The XBPM 4 is a 4-quadrant beam position monitor suited for hard X-ray synchrotron beam lines. It is ultra-high-vacuum (UHV) compatible, can remain continuously in the X-ray beam and allows monitoring the position of the X-ray beam in real time with a sub-micron precision. The XBPM 4 is available with two different active areas to fit into most beamlines and is very simple to install and to operate.

Principle:
The XBPM 4 is based on a very thin CVD diamond membrane. The transmission of the X-ray beam generates charge carriers in the diamond layer and hence a photocurrent is induced. With an external picoampere meter, this photocurrent can be measured for each pad. The difference of photocurrent between pads over the total current gives the signal, which can be calibrated to provide position information.


Applications:

• Beam intensity monitoring after monochromator
• Automatic beamline alignment after change of diffractometers
• Online feedback
• Pink beam monitoring

Technical specifications

Sensor	CVD diamond membrane
Sensor thickness	10 µm
Transmission	97% at 5 keV
Framing rate	~1 kHz (depends on read-out setup)
Bias voltage	~10 VDC
Large area XBPM4-L
Pad size	4.5 x 1.5 mm
Gap between pads	20 µm
Total active area	9.0 x 3.0 mm
Window size	9.6 x 3.6 mm
Small area XBPM4-S
Pad size	2.0 x 1.0 mm
Gap between pads	12 µm
Total active area	4.0 x 2.0 mm
Window size	4.6 x 2.6 mm
Cooling	Not required
Dimensions	~ 40 x 30 mm
Weight	~ 10 g