multipolarity-mixing-ratio

name	multipolarity-mixing-ratio
description	Use this skill as a reference guide for ENSDF multipolarity (M) and mixing ratio (MR) field notation. Covers E1/M1/E2/M2 designations, shorthand D/Q/O, mixed M1+E2 formatting, symmetric and asymmetric DMR uncertainties, and exact column positions 33-41 (M) and 42-49 (MR). Suitable for writing or reviewing G-record multipolarity fields.
argument-hint	["multipolarity expression or G-record line"]

ENSDF Multipolarity and Mixing Ratio Reference

ENSDF 80-column data record and field definitions, structural rules, column positions, and uncertainty notation: .github/agents/ENSDF-Agent.agent.md. Spot-check policy: .github/copilot-instructions.md.

Multipolarity Field Notation

Multipolarity Field (M Field, Columns 33-41)

ENSDF Shorthand Notation: The multipolarity field uses standard abbreviations for electromagnetic transition types.

Single Multipolarities

• D: Dipole transition (electric E1 or magnetic M1)
• Q: Quadrupole transition (electric E2 or magnetic M2)
• O: Octupole transition (electric E3 or magnetic M3)
• E1, E2, E3, ...: Electric multipole transitions (full notation)
• M1, M2, M3, ...: Magnetic multipole transitions (full notation)

Mixed Multipolarities (Combinations)

• D+Q: Mixed dipole and quadrupole (e.g., M1+E2)
• D(+Q): Predominantly dipole with small quadrupole admixture
• (D+Q): Tentative or uncertain mixed transition assignment
• Q+O: Mixed quadrupole and octupole
• M1+E2: Explicit mixed magnetic dipole and electric quadrupole
• M2+E3: Explicit mixed magnetic quadrupole and electric octupole

Critical Formatting Rules

• LEFT-JUSTIFIED in columns 33-41
• Shorthand (D, Q, O) is valid ENSDF notation — do NOT auto-replace with full notation unless specified
• Parentheses indicate uncertainty in multipolarity assignment
• Plus sign (+) indicates mixed transitions with comparable amplitudes
• Full notation (E1, M1, E2, etc.) provides explicit multipole type specification

Examples

Column:  33333333334
         3456789012
Format:  
Q                   → Pure quadrupole (shorthand)
D                   → Pure dipole (shorthand)
E2                  → Electric quadrupole (full notation)
M1+E2               → Mixed magnetic dipole + electric quadrupole
D+Q                 → Mixed dipole + quadrupole (shorthand)
(D+Q)               → Tentative mixed dipole + quadrupole
D(+Q)               → Predominantly dipole with small quadrupole component

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Multipole Mixing Ratios

Mixing Ratio Field (MR Field, Columns 42-49)

Nuclear Physics Definition: Multipole mixing ratios (δ) quantify the degree to which different angular momentum multipoles (like E1 and M2) are mixed in a gamma-ray transition. They represent the amplitude ratio between different electromagnetic transition modes.

Physical Significance

• δ = 0: Pure transition (single multipolarity, e.g., pure E2)
• δ ≠ 0: Mixed transition (multiple multipolarities contributing)
• δ(E2/M1): Ratio of electric quadrupole to magnetic dipole amplitudes
• δ(M1/E2): Ratio of magnetic dipole to electric quadrupole amplitudes
• Angular correlation: Mixing ratios determine gamma-ray angular distributions and correlations

MR Field Examples (Columns 42-49)

+1.23           → δ = +1.23
-0.45           → δ = -0.45  
>+2.1           → δ > +2.1
<-0.8           → δ < -0.8
+0.123          → δ = +0.123
-12.3           → δ = -12.3

Multiple Mixing Ratios

Mixing ratios are spin dependent. For transitions from levels with multiple possible spins, list all allowed mixing ratios in a cG comment line.

Example:

 35CL cG MR$+0.7 {I+12-2} for J=5/2; -0.40 {I+8-9} for J=9/2

Mixing Ratio Uncertainties (DMR Field, Columns 50-55)

The DMR field supports both symmetric and asymmetric uncertainties.

Symmetric Uncertainties (1-2 Digits)

• Format: Left-justified digits with trailing spaces

Asymmetric Uncertainties (+X-Y Format)

• Format: +X-Y notation left-justified in 6-character field
• Examples: +0.5-0.3, +2.1-1.8, +15-8, +0.12-0.09
• Physics context: Common when systematic effects dominate or when theoretical calculations have asymmetric confidence intervals

Special DMR Field Cases

• Limit measurements: Use GT/LT when MR field has a lower/upper limit

Critical Formatting Rules for Mixing Ratios

• Always include sign in MR field (+ or -)
• LEFT-JUSTIFY all values in both MR and DMR fields
• Asymmetric uncertainties use full 6-character DMR field
• No exponential notation — use decimal format only
• Space padding for values shorter than field width