There are 2 options:
A) ComputeChopperPhases
The phase of a chopper is calculated (cf. chapter 'direction of rotation...').
The length of the pulse is taken into account. The phase is chosen in a way
that the center of the pulse reaches the center of the chopper (at the given
length). The aperture of the chopper is used to give additional information
(about the wavelength range that can pass the chopper).
B) DesignChopperSystem
For a set of choppers, the apertures must fit to each other as well as
the phasing (cf. chapter 'pulse length....'). This application helps to
design the chopper system and to get information about the usable wavelength
range at the detector (cf. chapter 'evaluation time.....').
In both cases you can choose the average (option 'a') or the minimal (option 'm') wavelength that can pass. Some of the input or output data may need an explanation:
Parameter Unit |
Phase calculation |
Chopper system |
Description |
Range or Values |
Command Option |
repetition rate of pulses [1/s] |
X |
frequency of pulses generated by the source |
> 0 |
-R |
|
rounds / min. [1/min] |
X |
X |
rotational speed of the choppers; (different speeds
in one chopper system cannot be treated by this tool) > 0: chopper phase approaches + infinity with time; => initial phase < 0 < 0: chopper phase approaches - infinity with time; => initial phase > 0 |
> 0 or < 0 |
-s |
distance source - detector [m] |
X |
> 0 |
-D |
||
pulse length [ms] |
X |
X |
length of the neutron pulse |
>=0 |
-p |
center of pulse / delay [ms] |
X |
X |
average starting time of the neutrons pulsed source: half of pulse length continuous source: zero or half of pulse or anything else, depending on zero time |
no restriction |
-d |
max. pulse length [ms] |
X |
pulsed source: time at which intensity of pulse is
practically zero continuous source: usually = pulse length |
>= pulse length |
-m |
|
aperture (WB) chopper [deg] |
X |
X |
for phase calculation, this is the aperture
of the only chopper under consideration for the chopper-system design, this is the aperture of the wavelength band chopper |
> 0 |
-a |
distance source - (WB) chopper [m] |
X |
X |
distance to the chopper defined in the previous row |
>0 and < dist. detec. |
-C |
beam diameter at WB chopper [cm] |
X |
the beam diameter influences the half shadow time
and is therefore necessary to calculate the usable wavelength range |
> 0 |
-c |
|
distance: beam - chopper axle [cm] |
X |
(as the beam diameter), the distance beam - chopper-axle
influences the half shadow time and is therefore necessary to calculate the
usable wavelength range |
> beam diameter |
-A |
|
Distance source - FO chopper [m] |
X |
distance to the frame overlap chopper, whose aperture
and phase shall be determined |
> 0 and < dist. detec. |
-F |
|
beam diameter at FO chopper [cm] |
X |
the beam diameter determines the opening and closing
and is therefore necessary to calculate the aperture of the frame overlap
chopper |
> 0 |
-f |
|
wavelength [Ang] |
X |
X |
minimal or average wavelength that shall pass the
chopper (system) - s.a. next row |
> 0 |
-W |
wavelength range determined by |
X |
X |
the wavelength is: a: the average wavelength m: the minimal wavelength of the wavelength band that passes the chopper (system) |
> 0 |
-w |
FO chopper |
X |
the frame overlap chopper apertures are chosen in
a way that they h: do not increase the half shadow time n: do not stop any neutron of the right wavelength range that is able to pass the wavelength band chopper |
h or n |
-k |
Last modified: Tuesday, 03-Jul-2007 16:14:09 CEST