Flux-Tool

This package reads neutrino flux universes produced by Package to Predict the Flux (PPFX), and extracts a neutrino flux prediction with corresponding uncertainties. All analysis products are output to a .root file specified in a config.toml. The package will also produce figures as pdf, png, and a .tex, for the majority of the products stored in the ROOT file.

Prerequisites

Before you begin, make sure you have the following prerequisites installed:

• Python 3.11 or later: Visit the official Python website at https://www.python.org/downloads/ to download and install the latest version of Python.
• ROOT 6.28 or later: Flux-Tool requires ROOT/PyROOT version 6.28 or later. You can obtain ROOT from the official ROOT website at https://root.cern/install/.

Installation

Flux-Tool is available for installation from PyPI, the Python Package Index. Follow the steps below to install the project:

1. Open your terminal or command prompt.

2. Create a virtual environment (optional but recommended):

   $ python -m venv .venv

3. Activate the virtual environment:

   $ source .venv/bin/activate

4. Install Flux-Tool using pip:

   $ pip install flux-tool

Usage

Modify the config.toml file to specify the input files and other analysis parameters.

$ flux_tool -h
usage: flux_uncertainties [-h] [-c CONFIG] [-p PRODUCTS_FILE] [-v] [-z] [--example-config]

This package coerces PPFX output into a neutrino flux prediction with uncertainties, and stores various spectra related to the
flux, e.g., fractional uncertainties, covariance matrices, etc.

options:
  -h, --help            show this help message and exit
  -c CONFIG, --config CONFIG
                        specify the path to a toml configuration file
  -p PRODUCTS_FILE, --plots-only PRODUCTS_FILE
                        Specify path to an existing ROOT file for which to produce plots
  -v, --verbose
  -z, --enable-compression
                        Enable compression of the output plots directory
  --example-config      Print an example configuration file

Alternatively, this package can be imported directly:

import flux_tool

See example_nb.ipynb for a demonstration of how to use the package.

Contents of the Output ROOT File

beam_samples

If provided to flux_tool, copies of the systematically altered neutrino flux samples, including the nominal, are stored here.

beam_systematic_shifts

Fractional shifts from the nominal, calculated for each flux sample in beam_samples.

covariance_matrices

Contains all covariance and correlation matrices, organized into two subdirectories: one for hadron effects and another for beam effects (if applicable). Each covariance matrix is stored in 2 forms:

1. TH2D (prefixed hcov_ or hcorr_)
2. TMatrixD(prefixed cov_ or corr_) Covariance matrices with the _abs suffix are in absolute units of the flux, whereas those without the suffix are normalized the PPFX universe mean, in the case of hadron systematics, or to the nominal beam run, in the case of the beam line systematics. Each bin is labeled according to the combination of horn polarity, neutrino flavor, and energy bin number, e.g., fhc-nue-1.

flux_prediction

This directory holds a set of TH1D for each neutrino mode. The flux value is extracted as the PPFX mean, while the uncertainties incorporate statistical, hadron systematic, and beam line systematic (if applicable) uncertainties.

fractional_uncertainties

This directory contains two subdirectories, beam and hadron, containing the fractional contributions to the flux uncertainty for each effect.

pca/

This directory houses the outputs of the Principal Component Analysis of the hadron covariance matrix.

• eigenvectors/hevec_* Unit eigenvectors
• principal_components/hpc_* principal components scaled by the square root of the corresponding eigenvalue and transposed into bins of neutrino energy
• hcov_pca reconstructed hadron covariance matrix used for validation purpose.
• heigenvals Each bin of this histogram (TH2D) holds the eigenvalues extracted from the PCA
• heigenvals_frac same as the previous, but each eigenvalue is divided by the sum of all eigenvalues such that each eigenvalue is represented as its contribution to the total variance.

ppfx_corrected_flux

Directory containing the PPFX-corrected neutrino spectra. These histograms are produced by calculating the means and sigmas of the flux distributions across the 100 universes contained in ppfx_output.

ppfx_flux_weights

Directory containing TH1D for each horn-neutrino flavor combination, the bins of which contain weights that can be used to apply the PPFX flux correction.

ppfx_output

Contains the original output received from PPFX, organized into two subdirectories corresponding to Forward Horn Current (FHC) and Reverse Horn Current (RHC). Each contains a nom subdirectory which holds the nominal (uncorrected) neutrino flux vs. energy spectrum, hnom_nu*, in addition to the PPFX central value, hcv_nu. Spectra broken down by parent hadron can be found under the parent subdirectory. The remaining subdirectories hold the universes for each hadron production systematic:

statistical_uncertainties

Directory containing statistical uncertainties for every horn-neutrino flavor combination. Histograms with the suffix _abs are in absolute units of the flux, and those without the suffix are in the fractional scale. The two matrices, hstatistical_uncertainty_matrix and statistical_uncertainty_matrix, are diagonal TH2D and TMatrixD, respectively, organizing the statistical uncertainties into a useful form to be added with covariance matrices.

corr_total

TMatrixD correlation matrix incorporating all sources of uncertainty

cov_total_abs

TMatrixD covariance matrix in units of the flux, incorporating all sources of uncertainty

hcorr_total

TH2D correlation matrix incorporating all sources of uncertainty

hcov_total_abs

TH2D covariance matrix in units of the flux, incorporating all sources of uncertainty

matrix_axis

TAxis with the binning and labels of all matrix axes

xaxis_variable_bins

TAxis containing the binning applied to all spectra w.r.t. $E_\nu$ in GeV.