unzhakov
ed3fd5dc9d
- Add Z (nuclear charge) and A (mass number) parameters to RadiativeCorrection - Implement O(Z*alpha^2) finite nuclear size correction per Sirlin 1987: - Energy-dependent part: ln(m_p) - (5/12)*ln(2W) + 43/18 - Nuclear-structure-dependent part: Delta_F(Z,A) from modified Gaussian model - Add small-beta Taylor expansion for numerical stability at threshold (beta < 1e-6) - Extract _safe_beta() and _safe_tanh_inv_beta_over_beta() helper methods - Remove unused log_wright_bessel import - Add 14 new tests: Z-dependence, numerical stability, A parameter coverage - Update docs/06-radiative-corrections.md with new API usage examples All 70 tests pass. 14 new tests in 3 new test classes.
title, date, tags, status
| title | date | tags | status | |
|---|---|---|---|---|
| Beta Spectrum Wiki | 2026-04-26 |
|
active |
Beta Spectrum Calculator — Knowledge Base
This Obsidian vault serves as the scientific reference and development workspace for the beta-spectrum calculator project (beta_shape_pnpi).
Purpose
Organize the physics theory behind allowed beta decay spectrum calculations into structured, interconnected notes that directly inform the implementation of correction components in the codebase.
Source Material
| Reference | Type | Location |
|---|---|---|
| Hayen et al., RevModPhys 90, 015008 (2017) | Review article | pdf_source/Hayen2017.pdf / Hayen2017_summary |
Notes Structure
All notes are flat in this directory, linked via wikilinks.
Core Theory
- 00-beta-spectrum-overview — Master equation and overview of all corrections
- 02-phase-space — Baseline spectral shape
pW(W_0-W)^2
Correction Components (mapped to calculator modules)
| # | Note | Calculator Module | Status |
|---|---|---|---|
| 1 | 01-fermi-function | components/fermi.py |
✓ implemented |
| 2 | 03-finite-size | components/finite_size.py |
✓ implemented |
| 3 | 04-screening-correction | components/screening.py |
✓ implemented |
| 4 | 05-exchange-correction | components/exchange.py |
✓ implemented |
| 5 | 06-radiative-corrections | components/radiative.py |
✓ implemented |
| 6 | 07-recoil-effects | components/recoil.py |
✗ not yet implemented |
Nuclear Structure & Atomic Effects
- 10-nuclear-structure — Shape factors, form factors, impulse approximation
- 11-isospin-breakdown — Shake-off/shake-up processes, endpoint shift
- 12-atomic-overlap — Bahcall correction, bound-state β decay
- 13-chemical-effects — Molecular environment influence on spectrum
References
- refs/hayen2017 — Metadata and key equations from Hayen et al. (2017)
Calculator Architecture
SpectrumComponent (ABC, base.py)
├── PhaseSpace → phase_space.py
├── FermiFunction → fermi.py
├── FiniteSizeL0 → finite_size.py
├── ChargeDistributionU → finite_size.py
├── ScreeningCorrection → screening.py
├── ExchangeCorrection → exchange.py
└── RadiativeCorrection → radiative.py
BetaSpectrum (spectrum.py) — multiplicative composition + from_config()
BetaSpectrumAnalyzer (spectrum.py) — plotting, CSV export
Key Variables and Units
W— total electron energy in units ofm_e c^2(natural units,m_e = 1)TorE_{\text{kin}}— kinetic energy (keV or MeV)W_0— endpoint total energyZ_{\text{parent}},Z_{\text{daughter}}— atomic numbers\alpha \approx 1/137.036— fine structure constant\gamma = \sqrt{1 - (\alpha Z)^2}
Conversion: W = 1 + T / m_e c^2, with m_e c^2 = 510.998950 keV.