panda:measure:index
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| panda:measure:index [2020/07/09 09:24] – ↷ Links adapted because of a move operation Michal Stekiel | panda:measure:index [2020/10/05 17:13] (current) – Astrid Schneidewind | ||
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| ====== Measurement tips ====== | ====== Measurement tips ====== | ||
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| + | <WRAP half column round box> | ||
| + | ===== Typical inelastic (TAS) neutron experiment | ||
| + | {{ : | ||
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| + | Before coming to the instrument: | ||
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| + | Know your system' | ||
| + | Decide about the sample orientation - you get only one plane | ||
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| + | Create hkl-intensity-list (reflection list). --> info about forbidden reflections and the (relative) intensities of the allowed. - Have it available for starting the experiment. | ||
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| + | Mark the crystal direction on the sample holder | ||
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| + | Mount the sample properly. Think about covering the glue or holder and about either fixing the sample by Al wire or mounting an Al foil bag around. | ||
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| + | Mark the crystal direction outside on the cryostat | ||
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| + | For magnets, sample mounting needs to be better than within 1°. Depending on the instrument, care that one crystal direction is parallel to the goniometer axis. | ||
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| + | Start experiment. Experiment name, sample name, give sample metadata to system | ||
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| + | Align the sample | ||
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| + | * move instrument to elastic position | ||
| + | * calculate (hkl) of a strong allowed refelction in your scattering plane for your kf | ||
| + | * if there is no allowed reflection within the available q-range, think about removing the filter and orient at | ||
| + | * move stt/a4 to scattering angle | ||
| + | * rotate sample for 181° minimum (sometimes SE will hinder you, then take what you get) | ||
| + | * you should find at least one reflection, and the angles between refelctions should represent the symmetry of the crystal | ||
| + | * if there are more reflections than expected or the angles are wrong: filter forgotten? more than one grain? - think and decide | ||
| + | * if ok - move sth/a3 to maximum of the reflection. Take the one better suited for SE/other constraints | ||
| + | * go to maximum of the peak, define sth/a3 for the reflection [panda: setalign((h, | ||
| + | * gonio-scan in the related direction, go to max. | ||
| + | * check height | ||
| + | * repeat gonio-scan, until there is no relevant change | ||
| + | * check the lattice parameter. Care that horizontal focus is flat for this scan. | ||
| + | * adjust lattice parameter | ||
| + | * check gonio, height, lattice parameter iteratively up to no relevant changes occur. care about foci | ||
| + | * after last lattice parameter scan, define sth/a3 | ||
| + | * claculate orthogonal reflection | ||
| + | * go there, you should find it immediately | ||
| + | * gonio-scan, lattice parameter iteratively (remember foci. height should be ok) | ||
| + | * adjust lattice patametr, fix gonios | ||
| + | * in case sth/a3 does not fit perfectly for both reflections, | ||
| + | * check lattice parameters at the temperature you want to measure | ||
| + | * start first inelastic scans | ||
| + | |||
| + | Good luck!!!! | ||
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| + | </ | ||
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| + | <WRAP half column round box> | ||
| ===== Background reduction ===== | ===== Background reduction ===== | ||
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| * [[panda: | * [[panda: | ||
| - | * | + | |
| + | </ | ||
panda/measure/index.1594286690.txt.gz · Last modified: 2020/07/09 09:24 by Michal Stekiel
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