical potential. This results in major modifications to cross-sections for low energy experiments when compared with phenomenological models like Rein–Sehgal’s.


Modeling Neutrino–Nucleus Interactions in the Few-GeV Regime

abstract

We present calculations for quasi-elastic inclusive neutrino-induced nucleon knockout reactions on atomic nuclei. Final-state interactions (FSI) are introduced using a relativistic multiple-scattering Glauber approximation (RMSGA). For interactions at low energies, long-range correlations are implemented by means of a continuum random phase approximation (CRPA) approach.


\(C_5^A\) Form Factor from ANL Experiment

abstract

\(C_5^A(Q^2)\) axial form factor is extracted from the ANL neutrino–deuteron scattering data with deuteron structure effects taken into consideration. The best fit of the \(C_5^A(Q^2)\) axial form factor is obtained assuming dipole parametrization with \(C_5^A(0)=1.13\pm 0.15\) and \(M_A=0.94\pm 0.08\) GeV.


One Pion Production in Neutrino Induced Reactions

abstract

We investigate neutrino interactions with nucleons and nuclei, paying special attention to 1-pion production reactions. The elementary neutrino–nucleon cross-section is presented as the sum of the leading Delta-pole diagram and several background diagrams calculated within the non-linear sigma-model. Neutrino interactions with nuclei could then be treated within the GiBUU transport model that takes into account various nuclear effects.


Quasi-Elastic Charged-Current and Neutral-Current Neutrino–Nucleus Scattering in a Relativistic Approach

abstract

Relativistic models developed for the exclusive and inclusive Quasi-Elastic (QE) electron scattering have been extended to Charged-Current (CC) and Neutral-Current (NC) \(\nu \)-nucleus scattering. The results of different descriptions of Final-State Interactions (FSI) are compared.


Hadronic Transport Approach to Neutrino–Nucleus Scattering: the Giessen BUU Model and Its Validation

abstract

We present the GiBUU model for neutrino–nucleus scattering (\(\nu \)GiBUU): assuming impulse approximation, this reaction is treated as a two step process. In the initial state step, the neutrinos interact with bound nucleons. In the final state step, the outgoing particles of the initial reaction are propagated through the nucleus and undergo final state interactions. In this contribution, we focus on the validation of the initial and final state interaction treatment in GiBUU using experimental data for pion–nucleus, photon–nucleus and electron–nucleus scattering.


Single Pion Production. Theoretical Dependencies and Experimental Limitations

abstract

The \(\pi ^0\) production in NC interactions of \(\nu _\mu \) constitutes one of the main backgrounds in \(\nu _e\) appearance measurements of modern long baseline neutrino experiments. This work presents cross-section uncertainty estimates in the context of T2K experiment. The contribution from uncertainty in form factors was found to be at the level of 10%. Additionally, visibility of different \(\pi \) production channels in T2K detectors is examined to verify to what extent T2K itself can measure \(\pi \) production cross-sections.


Validating Monte Carlo

abstract

A simple model of the \(^{16}\)O\((\pi ,\pi ')\) quasifree scattering reaction is presented, and compared to experimental data. The model incorporates the same features as Monte Carlo neutrino generators for the CCQE reaction.


Event Generator Validation and Systematic Error Evaluation for Oscillation Experiments

abstract

In this document I will describe the validation and tuning of the physics models in the GENIE neutrino event generator and briefly discuss how oscillation experiments make use of this information in the evaluation of model-related systematic errors.


Propagating \(\nu \)-Interaction Uncertainties via Event Reweighting

abstract

We present an event reweighting scheme for propagating neutrino cross-section and intranuclear hadron transport model uncertainties which has been developed for the GENIE-based [C. Andreopoulos et al., arXiv:0905. 2517[hep-ph]] neutrino physics simulations. We discuss the motivations, implementation and validation of the scheme and show an example application where it is used to evaluate the associated systematic uncertainties for neutral current \(\pi ^{0}\) production.


Experimental Implications on Neutrino Cross-Sections Around 1 GeV

abstract

The next generation of oscillation neutrino experiments require more and more precise measurements of the properties of neutrino interactions with matter. This article summarizes the challenges of the new frontier experiments.


A Review of Long-Baseline Neutrino Oscillation Experiments

abstract

In this paper, I will review the status of current and planned accelerator-based long-baseline neutrino oscillation experiments which are sensitive to the oscillation parameters associated with the atmospheric neutrino mass-scale, and are designed to precisely determine the parameters of the PMNS neutrino mixing matrix.


The Liquid Argon TPC Technology for Precise (Quasi-Elastic) Neutrino Cross-Sections Reconstruction

abstract

Precise measurements and modeling of the \(\nu \)-nucleus cross-section in the intermediate energy range (\(\sim \) 0.5–5 GeV), and related nuclear effects, are today considered as fundamental issues for a robust control of the systematic uncertainties in the forthcoming experimental effort aiming at precision measurements of the MNSP matrix elements. The LAr TPC technology is ideal to perform a wide variety of \(\nu \)-physics studies in the intermediate energy range, thanks to the capability of single particle identification and detailed reconstruction of exclusive topologies. The ArgoNeuT detector, recently put into operation on the low energy NuMI beam line at FNAL, may provide with first data and precision measurements of quasi-elastic \(\nu \)–Ar cross-section.


MINER\(\nu \)A

abstract

The world is entering an era of precision neutrino measurements. This requires a precise knowledge of cross sections, final states, and nuclear effects. Neutrino cross sections are poorly known, with a \(\sim 20\) to 100 percent total error [G. Sam Zeller, private communication]. There also exist unresolved discrepancies in various cross section and nuclear effects measurements. \({\mathrm {MINER}\nu \mathrm {A}}\) [http://minerva.fnal.gov/] is an accelerator-based neutrino experiment, located at Fermi National Accelerator Laboratory, United States. \({\mathrm {MINER}\nu \mathrm {A}}\) is designed to perform cross section and nuclear effects measurements with unprecedented accuracy, reducing the current errors to 5 to 20 percent total. These measurements are vital for upcoming and planned experiments such as T2K [http://jnusrv01.kek.jp/public/ t2k/], NoVA [D. Ayres, hep-ex/0503053], and DUSEL [http://www.int. washington.edu/DUSEL/]. No other experiment exists or is planned that will be able to perform these measurements in the \({\mathrm {MINER}\nu \mathrm {A}}\) energy range. \({\mathrm {MINER}\nu \mathrm {A}}\) is in the final stages of construction, and will begin taking data in early 2010.


Neutrino Cross-Section Measurements at the Spallation Neutron Source

abstract

In this paper we discuss the proposal to build a neutrino facility at the recently-completed Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory (ORNL). This facility can host an extensive, long-term program to study neutrino–nucleus cross-sections in the range of interest for nuclear astrophysics and nuclear theory.


Recent Results from SciBooNE

abstract

SciBooNE is a neutrino experiment measuring the neutrino cross-sec- tions on carbon in the one GeV region. In this paper, we discuss the mea- surement of charged current coherent pion production on carbon by neutrinos.


Liquid-Argon Time Projection Chambers in the U.S.

abstract

Liquid Argon Time Projection Chamber (LAr TPC) detectors are ideally suited for studying neutrino interactions and probing the parameters that characterize neutrino oscillations. The ability to drift ionization particles over long distances in purified argon and to trigger on abundant scintillation light allows for excellent particle identification and triggering capability. Recent U.S. based work in the development of LAr TPC technology for massive kiloton size detectors will be discussed in this talk, including details of the ArgoNeuT (Argon Neutrino Test) test-beam project, which is a 175 liter LAr TPC exposed to Fermilab’s NuMI neutrino beamline.


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