Goal

Simulate neutrino interactions changing the composition of a neutrino-driven wind.

• $\nu_e$ + n –> e + p
• $\bar{\nu}_e$ + p –> e⁺ + n

Procedure

• Calculate reaction rates given electron neutrino energy & flux, and electron anti-neutrino energy and flux
• modify XNet to include these reaction rates
• Run XNet over a typical neutrino-driven wind trajectory.

Resources

• Neutrino cross-sections for n and p (Burrows, Reddy, Thompson 2006)
• neutrino-driven wind trajectory (from Raph Hix, or arxiv.org/pdf/astro-ph/9912156.pdf, or arxiv.org/pdf/0908.1871.pdf)
• Git repository; https://github.com/srichers/NuWind.git

Adding neutrino rates to XNet

• net_preprocess.f90
  • in the desc_known list, include an entry “nu11” and “au12” for neutrino and antineutrino (no reason for the numbers - arbitrary name)
  • increase ndesc by 2 (152–>154) to account for additional entries
  • introduce new case in idesc switch statement (we called it case 153 and 154). set iec to 11 and 12 (matching the names above). Farther down, iwk1(n) is set to iec, where n is the number of the reaction.
• common.f90
  • iweak>0 means include all (including weak) interactions. iweak<0 means ONLY weak interactions
  • define formula for cross section for both neutrinos and antineutrinos in the switch statement if(iweak>0)
  • rpf1 is set to inverse partition-function stuff if inverse rate, 1 if forward rate (determined by whether a “v” is in the reaction rate database entry
  • csect1 = reaction rate = (number flux)*(cross section)

Input Parameters

Extracted input parameters from T. Fischer et al. using GSYS 2.4 (a program to extract data points from graphs) http://www.jcprg.org/gsys

Simulations

Ran simulations using xnet for different $Y_e$ values and different progenitor masses. We tried to see the effect of the presence of neutrinos and anti-neutrinos in the r-process abundance patern.