Instruction sheet 554 83 page 2/4
3 Zero position of the measuring system
Warning: Each time the zero position of the measuring system
is changed the old values of the zero position are overwritten in
the microprocessor memory by the new values
The zero position of the goniometer measuring system is deter-
mined by arm movement toward two light barriers with subse-
quent step correction. The correction values with reference to
the position of the light barriers are stored in the X-ray appara-
tus.
You can adjust the zero position of the measuring system most
precisely using the experiment “Bragg reflection”; the adjust-
ment is then with reference to the lattice planes of the
monocrystal.
Additionally required:
1 End-window counter for a, b, γ radiation
and x-rays 559 01
1 NaCl crystal for Bragg reflection 554 78
(in scope of supply of 554 811)
- Press the ZERO key to return the target and sensor arms to
the current zero position.
- Mount the NaCl crystal and the end-window counter (see
below).
- In coupled scanning mode, set the target to about 7.2° using
the ADJUST knob.
- Set the tube high voltage U= 35.0 kV and emission current
I= 1.00 mA and switch on the tube high voltage with
HV ON/OFF.
- Switch between sensor and target scanning modes and
locate the maximum counting rate for the first reflection
maximum of the NaCl monocrystal under manual control .
- In coupled scanning mode, move the target back by 7.2°
(even if this takes you into the negative range!).
- Save the positions of the target and the sensor as the “zero
position of the measuring system” by pressing TARGET,
COUPLED and β LIMITS simultaneously.
- To verify your adjustments, assume the angle 7.2° in
coupled scanning mode and check the maximum counting
rate.
4 Mounting and demounting
Mounting:
- Mount the target and sensor holders, if this has not already
been done.
- Lay the ribbon cable of the X-ray apparatus out flat and to
the right behind the bottom guide rod in the experiment
chamber.
- Screw off the knurled screws of the bottom guide groove.
- Set the top guide groove over the top guide rod.
- Pivot the bottom section of the goniometer onto the bottom
guide rail of the X-ray apparatus, raise the goniometer and
place it in the assembly so that the bottom guide rod slides
into the bottom guide groove of the goniometer.
- Slide the goniometer in the experiment chamber to the left
and plug the ribbon cable into the connector of the goniome-
ter (check to make sure that the polarity-reversal protectors
line up).
- Slide the goniometer to the desired distance from the colli-
mator, insert the knurled screws of the bottom guide slot and
tighten them.
- Mount the sensor.
Demounting:
- Remove the sensor from its seat.
- Screw off the knurled screws of the bottom guide groove of
the goniometer.
- Slide the goniometer in the experiment chamber to the left
and unplug the ribbon cable from the connector on the go-
niometer.
- Manually steer the sensor arm of the goniometer to the 0°
position.
- Lift the goniometer until it touches the top guide rod, lift the
bottom section of the goniometer forward and lower it until
the upper section of the goniometer can also be lifted for-
ward.
