alpha-decay-q-value: Скилл расчета Q-значений для ENSDF

--- name: alpha-decay-q-value description: > Use this skill when calculating Q-alpha values from measured alpha energies and updating the Q field (cols 65-74) and DQ field (cols 75-76) in ENSDF P records. Uses exact kinematic formula Q = E_alpha * A/(A-4). Applies to single files or chains of alpha-decay datasets. --- # Alpha Decay Q-Value Calculation and P Record Update ENSDF 80-column data record and field definitions, structural rules, column positions, uncertainty notation, and spot-check policy: `.github/copilot-instructions.md`. ## Purpose Compute $Q_alpha$ from the measured alpha energy $E_alpha$ and populate the Q and DQ fields in the parent P record of each ENSDF alpha-decay dataset. ## Formula $$Q_alpha = E_alpha times frac{A_text{parent}}{A_text{parent} - 4}$$ $$delta Q_alpha = delta E_alpha times frac{A_text{parent}}{A_text{parent} - 4}$$ Round both to the nearest integer (keV precision). ## P Record Field Layout | Field | Columns (1-based) | Width | | :--- | :--- | :--- | | Q (Q-value) | 65–74 | 10 chars, left-justified | | DQ (uncertainty) | 75–76 | 2 chars, left-justified | ## Input Sources - $E_alpha$ and $delta E_alpha$: from the A record (cols 10–19, 20–21) **or** from the `QP$From E|a=` comment line. - $A_text{parent}$: mass number of the parent nuclide (from NUCID in the P record). ## Workflow ### Step 1: Read $E_alpha$ and $delta E_alpha$ From the `cP QP$` comment line (preferred, as it identifies the g.s.-to-g.s. transition): ``` 219NP cP QP$From E|a=9015 keV {I16} g.s. to g.s. transition ... ``` Extract 9015 and 16. Or directly from the daughter A record (cols 10–19 and 20–21). ### Step 2: Identify $A_text{parent}$ Read cols 1–3 of the P record NUCID. For `219NP P ...`, $A = 219$. ### Step 3: Compute and Round ```python Q = round(Ea * A / (A - 4)) DQ = round(DEa * A / (A - 4)) ``` ### Step 4: Write into P Record - Cols 65–74 (index 64–73): `str(Q).ljust(10)` - Cols 75–76 (index 74–75): `str(DQ).ljust(2)` - Verify total line length = 80 chars. ```python new_line = s[:64] + str(Q).ljust(10) + str(DQ).ljust(2) + s[76:80] + 'n' ``` ### Step 5: Validate Run ruler on the modified P record line: ``` python .github/scripts/ensdf_1line_ruler.py --line "modified line here" ``` ## Example | Parent | $A$ | $E_alpha$ (keV) | $delta E_alpha$ | $Q_alpha$ | $delta Q$ | | :----- | :-: | :--------------: | :---------------: | :--------: | :--------: | | 219NP | 219 | 9015 | 16 | **9183** | **16** | | 215PA | 215 | 8087 | 12 | **8240** | **12** | | 211AC | 211 | 7451 | 9 | **7595** | **9** | | 207FR | 207 | 6762 | 8 | **6895** | **8** | ## Common Errors | Error | Cause | Fix | | :---- | :---- | :-- | | Q copied from $E_alpha$ directly | Forgot kinematic factor | Always apply $A/(A-4)$ | | DQ wrong | Used wrong $A$ or forgot to round | Recompute with correct $A$ | | Line length ≠ 80 | `s[76:80]` truncated | Ensure source line is `.ljust(80)` before slicing | ## Notes - For an alpha-decay chain, process each file independently; each file has its own $A_text{parent}$. - The P record Q field represents $Q_alpha$ for the **parent** decay (g.s. to g.s.). - Do **not** confuse with the daughter L-record energy (always 0 for g.s.).