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PRODUCTS
 

RoentDek's major development is a position and time sensitive Microchannel-plate (MCP) detector system with delay-line read-out anodes for advanced particle and photon counting. Please find details below.

If you are interested in a special detector solution which is not listed but might be provided by us, please inquire.
We are also able to suggest and provide advanced spectroscopy systems including time-of-flight/imaging spectrometers (e.g. COLTRIMS) for specific tasks.
 
We can also provide solutions for the task of visible light detection in single photon counting mode. 
         
 

GUIDE TO THE OPTIMAL RoentDek DETECTOR SYSTEM

     
 
 
The RoentDek MCP detectors with delay-line anode apply an electronic particle (or photon) counting technique. The electronic circuits register digitally the information on the position and on the arrival time for each individual particle. The information is available in real-time and free of any "read-out noise" or blur, as known from CCD read-out and can be correlated with other recordings (or other detected particles) in real time. A detector system consists of several components: Detector heads, feedthrough with signal decoupling, power supply assembly, front-end electronics (amplifier and timing discriminator) and time-to-digital converter (TDC). In order to achieve a performance best-suited for your application, a few choices have to be made. This guide shall help you in these decisions. Before going into details you may refer to this document to verify if the detectors are compatible with your application and needs.
 
1  Detector heads:

A detector head of type DLD or HEX consists of the micro-channel plate (MCP) stack and the delay-line anode. The DET MCP detectors contain a metal plate behind the MCP stack (only timing pick-up).
The MCP stack usually features two (resistance-matched) micro-channel plates with pore sizes of typically 12.5 or 25 microns and a channel length-to-diameter ratio (L/D) between 80:1 and 40:1, stacked in so-called Chevron configuration. The MCP stack is operated in gain saturation so that every particle hit creates a distinct electromagnetic signal signature and a well-defined charge cloud, which is collected on anode. Due to the characteristics of the delay-line anode several electronic signals on distinct pick-up terminals are produced in a time sequence, which encodes the information on the position and absolute time of the particle impact. The time sequence is usually registered by a (TDC) after front-end electronics' signal shaping.
The standard product choices DLD40, DLD80 and DLD120 use chevron MCP stacks, the number denominating the (approximate) effective MCP diameter. Generally, larger detector heads will give better performance (even for the absolute position resolution). The DLD40 and DLD80 can be delivered with different MCP types (12.5 or 25 microns pore size) and can alternatively be equipped with triple (Z) MCP stacks for improving the ion-feedback characteristics. This can be relevant in advanced multi-hit applications. The required open area will usually determine the choice of the detector size, but the number of desired position pixels in the image (which depends also on the TDC choice) must be considered, too.
Detectors for multi-hit analysis (e.g. fragment imaging): The HEX option (HEX80 and HEX100) is designated for experimental situations where particle bursts ("multi-hit") shall be detected, i.e. it is likely that more than one particle arrives within a short (<100 ns) period.
Detectors with central hole: RoentDek can deliver detectors with a central hole, allowing a particle/photon beam to pass though the detector (option _/o). Those detectors are usually built with Hexanodes (HEX40/o, HEX80/o, HEX120/o) and have typically a 6.4 mm hole. They often require a special (user-defined) shielding tube.
Special MCP with improved performance characteristics or coatings (e.g. for efficiency-enhanced VUV/X-ray detection) can be incorporated in our detectors. It is also possible to build custom-designed, specially-shaped delay-line anodes (e.g. with an internal phosphor screen) and also delay-line anodes for one-dimensional read-out only.
Completely assembled and tested Resistive Screen MCP detectors with anode (e.g. DLD40X featuring an external LC-delay-line anode) for direct flange mounting can be shipped ready-to-use. These have the same imaging/timing properties as the (helical-wire) delay-line of the standard detectors and increased tolerance towards ambient magnetic fields.
Based on this technique TSCSPC-detectors for visible to near-UV single photon counting or scintillator screen imaging (RS-PMT25 and RS-PMT40) are available, incorporating detector heads produced by our collaboration partners Proxivision GmbH or Photek Ltd. Furthermore, TSCSPC-detectors can also be provided based on the helical-wire delay-line anode as encapsulated detector heads for visible and near-UV single photon detection (DLD40PMT and DLD80PMT) with a choice of photo-cathodes.
 
2  Feedthrough/Mounting:

It is recommended to order a FT12-TP-type vacuum feedthrough and signal-decoupling plug with the detector (for HEX-option: FT16-TP) because the signal decoupling and biasing of the detector is very critical for the performance.
Furthermore, a mounting gear for the detector head on and with a "Conflat" vacuum flange can be ordered, options _/100, _/150 and _/200, the numbers denominating the inner flange diameter in mm. Of course, the flange diameter must be bigger than the outer detector size as given in the product descriptions. Typically, the mounting gear included in these product options is for the largest fitting detector size, but it is also possible to order a feedthrough/mounting-gear on a larger mounting flange (e.g. FT12-TP/150s for a DLD40 on a Conflat flange with 150 mm inner diameter). If you need any special flanges or extra ports in the customarily offered flanges please contact RoentDek.
It should be noted that the standard "–TP" option will transform the intrinsically differential delay-line signals into single-ended signals with 50Ω impedance. It is possible to order the decoupling plug without this –TP option.
The DLD40PMT and DLD80PMT already contain a FT12-TP-type decoupling circuit. However, they might need an extra cooling housing, please contact RoentDek.
 
3  High voltage power supply

A RoentDek DLD or HEX detector requires 5 separate potentials (plus a sixth if a front mesh shall be independently biased) for operation. In most cases it is sufficient to supply the "MCP back" and "holder" contact with the same potential; and the BA3 floating battery box reduces the number of independent power supply channels needed to 3 or 4. Depending on the task it might be possible to operate the detector even with only 1 or 2 independent power supply channels (please contact RoentDek for details).
In any case, the power supplies should have enough range, stability and excess-current trip protection. Two versions can be delivered, the HV2/4 with two independent channels (require a NIM bin or the RoentDek SPS2 for operation) or the BIASET2. For applications with MCP front and MCP back on the same polarity, the High Voltage terminator is necessary as a voltage stabilizing unit.
 
4  Front-end electronics:

RoentDek offers customarily a set of amplifying/timing electronic circuit boards (DLATR) inside a 19" case with mains power supply, the ATR19. The DLATR board is a constant fraction discriminator (CFD) circuit with pre-amplifier. The ATR19 case hosts all inputs/outputs and controls for operating the boards.
Usually the ATR19 is equipped with 6 channels (3 DLATR boards) for DLD-type detectors or 8 channels (4 DLATR boards) for HEX-type detectors; in both versions, one channel is "spare" and available for the processing of an external signal, or a signal from a second detector (e.g. a DET40 timing detector with FT4-TP signal decoupling).
If the signals shall not be digitized with a TDC but with fast ADC system (fADC, see below), we recommend amplifying the signals from the FT12(16)TP-type signal decoupler by a FAMP8 and or FAMP1 module (possibly followed by a MIXA8). Also if a different CFD than the internal circuit on the DLATR board shall be used (e.g. the new CFD8), the FAMP amplifiers shall be used for pre-amplification. The combination FAMP8 and the new CFD8 (and TDC8HP) represents the optimal readout electronics of RoentDek delay-line detectors for advanced performance demands.
 
5  Digital read-out (TDC) 

The TDC choice is very important for the application. So far, the TDC is limiting some performance characteristics of the detector system like particle throughput and position resolution (and thus the number of pixels in an image, also depending on the active detector size).
Currently there is the choice of two TDC-types:
a) the HM1-B can be operated in several modes. It is mainly used for fast imaging or imaging&timing applications (not multi-hit) with DLD-type detectors and allows in the limit 1 MHz particle rate. The HM1-B's analog output can produce an on-line image on an oscilloscope screen (oscilloscope not included). The HM1-B has also an option to acquire up to 3 (multi-) hits at a particle rate of up to 15 kHz.
b) the TDC8HP is a module dedicated for high resolution imaging and for multi-hit acquisition. It can achieve a particle throughput over 100 kHz (CPU-dependent), but does not have an analog output option.
For detailed advice on the best-suited TDC choice for your application please contact RoentDek.
Advanced digital read-out:
For advanced applications (e.g. extreme multi-hit conditions) the use of CFDs and TDCs can become inadequate due to dead-time limitations and lack of desired information on the pulse height and shape of the detector signals. For such demands it is possible to record the signal sequence from the detector by a fast ADC system (fADC). RoentDek supports this technique with adequate front-end electronics (see above) and data analysis software (please contact RoentDek for details).
 
6  Auxiliary items:

If a complete detector system is purchased, it can be considered complete concerning all "special" items. Connection cables ("lemo") between electronic modules are included if both modules to be connected by the cables have been purchased.
Only standard SHV connection cables between the high voltage power supply HV2/4 and the feedthroughs are NOT included, but can be ordered separately. Standard tools as screw drivers or wrenches, which are necessary to assemble and mount the detector heads (the detector heads and mounting gear come as an assembly kit) and for adjusting the electronic settings are NOT included. Also NOT included is a PC for the TDC operation . However, the data acquisition software CoboldPC (for but without Windows OS) is part of the TDC delivery.
A fast oscilloscope (300 MHz) for single pulses is necessary for initial signal verification and performance control (trouble shooting).
For using auxiliary monitoring, operating several detectors in coincidence or correlating detector signals to external signals, additional pulse-shaping and multiplexing electronic circuits can be of necessary. The RoentDek products COIN4, MIXA8, NIM2ECL and ECL2TTL can be useful complementary electronic units in this respect.
  
7  Coincidence setups and COLTRIMS/spectrometer assemblies:

RoentDek is able to provide advanced setup for operation of two (or more) detectors and support the correlation between the detector signals and other recordings from the experiments.
COLTRIMS setups or custom time-of flight spectrometers can be assembled from standard components.
Since such setups are strongly application-depended it is necessary to contact RoentDek for details.