SNOwGLoBES Tutorial Kate Scholberg Supernova Hack Days IV What is - - PowerPoint PPT Presentation

SNOwGLoBES Tutorial

Kate Scholberg Supernova Hack Days IV

What is SNOwGLoBES?

What it’s not: a Monte-Carlo simulation,

• r an event generator (like MARLEY)

It’s a mean event rate calculator for low-energy (<100-200 MeV) neutrino interactions: fast and simple and good for many studies, but does not replace a full MC It’s designed especially for supernova neutrinos, but will work for any flux in this energy range :

• is open source
• is available in github
• makes use of the front-end

(event rate calculation part) of GLoBES but does not do oscillation fits

SuperNova Observatories with GLoBES

History and status

• Development started in 2010

(contributions from many)

• Originally motivated by
• ld-LBNE water & argon studies

[still contains some relics from that era]

• Version 1.1 was last release
• Recently many new features have

been added by Josh Albert

• An official release will happen soon
• I suggest getting the latest github version
• Developers are welcome!
• Slack workspace: snowglobes.slack.com


...let me know if you want an invitation

http://phy.duke.edu/~schol/snowglobes

Interaction rates in a detector material

R = Φ σ Nt

Flux

Cross section Number of targets

∝ detector mass, 1/D2

But: fluxes, cross-sections are Eν dependent

dn dE0 = N

R 1 R 1 dEd ˆ EΦ(E)σ(E)k(E − ˆ E)T( ˆ E)V ( ˆ E − E0)

Flux

Cross section Detector response (detector simulation) Interaction products (physics)

SNOwGLoBES does this calculation for you

E’: observed energy k: observed energy for given neutrino energy T: detector efficiency V: detector resolution

flux ⊗ xscn ⊗ interaction products ⊗ detector response

Tool for predicting neutrino event rates SNOw GLoBES

neutrino flux differential spectra w/physics smearing matrix for given detector config: includes both interaction product distributions and detector response

post- smearing efficiency interaction rates, as a function of neutrino energy ‘smeared’ rates as a function of detected energy cross- sections for relevant channels

what we see in a detector

http://phy.duke.edu/~schol/snowglobes

flux ⊗ xscn ⊗ interaction products ⊗ detector response

The package includes:

• event folding code
• example fluxes and utilities

for manipulation

• standard cross sections
• standard smearing matrices,

efficiency files + for different detector configurations, + utilities for manipulating them

• example Root plotting scripts

You can easily add your own stuff, or make variants of the standard ones

SNOwGLoBES terminology

• Flux: this is really fluence,

i.e. flux integrated over time (neutrinos per cm2 in a time bin)

• Channel: an interaction channel,

with a name, e.g., ibd

• Detector material: a material for which

several interaction channels are defined (water, argon, lead, etc.)

• Detector configuration: a specific detector

corresponding to a detector material

• f a given mass, for which

smearing and efficiencies are defined (e.g. ar17kt*, halo, etc.) for each channel of the material

*a relic of old-LBNE era, will change

Inputs: these have standardized GLoBES format Flux this is really fluence, i.e. flux integrated over time (neutrinos per cm2 in a time bin)

• all 6 flavors are included, although for SN only

νe,νµ,νx; convention is νx equally distributed among the 4 muon and tau species

• some standard fluxes (livermore, gkvm)

are included,as well as a utility to produce “pinched fluxes”

• oscillation is handled at the flux stage
• (utility for MSW oscillation in SN also included)

Example:

quasi-thermal spectrum expected (“pinched” Fermi-Dirac)

hEνei < hE¯

νei < hEνxi

Cross sections

in standard GLoBES format, for all 6 flavors The channels files for a given material contain the cross section names for that material

Name/chan number/ CP/ flavor/targets per ref target

Smearing matrices: tell you the distribution of observed

energy for an input neutrino energy distribution, for a given channel and detector

A column for a given true neutrino energy is the “image” of that Eν: the distribution of observed energies

these incorporate both the distribution of interaction products and the detector resolution

(there are tools to separate these two effects)

=

smearing matrix

interacted energy dist

• bserved energy dist

Smearing matrices must be defined for each interaction channel for a given detector configuration Utilities to view and manipulate smearing matrices are in $SNOWGLOBES/smearing_code

Post-smearing efficiencies: detection efficiency after smearing

• Specified for channel and detector configuration
• Not required; 100% efficiency assumed if file absent

To compute rates in argon: ar17kt detector configuration

./supernova.pl livermore argon ar17kt

Output goes to the out subdirectory, labeled by flux, channel and configuration

• “_smeared.dat” are the observed distributions
• “.dat” are the interacted distributions
• ignore “unweighted”

You can use the example Root plotting scripts,

• r plot in any way you like

...

So let’s install:

• First install GLoBES (usually the hardest part)
• get the most recent version
• Get SNOwGLobes from github

Now run, and plot the output:

./supernova.pl livermore argon ar17kt

Next: handling time-dependent fluxes

Describe the flux by parameters vs time

• L. Huedepohl et al.,

PRL 104 251101

= νµ + ¯ νµ + ντ + ¯ ντ

Fluxes as a function

• f time

and energy

νe

¯ νe

νx

Time (s)

Energy (MeV)

= νµ + ¯ νµ + ντ + ¯ ντ