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  EFFICIENCY ENHANCING COATINGS ON MCP     <<back to info page
           
 

Efficiency enhancing coatings on MCP for photon detection can now also be obtained for the RoentDek detectors. We have recently proven our ability to produce and safely deliver a coated MCP set for UV and soft-X-ray detection to a customer.

As known from the literature coatings like CsI significantly enhance the detection efficiency for photon energies between UV wavelengths and several keV but are rather difficult to handle [Fraser et al., Nucl. Instrum. Meth. 224 (1984) 272-286].

It could be shown that a DLD80 detector with CsI coating delivered to the Soft X-ray Spectroscopy Laboratory of RIKEN, SPring8, Japan provides high and stable quantum efficiency for X-rays of 1 keV energy. The absolute quantum efficiency was not measured but from comparing detection rates with and without a repelling field for the secondary electrons the efficiency enhancement is within the expectations.

The figure shows flourescence lines from a soft X-ray-spectrograph at KEK, Tsukuba.
 
 



Raw image of the grating output onto the detector plane
 
 



Obtained X-ray flourescence spectrum after data calibration. The rate was only about 25 X-rays/sec
 
 

The new detector allows coincidence experiments involving soft-X-ray photon detection from gas phase and solid targets.

Also, by combining pulsed Synchrotron radiation with the good time resolution of the RoentDek DLD detectors one can reduce background from stray particles and dark counts. So it is now possible to analyse very weak lines that would otherwise be obscured by background.

RoentDek can supply different coatings for UV, VUV and soft-X-ray detection purposes. As the handling of the detector usually demands short intervals of exposure to ambient air only coatings such as CsI, KBr or MgFl2 can be produced for open detectors, i.e. those having a certain tolerance to water vapor. It could be demonstrated that the shipping and standard handling processes of a DLD detector by the user does not degrade the coating if some precautions are taken.


New Image Intensifiers

For wavelengths smaller than VUV (near UV, visibile, IR) sealed detector tubes, so-called image intensifiers, can be used. Usually such image intensifiers are read out using an optical screen and the time information is lost. RoentDek can supply electronically coupled delay-line or wedge-and-strip read-out systems for special image intensifiers (patented technique) that presume the timing information for each photon.

These new image intensifiers with high resistive screen for (electronic) coupling with special RoentDek anodes (follow this link for details) are produced by Proxitronic GmbH in Bensheim, Germany (http://www.proxitronic.de)
 
 
 
 

Such detectors could also be used for position and time resolved high energy X-ray detection if such a special image intensifier is combined with a scintillator window (http://www.photek.com).

Currently we investigate the possibility to detect thermal and high energetic neutrons with neutron sensitive scintillators coupled to the novel image intensifier for time and position sensitive image read out with RoentDek anodes.

For more information please inquire at:


 
  by Dr. Ottmar Jagutzki, May.2003