This page summarizes the SPICE commands most commonly used during routine HODACA measurements.
For detailed command descriptions, see SPICE Command Reference.
For sample alignment and UB-matrix setup, see Alignment & UB Matrix.
For longer measurement sequences, see Macros & Examples.
begin
begin
Starts a new experiment and opens the experiment-information dialog.
Enter the experiment title, user information, sample information, lattice parameters, scattering plane, and other required information.
Starting a new experiment resets some measurement settings, including the MCU value. Check the MCU setting again before starting production measurements.
drive
Moves one or more axes to absolute positions.
drive c2 -23.1
Multiple axes can be moved in one command:
drive a2 60 c2 30
Virtual axes such as h, k, l, and e can also be used when the required instrument configuration is defined.
driverel
Moves an axis relative to its current position.
driverel c2 -1
The aliases mvr and umvr can also be used.
Before making large movements, check that the requested position is safe for the installed sample environment.
cabr
Calculates the motor positions required for a specified reciprocal-lattice point without moving the instrument.
cabr 1 1 0
Use this to check the calculated A2, C2, and other motor positions before moving.
br
Moves the instrument to the specified reciprocal-lattice point using the current UB matrix.
br 1 1 0
It is good practice to use cabr first and confirm that the calculated position is mechanically accessible before using br
The virtual axis e specifies the energy transfer in meV.
For elastic scattering:
drive e 0
For example, to set an energy transfer of 0.5 meV:
drive e 0.5
When returning to E = 0, a consistent approach can be made using:
drive e -0.2
drive e 0
count
Count for a specified time:
count preset time 5
Count to a specified monitor value:
count preset monitor 100000
Count using MCU:
count preset mcu 1
preset
Sets the default counting condition used by subsequent scans or counts.
For example:
preset time 5
or
preset mcu 1
scan
Performs an absolute scan.
For example:
scan c2 -52 -50 0.1 preset time 5
This scans C2 from −52° to −50° in 0.1° steps with 5 s counting at each point.
scanrelt
Performs a relative scan around the current position with a specified counting time.
scanrelt c2 -1 1 0.1 1
This scans C2 from −1° to +1° relative to the current position in 0.1° steps with 1 s counting at each point.
The motor returns to its original position after the scan.
th2tht
Performs a coupled A2–C2 θ–2θ scan around the current position.
th2tht -2 2 0.2 1
The first three parameters specify the relative A2 range and step size. The final parameter is the counting time in seconds.
This command is commonly used when refining a Bragg reflection during sample alignment.
hold
After refining the sample tilt, rx and ry can be held so that reciprocal-space moves do not attempt to readjust them.
hold rx 1 ry 1
To release an axis:
hold rx 0
or
hold ry 0
If you are unsure which axis corresponds to the required physical tilt direction, close the neutron shutter and visually check the goniometer before moving it.
HODACA normally uses a Lake Shore 335 temperature controller for compatible sample environments.
te
Sets the temperature set point in K.
te 10
sets the temperature set point to 10 K.
ls335range
Sets the heater range:
ls335range 0
ls335range 1
ls335range 2
ls335range 3
0: Off
1: Low
2: Medium
3: High
Use the heater range appropriate for the installed sample environment.
ls335status
Displays the current Lake Shore 335 configuration and status.
ls335status
This is useful for checking the set point, heater range, heater output, PID parameters, and other controller settings.
ter
Sets a temperature and waits until the specified temperature condition is satisfied.
For example:
ter b 10 0.5 30 600
This sets the temperature to 10 K and waits until channel B remains within 10 ± 0.5 K for 30 s.
The final value is the timeout in seconds. If the timeout is reached, SPICE proceeds even if the temperature has not fully stabilized.
ter is useful in temperature-dependent macros.
When using the 4 K GM refrigerator, first start the 4 K GM compressor manually.
Then set the temperature controller according to the first planned measurement temperature.
If the sample should be cooled directly toward the base temperature, use:
te 1
ls335range 3
The set point is placed below the achievable base temperature so that the heater does not intentionally warm the sample during cool-down, while the temperature-control loop remains enabled.
If the first measurement will be performed at a higher temperature, set that temperature directly. For example, for a first measurement at 100 K:
te 100
ls335range 3
As the sample cools, the temperature controller will regulate the temperature when it approaches the set point.
The temperature set point can subsequently be changed using te as required for the measurement sequence.
For example:
te 50
Check the controller state when necessary using:
ls335status
For detailed SPICE syntax and less frequently used commands, see SPICE Command Reference.
For setting up the sample orientation and UB matrix, see Alignment & UB Matrix.
For A2–C2 maps, energy scans, temperature-dependent measurements, and longer measurement sequences, see Macros & Examples.
For sample-environment preparation, cooling times, and operating notes, see Sample Environment.