MACH3

• Introduction
• Safety instructions Read these before using the equipment
• Specifications
• Installation
• Pre-installation requirements
• Operation
• Maintenance
• Troubleshooting
• Manufacturer and Service

Introduction
 

The MACH3 system consists of a four circle goniometer (Omega, Kappa, Phi to position the crystal and Theta to position the detector) and an X-ray source. The detector measures X-rays diffracted from a crystal.

X-rays can be generated by a sealed tube which is part of the goniometer and a HV generator or by a stand alone rotating anode generator. The X-ray optics consists of a ß filter or a monochromator to suppress the ß- and brehms radiation and a collimator to get a small beam. Safety switches close the shutter or switch off the high voltage in unsafe conditions. In case of a rotating anode generator the shutter and some safeties are handled by the generator. The optics at the detector side consists of a collimator, replaceable slits, a dial unit with computer selectable slits and an attenuator to attenuate high intensities.

The axes are decoded by precision optical encoders and are driven by DC motors, that permit accurate, fast and smooth positioning with low power consumption. The goniometer is driven by an electronic interface, which has a processor, drivers and detector circuit. The system is run by software through the main program on the computer. A selected number of functions, which are needed in the vicinity of the goniometer, can be executed by a pocket terminal. The goniometer is surrounded by a radiation enclosure, which prevents scattering of radiation into the room.

• X-ray
• Beryllium

X-ray safety

The equipment generates open X-rays, which can cause to humans hazards when safety rules are not followed:

• The equipment must be operated under the responsibility of an X-ray safety officer, as stated by local regulations.
• The equipment must be operated, serviced and maintained by qualified personnel who are trained with the hazards of, and precaution against X-ray exposure.
• The equipment contains safety circuits which should not be overridden, other than supplied: the enclosure key and beamstop override vane. These overrides may only be used for service and maintenance, i.e. X-ray alignment.
• The enclosure key and beamstop override vane should not be kept with the instrument but under the custody of the X-ray safety officer. This also applies to the X-ray- or shutter safety keys of the X-ray generator in case the X-ray port is not used or X-ray is not allowed to be used.
• When using the beamstop override vane (for alignment only) the system must not be left unattended. Theta always at 0°, safety door closed, low kV/mA setting and a second lead beamstop.
• Safety circuits must be tested by service personnel or the safety officer at least every 12 months, as described in this manual
• The collimator must always be installed.

The detector and X-ray tube contain windows of beryllium. In normal use these area's cannot be reached, but during maintenance, care must be taken not to touch the window. When by accident the Beryllium is touched, wash with soap and water.

Fumes and dust from beryllium metal can be hazardous if inhaled. During use, corrosion of the beryllium window may occur, but it should not be cut, machined or otherwise removed. Tube and detector disposal must comply with the national and local regulations governing beryllium.
 
 

 

Goniometer

Anti-collision

• Automatic anti-collision software, also when using the pocket terminal..
• Axis maximum position switches. Turning back is possible.
• Collision switches on both collimator holders.

X-ray optics

 

Detector

Goniometer heads
 

Height	49.0 mm
Distance ring	14.96 mm
ECON head	X, Y: ±1.5 mm Z: 8 mm
XYZ head (option)	X, Y: ±2.5 mm Z: 8 mm
Eucentric head (option)	X, Y: ±2.5 mm Z: 3 mm angle: ±15°

 

Safety interlocks

• The collimator is not in the right position.
• The monochromator or X-ray port is not in the right position.
• The beamstop is not mounted.
• The shutter-open lamps are defect.
• The radiation enclosure is not closed.
• When using a rotating anode: the goniometer is not properly placed in front of the X-ray port.

• The shutter does not close.
• The high voltage cable is not connected to the X-ray tube (indicated by a link, attached to the cable and connected to the tube holder).
• The X-ray on lamp is defect.

The system is supplied with two overrides, which are only allowed to be used during technical maintenance (see safety rules).

• A key switch overrides the radiation enclosure safety. This state is signalled by the flashing Open-beam lamp. When the lamp is defect the override is cancelled.
• Beamstop override vane. There are no extra warnings. See X-ray safety.

With a X-ray generator all safeties are handled by the generator, except the shutter safeties: collimator and beam stop.

Safety signals

• Shutter-open lamp: illuminated when the shutter is opened or is not fully closed.
• Shutter-closed lamp (only with sealed tube): illuminated when the shutter is fully closed.
• Open-beam lamp: flashes when the radiation enclosure safety is overridden.
• X-ray lamp: illuminated when X-rays are generated.

Safety with power off

Safety demands that circuits are automatically in a safe position when they are out of order. So during power off, the goniometer Interface and the X-ray high voltage are switched off by the safeties.

Connections

 

Environmental, according to IEC 1010

 

General

Position

• The equipment must be installed in a normal, clean and temperature regulated environment and not in direct sunlight.

• The power must be connected by a detachable supply cord which is approved by national authorities.
• The power voltage is factory installed (see identification label on the Interface) and can only be changed by a service engineer.

The Interface is mounted in the cabinet or placed on the table top. The Interface must not be placed within 50 cm of the X-ray tube, to prevent electrical problems due to spilt cooling water. Ventilation holes must not be covered and no insulating or heavy object must be placed on the equipment.

Safety ground

• The equipment must be connected to the installation safety ground, e.g. through a appropriate power cable.
• The next safety ground must be checked: from the HV-generator to the X-ray tube.

Goniometer

Goniometer Interface

• Start-up
• Pocket terminal

Start-up procedure

• Start up the computer program and wait till it notice: 'Connection is made to CAD4 process'.
• Switch on the power of the Interface (or reset with the button on the front of the interface). The goniometer will slowly search for the zero reference with an anti-collision routine.
• The pocket terminal shows: 'Connecting to host computer'
• After connection the pocket terminal shows shortly all axis positions zero and then 'Zeroing procedure ongoing'
• After finding the zero reference the Goniometer will position on zero. The pocket terminal will give the position off all axis and the program proceeds. The system is ready for use.

	F1 - F4	Function or submenu
	^, v	Scroll through a setting
	*	Specials
	Shutter	Only active in Detector menu
	<, >	Position axis
	STOP	Stops all motors and closes the shutter.

character * denotes : blank = motor stop, R = motor Running
 

Submenu Axes control
Theta +###.###	Position with < and >
Speed #	Speed with ^ and v, blank: variable, from slow to fast  9  2000 °/min  6  200 °/min  3  20 °/min  8 1000 °/min  5 100 °/min  2 10 °/min  7 500 °/min  4 50 °/min  1 5 °/min

 
 

View positions
View 0	Positions to align the crystal	View 0, 1 : Position in front of the goniometer View 2, 3 : Position at the side of the goniometer The choice between 0, 1 or 2, 3 is made in the host program in the goniometer constants
View 1
Phi +90	Rotates Phi 90°. Phi also rotates with < and >
Zero	All axes 0°

 
 

Detector
###### cnt/s	Intensity, measured by the detector
Smooth ## s	Average time: choose with ^ and v, default 1
Dial aper #.# mm	Dial: shows slits or aperture.
Attenuator OFF	Attenuator on/off with F4.

 
 

Specials : *
Omega +90 degr	Rotate Omega +90°
Omega -90 degr	Rotate Omega -90°
Release motors	Power off motors
Park	Position for quick zero-find after power off (will also be executed automatic during exit of the program).

 
 

Other messages
Connecting to host computer	Tries to connect to the host program during start-up
Zeroing procedure ongoing	Goniometer is running slowly to zero to determine the zero reference position during start-up.
< Theta >	Collision. See chapter Trouble shooting.

• Cleaning
• Tools
• Safety test
• X-ray optics alignment with a sealed tube (FR590)
• Effic: intensity of the primary beam
• Reset
• Detector HV adjustment
• Replaceable parts
• Ceramic tubes
• Accessories box
• Changes:
• Programmable IC for safety (febr. 2002)

For cleaning use a damp cloth, moistened with water or isopropyl alcohol. No cleaning agent may enter the goniometer.

• Absorber: Zirconium (for Mo) or Nickel (for Cu) filter, placed on the collimator to attenuate the intensity of the primary beam to a measurable and save level. It is only allowed to used with low kV/mA settings. Specification:
• Mo: 7 foils of 0.108 mm Zr, attenuation approx. 2400x
• Cu: 9 foils of 0.02 mm Ni, attenuation approx. 1900x
• Test crystal: ammonium bitartrate.
• Dial gauge for alignment of the X-ray tube.

Shutter safety, with the FR590 or FR591.

1. Switch off the X-ray high voltage
2. Open the shutter. Check both shutter-open lamps.
3. Check if the shutter will not open after activating the next unsafe conditions. The shutter must remain closed after reestablishment of the safety (except the shutter lamps):
• Collimator loose.
• Beamstop removed.
• Radiation enclosure open.
• Shutter-open lamps removed.
• Radiation enclosure safety override with the key-switch, Beam-open lamp removed and enclosure open.
4. Check the flashing Open-beam lamp when the radiation enclosure safety is override by the key-switch.

1. Switch on the high voltage to minimum: 20 kV 5 mA
2. Check the X-ray on lamps.
3. Check if the high voltage falls off when:
• X-ray on lamps removed.
• Link of the HV-connector removed.
• Shutter is manually opened by hand: take care not to come in the vicinity of the primary beam!

1. Switch on the high voltage on minimum: 20 kV 5 mA.
2. Check if the high voltage falls off when:
• Shutter is manually opened by hand: take care not to come in the vicinity of the primary beam!
3. See safety tests in FR591 service manual.

Safety precautions

• Don't let other persons come in the neighbourhood of the system.
• Don't leave the system unattended, before reestablishment of the safety.
• Don't come in the primary beam, although for security reasons it is attenuated to a weak and safe intensity.

Measurement set-up

1. Place the 1-ring collimator.
2. Place the absorber on the collimator (take care: Mo and Cu use different absorbers).
3. Position on Zero, aperture on open hole, no beta filter.
4. Remove the beamstop and place the safety switch override. take care, the primary beam is measured, be sure Theta is always 0º or use a second beamstop (X-ray shield) behind the goniometer (the PVC windows are not sufficient to stop the primary beam), see X-ray safety instructions.
5. X-ray generator:
• Mo: 30 kV, 10 mA
• Cu: 20 kV, 10 mA
6. For measuring the intensity use the pocket terminal : detector.

Adjustment

1. Adjust Tube 2Theta to 0°.
2. Dismount the monochromator and mount the X-ray port (two Allen screws {2.5 mm} at the bottom, which can be reached by two holes {not the middle one} under the black monochromator holder). . During replacement the power of the X-ray generator must be off.
3. Adjust tube 2Theta = 0° , and take-off = 3.0° (for fine focus 0.4 x 8 mm, for normal 1 x 10 mm focus : 6.0°).
4. Adjust on approx. maximum intensity with tube vertical (Allen 4 mm) and tube horizontal (Allen 3 mm) adjustment.
5. Position slit horizontal and adjust on maximum intensity with tube vertical adjustment.
6. Position slit vertical and adjust on maximum intensity with tube horizontal adjustment.
7. If needed repeat both and lock the tube vertical adjustment (Allen 5 mm).
8. Remove the X-ray port. Switch off the power of the X-ray generator during replacement.
9. Mount the monochromator and switch on the power of the X-ray generator
10. Adjust Tube 2Theta (Mo: 12.2°, Cu: 26.6°) and the Monochromator 2Theta on the anode target material used.
11. Position on slit horizontal and adjust on maximum intensity, first with monochromator 2Theta, then tube 2Theta and monochromator height.
12. Position on slit vertical and adjust on maximum intensity with tube horizontal adjustment.
13. Repeat both several times. Lock the monochromator height and tube 2Theta.
14. Mount the test crystal (Ammonium bitartrate), place the beamstop and remove the absorber, use the 2-ring collimator, set X-ray generator: 50 kV, 20 mA (Mo and Cu).
15. Input top reflexes, or search for reflections, if the matrix is unknown.
16. Run program Align and adjust till the output is <0.01 (mm). This adjustment will lower the intensity somewhat :
 

TubeHo : adjust with tube horizontal adjustment with the dial gauge against the tube head : Turning clockwise changes TubeH in positive direction.

• Mondeg :
• adjust with monochromator-Theta adjustment: Turning upwards changes Mondeg in positive direction (Mondeg = TubeVe/4). If this adjustment decreases the intensity too much then first:
• adjust monochromator height: Turning clockwise changes Mondeg in negative direction.
• Deterr :
• EXPRESS:
• Position Theta = -deterr / 8 (approx.)
• In Specials, Goniometer constants, Motor feedback, do: Theta abs. zero
• PC DOS/Linux :
• KP, n 0 0 0 (n = -detererr / 8 (approx.))
• GONCON, CASPAR, P, EN
• TA, 0, TZ, 0, Q, Q, S, Q
• Repeat Align
17. Lock monochromator 2theta.
18. Check the intensity with the Effic measurement

Adjustment points

EFFIC: intensity of the primary beam

The effic measurement is a relative measurement of the intensity of the primary beam, which measures the total efficiency of the X-ray: tube and optics. When the value is too low it is mostly caused by the tube (degradation) or the X-ray alignment. The measurement is done during installation of the system and later measurements can be compared with this value. Take into account that because of tolerance in collimator and absorber (material thickness) the values cannot be accurately compared with other systems.

Measurement:

• Measurement set up: see X-ray alignment
• Measure the intensity of the open beam. With new sealed tubes, fine focus, this value should be approx.:

	Mo	Cu
with monochromator	4500 cps	8000 cps
without monochromator (no beta filter)	7000 cps	14000 cps

Reset

When the goniometer program halts, it can be reset by the button on the front of the interface. A reset is also possible by switching off the power but this will also switch off the X-ray high voltage. See also the start-up sequence.

Detector HV adjustment

Because the detector amplifier tube will degrade in time the HV (which controls the gain) should be adjusted regularly (every 1-2 year). The detector has two HV settings:

• Hardware course setting in the goniometer, which is factory adjusted. This needs only be readjusted with a new detector or HV unit.
• Software fine setting, which can be used to compensate changes in time. The range is large enough to accommodate Cu and Mo without changing the hardware setting. The default is approx. 50 for Mo or 150 for Cu.
• Measure the primary beam without beamstop with a standard absorber and 20 kV (Cu) or 30 kV (Mo) 10 mA (see safety). When you have changed the tube, we advise to measure in the first stage of X-ray alignment, without monochromator, to prevent confusing with misalignment.
• Disable the automatic gain adjust in : GONCON, CASPAR, M, FL
• First output FL and note the default settings
• Fill in till the question: do you want pulse shift correction on : N
• Change HV in GONCON, CASPAR till the intensity with LL = 100, WD = 250 is half the intensity with LL = low (Mo: 40, Cu: 30).
• Input the default values for LL and WD (see table below).
• Enable PULSESHIFT in GONCON, CASPAR, M, FL.
• The other detector parameters are fixed:
 

	GAIN	LL	WD
Mo	200	40	130
Cu	200	30	140

X-ray tube replacement

• See FR590 manual, chapter 4.2.2: Draining.
• The tube holder is designed for an A-version (short) tube. When using a B version (long) tube the 13 mm adapter must be used.
• If the removed tube is used again : first measure the Effic for later reference.
• With a different anode: readjust the detector HV.
• Realign the X-ray optics.
• Maintenance of the tube: See FR590 manual, chapter 5.3: X-ray tube.

Monochromator

1. First switch off the power of the X-ray generator.
2. The monochromator is fixed with screws from below the collimator stand.
3. First adjust the Tube-2Theta before mounting.
4. With the X-ray port: first adjust Tube-2Theta before mounting.
5. When not mounted in the right position the shutter will not open.
6. After changing: realign the X-ray optics.

Collimator

Beamstop

Second microscope (option)

Attach the microscope to the base of the goniometer. Make sure that it is perfectly vertical. Mount the test crystal and centres it, using the fixed microscope. Adjust the position of the second microscope as to get the test crystal in the centre of the reticule, with adjustments height and rotate. Lock the adjustments. The microscope must be removed from the stand before operating the goniometer. The stand does not interfere with any axis movement and can be left to the base of the goniometer.

Standard polaroid cassette (option)

Position the goniometer with the POLA command. The polaroid cassette may only be used in this position.  Mount the Polaroid cassette on the Omega axis.  Loading the film : Set the LOAD/PROCESS lever to LOAD.  Insert the film pack firmly with 'this side toward lens' away from the crystal.  Pull out the film pack until it stops. Pull the EXPOSE knob out. The film is ready to expose.

Axial polaroid cassette (option)

• Position the goniometer with the POLA command. The polaroid cassette may only be used in this position. When Theta is accidentally moved from this position the cassette arm shifts back.
• Mount the Polaroid cassette on the goniometer base, opposite to the X-ray tube.
• Loading the film : see standard polaroid cassette.

Fuses

Lamp

O-ring seals

• Between X-ray tube and tube holder: part number 2132.017.
• Water hose connection: part number 2132.018.

Test crystal

• For goniometer head ECON and Eucentric: part number 0516.351
• For goniometer head XYZ: part number 0516.352

When the safety doors open the shutter will close for safety. When at that moment the shutter does not close completely the HV will not be switched off as under all other circumstances will happen. To prevent this problem an electronic component (IC) must be replaced. This is not difficult and can be done by an electronic engineer. It is not needed for KappaCCD/CCD on a rotation anode generator.

• Order (for free) the component called INT2E, part number 0540.656.
• Open the goniometer interface from the front.
• Remove the board with the three large connectors. First make a note which cable connects to which connector.
• Replace the component with note INT2A with the new component called INT2E. The component can be removed by pushing it with a small  screwdriver under it. Take into account the position (a small hollow at one end). Take care that not one pin is bend an not connected
• You can also send this board to your local service for replacement.
• Remount the board.

Ceramic tubes

When using Siemens ceramic tubes with the Nonius HV connector an isolation tube is needed. This must be placed as shown below:

• Start-up and communication problems
• Collision and maximum angle switch
• Zero finding
• Software error messages
• X-ray intensity problem
• Shutter does not open
• Phi limits: switch off/on the interface (Phi rotated to many times 360 degree)

• With PC-DOS program, endless message: POLL: Unable to drop message due to data overrun
• This message can occur, even during several minutes, but at the end it should stop and you can proceed
• If not: start all over again from power down (including the Goniometer interface).
• With SGI-Indy computer: It is know that the RS232 port of the Indy is sensitive for electrical disturbance, like power problems.
• When the computer stops at: "Connection to CAD4 ..." and the pocket terminal says: "connecting to the host computer", try the other RS232 port 2:
• Login as CAD4
• Command: cd data0/config
• Command: mv rs232_port.ttyd1 rs232_port.ttyd2
• Connect the small round RS232 connector one connector lower.
• If this helps, then other port should be repaired by SGI.
• Be sure to use the right start-up sequence
• With
• When you feel confident to check the electronics: open the Interface box from top.
• On the back board all red lamps (LED's) must be on.
• Measure the +5V on the test pins on the back board. It should not be lower then 4.8V. If it is not::
• Disconnect and connect the front connector on the power supply: the upper one on the right.
• If this does not help, probably the power supply is defect.

The anti-collision software prevents the goniometer from colliding with the collimator holders or the axes to run past their limits. When a collision takes place because of unexpected circumstances, like a technical error, it is sometimes possible to return:

1. The pocket terminal shows a special menu: choose the axis you want to position with F1-4.
2. First press the overrule button on the goniometer (near the connectors).
3. Then press simultaneously the pocket terminal < or >. Take care not to run the goniometer further into collision.
4. As soon as the collision switch is released, the goniometer starts to zero-find.

Does not find zero during start-up

Very frequent zero finding during measurements

• Problems with +5V power supply. When you feel confident you could check the electronics
• Technical error in axis positioning. Please mention the program and operating system you are using and Service will ask you to read out some internal test data.

• Check the EFFIC measurement and compare it with earlier measurements. Mostly a low intensity is caused by the X-ray tube.
• Check the alignment of the goniometer.
• X-ray measured while the shutter is closed: This is  mostly an oscillation of the detector amplifier caused by bad connection.
• Check if the detector parameters in the GONCON / CASPAR file are about the same as in the delivery table.
• Switch off/on the Interface and start again.
• Disconnect and reconnect the two connectors on the detector.
• Disconnect and reconnect the black (detector) cable between goniometer and Interface.
• Open the Interface and remove and remount the lowest (detector) board
• Rotate Theta and move the detector cable by hand: : if the oscillation stops if can be a broken wire in the cable.
• Disconnect the round (HV) connector on the detector: does oscillations stops?

• The red shutter lamp goes on (temporary) but the shutter does not open (green shutter lamp remains on, so both lamps are on). This error is mostly caused by a safety error. Check in which part is the error:
• Shift the collimator backwards as far as possible with the right pin position.
• Override the enclosure safety with the key (flashing lamp). If the shutter now opens, check if all the doors are closed.
• If safety door switched does not work: put thin plastic under the doors, so they get higher, closer to the (magnet) switches.
• Place new lamps in the red shutter on lamp.
• Below the collimator holder there are two connections with a yellow and black wire (the collimator safety). Short circuit them and check if the shutter opens. If so: inform the Service department. For safety : never use this short circuit permanent.

BRUKER AXS B.V., P.O. Box 811, 2600 AV Delft, The Netherlands, Tel: 31 15 2152400 Fax: 31 15 2152500.

Service: see our web site: www.bruker-axs.com