1 | |
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2 | The photo-evaporation database contains nuclear deexcitation data starting |
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3 | from a given nuclear level. Each file contains data for a given isotope, |
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4 | identified by Z and A. |
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5 | |
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6 | The database must first be downloaded from |
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7 | |
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8 | http://geant4.web.cern.ch/geant4/support/download.shtml |
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9 | |
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10 | and stored in a local directory. The environment variable |
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11 | G4LEVELGAMMADATA must then be set to point to this directory. |
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12 | |
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13 | ************************************************** |
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14 | |
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15 | Each line contains a de-excitation *step* from a given energy level to a lower |
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16 | one (which might be the ground state). Notice that if multiple de-excitation |
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17 | channels are allowed for the starting energy level, these channels will be |
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18 | described in more lines (all having the same starting level). |
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19 | |
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20 | |
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21 | Each line contains 17 columns: |
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22 | |
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23 | 1) Energy of the starting nuclear level (keV) |
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24 | As mentioned before, it is possible to have more lines describing the same |
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25 | starting level, in the case where multiple de-excitation schemes are |
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26 | allowed. |
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27 | |
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28 | 2) Energy of the transition (keV) |
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29 | This is the energy difference between the initial and the final level. |
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30 | |
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31 | 3) Transition probability (%) |
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32 | Note1: if the probability is less than minProbability = 1e-8%, it is forced |
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33 | to be 1e-8%. |
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34 | Note2: transition probabilities from a given level do not always sum up to |
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35 | 100% exactly. They are re-normalized internally. |
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36 | |
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37 | 4) Polarity |
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38 | Spin-parity variation in the transition |
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39 | [never used in real simulation] |
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40 | |
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41 | 5) Level half-life (s) |
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42 | |
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43 | 6) Angular Momentum |
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44 | Spin of the initial level |
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45 | [never used in real simulation] |
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46 | |
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47 | 7) Total internal conversion probability |
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48 | Note: the value in item (3) is the *transition* probability, so the |
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49 | actual *gamma* probability is calculated taking into account the |
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50 | probability of internal conversion. |
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51 | |
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52 | 8-17) Partial conversion probabilities for |
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53 | K-shell |
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54 | L1-3 shells |
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55 | M1-5 shells |
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56 | Outer shells (shellID = 9 is used, when applicable) |
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57 | |
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58 | Note: if the nuclear excitation energy does not match any of the known levels, |
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59 | the *nearest* level is always considered. In G4RadioactiveDecay, |
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60 | metastable states are treated correctly if the excitation energy is |
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61 | within 2.0 keV of the values in $G4RADIOACTIVEDATA. |
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62 | |
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63 | For instance: take file $G4LEVELGAMMADATA/z28.a60 (Ni-60) |
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64 | Co-60 radioactive decay populates the 1332.5080-keV level of |
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65 | Ni-60 (0.12%) or the 2505.7480-keV level of Ni-60 (99.88%). |
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66 | |
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67 | Deexcitation from the 2505.7480-keV level is described in lines |
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68 | 6-8 of $G4LEVELGAMMADATA/z28.a60 (Ni-60) |
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69 | The nucleus will release |
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70 | 1) 347 keV with 7.6e-3% probability, ending up in the 2158-keV level |
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71 | (following de-excitation hence takes place, lines 2-4 of the file) |
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72 | 2) 1173 keV with 100% probability, ending up in the 1332-keV |
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73 | excited state (following de-excitation hence takes place, line 1) |
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74 | 2) 2505 keV with 2e-6% probability ending up in the ground state. |
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75 | |
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76 | |
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