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Disk chopper time-of-flight spectrometer IN5

IN5 is a high precision direct geometry Time-of-flight (ToF) spectrometer. It is used to study low-energy transfer processes as a function of momentum transfer (e.g. quasi-elastic scattering in solids, liquids, molecular crystals and inelastic scattering, etc ). Typically this instrument is used for measurements in the small energy (10 µeV - 100 meV) and momentum transfer region with values of about 1 % for the energy resolution .

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Basic data reduction

The basic data treatment for obtaining the standard output S(2θ, ToF) require a few steps that are made within LAMP through a bunch of routines grouped in a batch file called in5_reduce.prox.  At the moment these routines are under development and it is not expected to build a pure black box for the basic transformations before the routines have been improved and fully tested. All necessary routines including the .prox files are directly accessible by LAMP. Thus, there is nothing to copy to the user directory unless a modification is necessary in the in5_reduce.prox. In that case, routines and prox files are accessible through the LAMP menu: "Edit" -> "users batch files, MACROS".


The steps for going from the raw 3D data to the standard S(2θ, ToF) view is as follow within LAMP:

1) set the variable "b" (as for begin) to the first run number and "e'' (as for end) to the last run number to add in the spectrum. If only one run, "e" should be equal to "b". 

2) Strike "@in5_reduce" (without the quotation marks) in LAMP (see the content of the file @in5_reduce).

The steps above can be put inside a batch .prox file of course (see the picture).


For using it outside the ILL you need some routines specific to IN5 to be inserted in LAMP. If you have the IDL software and run LAMP from the sources, add the content of  reduce_source.tar.gz in one of the subdirectories accessible by LAMP (strike print, !path in IDL to know them). If your are running the runtime version of LAMP, put the content of  reduce.tar.gz (compiled routines) in the  ...Freelamp/lamp/lamp_mac/ directory and restart LAMP.

WARNING: Since recently (now: 2009-11-12) some problems may occurs with the data reading in one subroutine (read_hdf) that is independant from the IN5 instrument. We have no solution at the moment unless you can compile the routine in the sources above.

 The resulting S(2θ, ToF) is in the W4 workspace from the in5_reduce prox batch. The reduced S(2θ, ToF) data are also recorded in hdf format (hierarchical data format) a file which name is: run_<first number>_<last number>_ToF.hdf.  For further data treatment concerning the standard S(2θ, ToF) it is only necessary to load (transparently in LAMP) the saved processed data.


Bugs reports and questions to: J. ollivier (ollivier(at)ill.fr)

Standard data reduction for S(2θ,ToF)

The standard instrumental corrections (background substraction, vanadium normalisation, ...) are made starting from the saved .hdf files coming out from the above steps. It is theoretically possible to reuse the INX program but there lack a routine transforming the hdf data into the former time-of-flight ASCII raw data format. In order to use your own set of routines the easiest is to import the hdf data in your routines thanks to the numerous library able to import / export the well known hdf format.

All the operations made previously within INX (or equivalent software) can be made within LAMP. A "prox" template is accessible from LAMP: standard1.prox through the "Users batch file, MACROS" menu. The different steps of a standard data reduction are explained in the file. All the steps are not compulsory depending on the type of data reduction expected (S(2θ,ω) or S(Q,ω),... ). Comment or remove the unwanted lines of the prox in your working directory.

While using the LAMP runtime version, before playing the standard1.prox batch file below, you will need to install the compiled routines ".sav" in the LAMP runtime directory (see next page).  Click on standard1.prox to have a look at the standard procedure. 

Output data format might be chosen between the conservative INX (CROSSX) format for those who have their fitting routines reading this format or the HDF format that keep the parameters set of the experiment in each file. This format might be also lighter in disk space.


Basic data reduction for single crystal

For a single crystal experiment all the pixels of the detectors are processed individually or after grouping. There is also less transformation steps, althugh more data to process. A file named singleCrystal.prox is in the same directory than above and can be stored on the working directory if changes are needed though the LAMP menu.


singleCrystal.prox


Data are stored in the SPE text format to be read and analysed with "mSlice" or the Horace suite from ISIS. They can be stored in HDF format as well by changing the storage routine. The miscellaneous files PHX and PAR files are also created while storing the data. They can then be directly processed using the above mentioned routines provided you find a Windows 32bits with Matlab intalled with 4Gb of RAM.