==================
VITESS Version 2.5
==================


=====================
I  Necessary Changes  
=====================

Instruments designed with Vitess 2.4 may give no or different results due to the 
following changes (for details see chapter III):
 - GUI of the 'source' module has been changed
 - 'spacewindow(_multiple)' and 'chopper_disc' need more parameters
 - definition of the axle position of the 'chopper disc' was changed
 - sign of the angle of rotation was changed in 'sample_reflectom'



====================
II  General Features   
====================

Number of trajectories
----------------------
The limitation of the number of trajectories has been removed.

Parameter directory
-------------------
The log file is to be found in the parameter directory. Modules and
tools are more aware of this directory, so that all output of a simulation
should be found there.

Plot of result files
--------------------
From this version it is possible to plot results automaticly after the simulation 
by setting the corresponding option in the monitor and evaluate modules.

Instrument file
---------------
If the simulation is finished normally, i.e. without error, 'kill', or 'stop', a file 
called 'instrument.inf' is written to the parameter directory. It contains the end 
position of each module and the starting position of the module source in a fixed 
co-ordinate system, let's say the 'instrument hall system'. It shall be the basis of 
an instrument drawing, which will (hopefully) be delivered with the next version.

Series of simulations
---------------------
A series of simulations can now be started from the GUI (File -> GenerateSeries). 
After defining the parameters to be changed and giving their values the series can
be started and saved (for details see help file).
There are no restrictions concerning command length any more, as it was with the old 
version on the Windows platform. For those who like to continue to work with the old
version the executable gener_batch is still delivered (including correction of the 
header generation in Windows).

Colour
------
The use of colour is extended. Apart from the source, the colour can now be set by
the chopper window that the trajectory has passed. If a colour is set, the count rate of 
the existing colours (max. 3 colours) appears in the output in addition to the total 
count rate. The module 'monitor1' can display the count rate of a special colour.  
Notes: 
All settings of the colour by previous modules are forgotten, if it is set. 
Colour 0 means that it is not set by any module.

Examples of simulations
-----------------------
Some new examples of simulations were added:

    a) NRSE - resonance spin-echo instrument
    b) NSE with foils - spin-echo instrument with rotating fields
    c) resonance flipper
    d) gradient flipper
    d) two kinds of Drabkin resonator - meander and sin_distribution



=======================
III  Modules and Tools
=======================

New modules:
============

resonator_drabkin
-----------------
This module simulates a system, which is called "Drabkin resonator". This is a spin-flipper, 
which works in a narrow wavelength interval and can be used as a monochromator. Three kinds 
of distributions of the periodical magnetic field amplitude are used: permanent(meander), 
sinus and gauss distributions. Useful for TOF instruments.

flipper_gradient
----------------
This module simulates a gradient flipper, which can handle wide wavelength intervals.
It performs flipping of neutrons starting from about 2-4 Angs, depending on the flipper 
parameters. Very useful for TOF instruments .

space
-----
This module simulates a free flight path to the next module without anything in between.


New tools:
==========
Crystal Analyser Spectrometer:
-----------------------------
This tool calculates geometric details of a schematic crystal analyser spectrometer following
the theory (for details see J. M. Carpenter et al in NIMPR A483 (2002) 784-806). 
This tool can be used to obtain the input parameters for a complete VITESS simulation.
An example of such calculation can be found in FILES/CAS_DIR.

LatticeDistances
----------------
This tool generates files containing distances of lattice plains as used in the module 
'sample_powder'. (Up to now, only FCC lattices can be treated.)

DistTimePlot
------------
This tool generates a ps-file containing a distance-time-plot to check and visualize 
the designed chopper system



Improvements and changes in existing modules
============================================

source
------
1) Due to some complaints, we have put back part of changes in the source module. We promise: 
This is the last change.
In the module list, you can already choose a target station giving you a suggestion for the 
moderator file. This file contains only moderator data; (they can be changed on the moderator 
window). Simulation data (and target station data for pulsed sources) are all given on the 
main window. 
The data in the moderator description file can be seen as fixed for a special moderator on a 
source. The files containing these data are collected in <Vitess_dir>/FILES/moderators. 
(If you provide us with a moderator description file of your source, we can add it to the 
list.) The simulation data have to be set for each simulation.
HELP: We recommend to delete the first row of data and the last 2 columns of the other data 
row(s) using a normal editor, in order to restore the moderator data (rows beginning with '#' 
are only comments).
2) Calculation of absolute flux values has been corrected for flux distributions from files 
using non-equidistant wavelength or time spacing.

of the old moderator 

spacewindow  and  spacewindow_multiple
--------------------------------------

Two materials (and options) were added: outer and inner material. The shape of 
inner material is desribed by the option "window shape". Each material can be 
characterized by a file. The outer material can be chosen from the GUI list. 
This is useful for the simulations of general collimators.



chopper_disc
------------
1) The definition of the chopper position has been changed (see also help file): 
Instead of giving the vert. distance to the beamline, the z-position of the chopper
axle (in the co-ordinate system of the beam) is now required. For a chopper below the
beam, a negative value for 'vert. position' and a 'window position' of 0 deg is required;
for a chopper above the beam the 'vert. position' is positive, but a 'window position' 
of 180 deg (or -180 deg) is necessary. ('window position' is the angle relative to the 
direction of the positive z-axis, see also examples chop_10xyz.dat)
2) The option 'absorption' is renamed for the sake of clarity, i.e. 'ideal' has to be 
given instead of 'off'. The module has 2 new options: 'treat neutrons passing by' (see 
help file) and 'set colour'; they have to be set. If 'set colour' is chosen, the colour 
of the trajectory is defined by the window that the trajectory has passed. 
3) If 'desired wavelength' is given in the source module, initial phases are calculated 
(for all apertures) and written to 'instrument.inf'

sample_reflectom
----------------
Another change is the opposite sign in the reflection angle of the reflectometer sample. 
Now it fits to the rotation convention used in other modules.
Another change is that only one angle of rotation is still allowed. For several angles, 
the option 'series of simulations' (see above) must be used.

guide
-----
It is now possible to set the coatings of top and bottom planes differently. If no 
coating for the bottom is given, the top coating is used. 
The pieces of the guide may form a parabolic or elliptic shape now. As for the curved 
guide, each piece is still straight.
The loss of trajectories by waviness is corrected for all kinds of guides.

rotating_field
--------------
Module rotating_field was rewritten and improoved. It is possible now to use rotating
field with non-permanent amplitude. Also you can use internal calculator for calculation
of amplitude of rotating magnetic field for PI-flip condition. Also you can add permanent
magnetic field as additional component.



================
IV  GUI Changes
================

You may copy all parameter values of a visible module by " Edit | Copy Module Parameters "
and paste these values to another module of the same kind in the pipe with
" Edit | Paste Module Parameters ".

Tools like "Crystal Analyzer Spectrometer" and "Design Chopper System" have GUI-support 
now.

Vitess warns you before loading a new instrument or exiting, if the actual instrument
setting has not been saved.

For better plots Vitess uses the BLT enhanced Tcl/Tk Version, which is included in the 
Windows install executable (either TclTk 8.3 or 8.4.5, plus BLT 2.4z). 1-dimensionsal
plots can have 2 different modes (see " Options | Plotmode ")

Simulation can automatically be copied in a subdirectory of the parameter directory 
to avoid deleting by the following simulation (" Options | Copy results ").
