This shows you the differences between two versions of the page.
Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
panda:measure:index [2017/05/15 07:35] – ↷ Page moved and renamed from panda:measurement to panda:measure:index pcermak | panda:measure:index [2020/10/05 17:13] (current) – Astrid Schneidewind | ||
---|---|---|---|
Line 1: | Line 1: | ||
====== Measurement tips ====== | ====== Measurement tips ====== | ||
+ | |||
+ | <WRAP half column round box> | ||
+ | ===== Typical inelastic (TAS) neutron experiment | ||
+ | {{ : | ||
+ | |||
+ | Before coming to the instrument: | ||
+ | |||
+ | Know your system' | ||
+ | Decide about the sample orientation - you get only one plane | ||
+ | |||
+ | Create hkl-intensity-list (reflection list). --> info about forbidden reflections and the (relative) intensities of the allowed. - Have it available for starting the experiment. | ||
+ | |||
+ | Mark the crystal direction on the sample holder | ||
+ | |||
+ | 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. | ||
+ | |||
+ | Mark the crystal direction outside on the cryostat | ||
+ | |||
+ | 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. | ||
+ | |||
+ | Start experiment. Experiment name, sample name, give sample metadata to system | ||
+ | |||
+ | Align the sample | ||
+ | |||
+ | * 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!!!! | ||
+ | |||
+ | </ | ||
+ | |||
+ | |||
+ | |||
+ | <WRAP half column round box> | ||
===== Background reduction ===== | ===== Background reduction ===== | ||
Line 6: | Line 61: | ||
Background is a very important issue for PANDA. There are some (REAL) examples of how bad configuration can influence the measurement: | Background is a very important issue for PANDA. There are some (REAL) examples of how bad configuration can influence the measurement: | ||
- | * [[panda:measurement: | + | * [[panda:measure: |
- | | + | |
+ | </ |