AIDA
GELINA
BRIKEN
nToF
CRIB
ISOLDE
CIRCE
nTOFCapture
DESPEC
DTAS
EDI_PSA
179Ta
CARME
StellarModelling
DCF
K40
CRIB
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Thu Apr 17 04:41:38 2025
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> Attachment 1 shows a comparison of the zero-degree telescope from the decay measurement with the 26gAl beam produced today (left side) and a GEANT4 simulation by Shimizu kun > some months ago. > > I discovered two reasons that July 2016's beta spectrum did not match the simuation: > 1) The threshold was too high, so we should try to decrease it during another test soon > 2) There was a strange bug in the code that also affected the spectral shape. > > Now the comparison of the beta spectrum between our measurement today and the GEANT4 simulation is excellent. (There are some differences in the setup, so that may account for > some of the small variations). > > My calculation of the isomeric purity output the following results: > > root [0] .x macros/purity.C > Run number: 46 > Solid angle: 0.0386799 > Betas: 3.42938e+07 > Purity (PPACa): 0.862612 > Purity (PPACb): 0.906841 > Isomeric purity (PPACa): 0.281095 > Isomeric purity (PPACb): 0.276141 > > (This differs from the online logbook, as I mistakenly used the PSD solid angle instead of the first SSD layer.) > > Keep in mind that the lowest-energy tail of the beta-spectrum in the experimental data are absent, and so the actual isomeric purity is slightly higher than above (but it seems > negligible if I take the 25 keV/bin setting, assumed from 0~200 keV misses around 500 counts per bin) > > Still, the beam seems to be around 70% ground state. However, keep in mind that our isomeric purity from the test run was somewhere around 42% so the difference is only 10% > which may be small, and so we should make a stronger effort to make the higher purity isomeric beam, maybe tomorrow.
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ELOG V3.1.4-unknown