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  The RoentDek (RS-)DET40/75 timing detectors     <<back to info page  

Although RoentDek mainly specializes in advanced MCP detector systems featuring both spatial and temporal resolution for single particles/photons, our product portfolio naturally also contains adequate components for “timing-only” MCP detectors (e.g. with “metal anode”) as available from major MCP manufacturers. The metal anode can also be replaced by a phosphor screen.
For those detectors, RoentDek can not only contribute low-ripple high voltage supplies (e.g. the HV2/4 series) and adequate signal decoupling circuits (type FT4TP): our amplifiers, discriminators and analogue or time digitizers combined with RoentDek software, experience and expertise on how to use and operate timing/counting detectors in various applications will complement a high-quality detector to an elaborate TOF-spectroscopy instrument.
Some units like the LET1+ timing discriminator have been especially developed for such purposes and can bridge the gap between readily available detector equipment from the MCP manufacturing experts and the need for a complete analyzing device, ideally even tailored towards a specific application. RoentDek has specific expertise for such system integration tasks.

Moreover, RoentDek also provides custom-made MCP timing detectors likes the DET40/75, based on well-matured components adopted from the delay-line detector series, which surpass “standard” metal anode detectors in features like robustness, adaptiveness and handling comfort. Custom-mounting schemes allow placing a detector also at considerable distance from feedthrough/mounting flanges.


Left: DET40 with provisions for mounting a custom phosphor screen in the rear. Right: RS-DET40 mounted on a Con-Flat CF-flange with image-charge transparent timing anode. The detectors are bakeable up to 150°C.


Signals for optimized connection schemes at short distance between DET40 and FT4 feedthrough flange have rise time of < 1 ns with FWHM of < 1.5 ns. Special MCP geometries are available, i.e. with central hole.


The DET40/75 can also be used as a current amplifier in so-called total yield operation: by measuring the MCP’s output current on the anode with a pico-ammeter the total particle flux on the detector input over a wide range down to the single particle counting regime can be determined  
Also, there is a special type of transparent timing anode that allows placing custom read-out circuits behind the detector, either in vacuum or, in combination with a RS-DET40/75, right on air-side of a flange-mounted detector.
Timing electronic schemes:
For all MCP timing detector applications RoentDek supplies the same type of FT4TP feedthrough assembly (with or without mounting device) which takes care of high voltage input (e.g. from HV2/4-type supplies) and signal decoupling for output to electronic recording devices. Depending on the actual application there is a choice of read-out electronics:
For “simple” counting applications at quasi-continuous rates up to 2 MHz and with no or only modest temporal resolution demand, the LET1+ is an economic solution. It provides a digital output signal (NIM or TTL) for counters like the RoentDek RM6 or TDC timing devices.
If high temporal resolution (down to 100 ps FWHM) is required a combination of FAMP1+ and CFD1 is appropriate, followed by a high precision TDC (e.g. the TDC4HM or TDC8HP). Even higher temporal resolution can be obtained by using a fast analog digitizer like the fADC4.
For bunched operation, i.e. whenever a large number of particles during a short period are to be detected, a combination of FAMP1+ and fADC4 is the optimal choice. This read-out scheme expands operation even to particle fluxes when several particles arrive simultaneously and individual signals overlap. This bridges the gap to the “current mode” of MCP when individual particle detection turns into recording of a fluctuating current.

As variation of detectors with “simple” timing anode RoentDek can alternatively provide structured anodes with multiple independent detecting elements. An example is the DET40_5 with five independent anode elements (Pentanode). Signals from each element can be picked up via rear-side contacts. The concept can be expanded to any custom-defined number of elements (“pixels”) with variable shapes.



Front and rear view of a Pentanode mounted to the rear-side MCP carrier ring


Depending on the number of read-out elements RoentDek can provide adequate signal feedthrough and decoupling solutions based on the FT4/12/16TP product range, followed by standard timing electronics circuits or advanced read-out via fast ADCs (RoentDek fADC4) to allow for imaging applications with spatial resolution well below pixel size, employing charge-centroiding algorithms.

The DET40/75P with phosphor screen:

RoentDek offers the DET40/75 timing detectors optionally with phosphor screen. Compared to "industrial-grade" assemblies RoentDek supplies devices for high-end scientific applications. This means that the MCP stack is of same quality and specs as employed for single particle counting and imaging. The screen is of selected quality with choice of material. It does not need an aluminum cover so that decent light output is already achieved at comparably low bias. This makes handling, mounting and operation of the detector user-friendly (e.g., no excessive high voltage needed). The detector can be mounted anywhere inside the vacuum vessel as long as the screen can be viewed by a camera through a window. The assembly is modular, components can easily be replaced. It is possible to combine particle counting/timing with recording an image on the screen.


Typical image performance obtained with a DET 40P

RoentDek also supplies detector mounting gear and flange with high voltage feedthroughs and embedded window or viewport.



DET40P on window flange wih high voltage feedthroughs.



The RoentDek DET assemblies with phosphor screen anode can also be operated as timing detectors (pickup of time signal) and individual single particles in an image frame can be “counted” by an advanced “centroiding” image read-out algorithm based on the CoboldPC software, as long as the particle rate is low enough for single particle MCP operation mode. The picture on the right shows the footprint traces of individual particles during a short camera exposure of the phosphor screen on a DET70P. Summing up all camera frames during a measurement period eventually produces an analog image. Spatial resolution is determined by the size of the footprints, here < 0.3 mm FWHM. By applying a “centroiding” algorithm, the spatial resolution can be significantly improved.




Above: Projection of traces from a DET70P phosphor screen of two individual particles, imaged by a frame camera and digitized with CoboldPC software. The footprint size limits the spatial resolution unless a “centroiding” algorithm determines the “center-of-mass” position for each footprint with great precision.



Analog image of a test mask (left) and the same when applying a centroiding algorithm on individual traces.