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  WHAT RoentDek DETECTORS CAN (and cannot) DO
 
 
 
 
 
 
If you are interested in RoentDek products please refer to the product description sheets and/or to instructions on the RoentDek website for learning how to combine individual items into a detection system for a specific task. More profound information on details may be found in the manuals section. Since the detector systems are modular and different combinations yield a variety of performance options, it is strongly recommended to contact a RoentDek employee directly for advice on product combinations most appropriate for your specific application, in combination with lab equipment that may be readily available at your site. You can request to receive a price list or quotations from your local supplier (or from RoentDek directly, if none is appointed for your region) at any time.

Before that you may review the following general facts about what the detector systems can do and what they cannot do. Although the following is written for delay-line detectors, most of it is valid for DET (timing-only) detectors as well. The listings may not be complete but will give you basic reference for further considerations.

What the RoentDek delay-line detectors can do:

  • Detect single atomic particles, molecules or photons (all summarized as “particles” from now on - see a list of particle species with decent quantum efficiency).
  • Simultaneously determine position and arrival time for individual particle hits with < 0.1 mm resp. < 1 ns precision, with continuous rates of at least 1 MHz.
  • Correlate particle hits on different detectors with external parameters or trigger signals (coincidence), or several subsequent particle hits on the same detector (Example: COLTRIMS).

What RoentDek delay-line detectors can NOT do:
  • Operate without decent (see below) vacuum environment (unless sealed).
  • Operate in magnetic fields beyond a certain strength (see below).
  • Operate in cryogenic conditions (see below)
  • Detect particles if the rate continuously exceeds a certain total number or a certain local number per detector area (see below)
  • Detect particle showers above a certain instantaneous flux (rate) even if the average rate integrated over a longer period (i.e. few seconds) is modest. However, the RoentDek detectors have certain “multi-hit” abilities (especially with Hexanode) which make them superior to other single particle counting methods like for example charge-sharing anodes. For detailed information please contact RoentDek.
What are the typical detector performance and operational limits?
  • Temporal resolution: 100-200 ps FWHM
  • Spatial resolution:        < 0.1 mm RMS
  • Overall Linearity:          < 0.3 mm (<0.1mm for Hexanode)
  • Count rate:                     average up to 1 MHz, locally: < 10 kHz/mm²
  • dead time:                      35-150 ns depending on detector size   (DET: 10 ns, Hex: please inquire)
  • Detection efficiency: see a list of particle species

Note, that the detectors can yield even better performance for optimal electronics choice and under well-tuned operational settings.

Optimal performance (near the specs limits) can only be expected

  • if the detector is installed and operated within its specifications,
  • if operational parameters are adjusted according to the manual,
  • in absence of interference from external noise sources and
  • as long as the MCP stack performs normally (MCPs are “consumables”, please see below).
Therefore these specs cannot be considered as “hard” specs and will also depend on the detector type and the electronics setup that is used.

Performance specs of RoentDek delay-line detectors that cannot be guaranteed at all:

If a customer’s application requires “hard“ specs on dark count rate, life-time, quantum efficiency, rate tolerance, pulse height, minimum gain, gain uniformity and stability it is necessary to submit these to the MCP manufacturers because it is basically the MCP stack quality that defines these specs. 

Typical
dark count levels of those MCP stacks provided through RoentDek are a few counts per second and square cm plus spurious local “spots” (often near the edge) with emission of a few counts per second. The gain uniformity and pulse height distribution is typically sufficient to achieve a uniform response over the active detection area.

What compromises the detector performance
  • Operation at too low MCP gain
  • Operation in high noise environment i.e. electromagnetic noise from turbo pump controllers, high voltage pulse switches (e.g. Pockels cells) and noisy mains power.
  • Presence of ground loops or inferior ground connections.
  • Operation in cryogenic condition (reduction of count rate tolerance for standard MCP)
  • Operation in B-field > 0.5 mT (> 5 mT for Resistive Screen detectors, > 500 mT for DET)   
In the following a few facts are summarized that would not only compromise the detector performance but may also lead to premature aging, wear-out or permanent performance loss or may seriously (and sometimes instantly) damage a detector. The list may not be complete:
  • Exposure to > 450 Kelvin or < 150 Kelvin, even when under vacuum conditions and unbiased → damage (unless unit is especially approved for increased thermal stress tolerance up to 600 Kelvin)
  • Any significant heating or cooling in ambient air → damage (thermal oxidation resp. condensed water deposition when cooled below dew point)
  • Mechanical shocks/stresses → damage
  • Physical contact of solid particles with anode wires or MCP surfaces, including dust → permanent performance loss or damage
  • Storage in humid air → permanent performance loss or damage (if exposure is prolonged)
  • Exposure to certain fluids/solvents and vapors (which includes moisture from ambient air) → permanent performance loss or damage
  • Operation in poor vacuum conditions → damage (> 0.1 Pa) or wear-out (> 1 mPa)
  • Exposure to normal air while the MCPs are still warm after bake-out→ damage.
  • Electrostatic discharges due to erroneous voltage settings or unsufficient clearing between biased detector parts and solid parts in the vicinity → damage, may also damage electronic units
  • Corona-type discharges (“glow”) for the same reasons → premature aging or damage
  • Presence of strong UV light or charged-particle sources in the vicinity of the detector, e.g. engaged ion gauges or ion pumps → premature aging or damage
  • Accumulated exposure to keV (or higher) particles (even when not biased) → wear-out
  • Exposure to excessive particle rates when biased → wear-out or damage
  • Continuous operation at the limits for steady operation → wear-out
  • Operation at excessive MCP bias voltage → wear-out or damage
What a customer should consider before ordering:

Make sure that the ordered parts, when combined with components that are already available in your lab, will form a complete system. When in doubt please contact a RoentDek employee. RoentDek can offer all necessary parts that form a complete system. However, “standard lab equipment” will be required to verify and operate the system, such as a PC and an oscilloscope. Unless especially ordered the following things are explicitly not included:

  • PC to operate the hardware/software which handle the data transfers from/to devices like TDCs, ADCs, USB-I/Os. Please refer to the specification for PC and operation system in the description sheets/manuals or contact a RoentDek employee.
  • An oscilloscope with at least two channels and a bandwidth  of > 200 MHz to verify the detector operation, with adequate cables and adapters to access monitoring outputs on the RoentDek electronics units (usually “Lemo 00/250 NIM-CAMAC” coaxial sockets).
  • Multimeter, standard tools, vacuum equipment, gaskets, nuts&bolts to mount and operate the detector in an appropriate vacuum environment.
  • Mains cables, High Voltage cables (usually SHV) and connection cables (usually of type “Lemo 00/250 NIM-CAMAC”) between electronic modules or to operate certain modules. A minimum set of the latter may be included if a complete system of several components has been ordered. When in doubt please contact RoentDek.
  • NIM-crate may be required by some modules.
  • Signal pulse generator such as the RoentDek APG1 as or a rate meter like the RoentDek RM-6 may be required for some (optional) system performance checks.
  • Additional NIM-Logic modules like the LogX may be required for signal gating or multiplexing.
  • Remote control devices like the USB-IO1 as may be required to access some (optional) remote control/data logging options of modules.
  • In case you want to use other high voltage supplies than those provided from RoentDek please note that these should feature low ripple, certain emergency shut-down functions and a ramp speed limit.
This list may not be complete.

RoentDek has a number of add-on devices in its product portfolio and can also provide approved third-party products to fill in the gaps between your lab infrastructure and the standard parts provided by RoentDek to form a completely operational system for your specific task - please inquire with a RoentDek employee.

Please also refer to the conditions defined for delivery reception and customer’s tasks for system assembly (see below) before making the final choice of product combination and options.

When you receive a package from RoentDek
  • IMMEDIATELY check the condition of the shipped box(es) and whether the number of parcels is in accordance with the number noted on the packing list (if no number is explicitly noted the shipment will contain only one parcel). If there are signs of transport damage or a parcel seems to be missing, claim this IMMEDIATELY to the shipping company and take photos. Failure to do so will waive your rights to get compensation. Neither RoentDek nor the chosen shipping company nor a shipping insurance company will be responsible for compensation claims without proof that the transport damage or incomplete delivery was regularly, completely and instantly reported. For regulations on how to report a transport damage accordingly please check with the transport company. Also inform RoentDek about such an issue.
  • Unpack the shipping and report about missing items or damaged/sub-standard items within one week after receipt to RoentDek. Do not dispose of the shipping containers or any of the packing materials inside before you have verified completeness and condition of the parts (RoentDek may in exceptional cases agree to extend storage of MCP in sealed containers after receipt. Keep records of any communications in this respect.). RoentDek keeps records of all parts that are packed into the shipping containers. If you are not able to unpack the goods within this period please inform RoentDek about this within one week after shipment. It may then be possible to negotiate an extension of the period. RoentDek will not be liable for replacing parts that are reported missing after this period.
  • Do not unpack the (sealed) MCPs before having read the “Handling Channel-Plates“ Instructions which can be found in the “manuals” section of the RoentDek web site.

What you have to perform when assembling the system for first use.

Since our systems are of modular nature and must be fitted to existing lab equipment, we will not ship a system readily functional. It has to be assembled. Some product parts such as the detector head need on-site assembly tasks because a few very delicate parts like the MCP stack cannot be mounted before shipping (exception: bolt-on systems and sealed photon detectors). For regular DLD and HEX-detctors the MCP have to be inserted by the customer. Prior to assembly the MCP must be stored in an approved way (see manual). Some mounting tasks can be delicate but are described in the manual in detail, mentioning the amount of expertise needed and pointing out hazards when following the assembly steps. RoentDek offers certain services to assist the customers in these tasks, from shipping some products in a higher-integrated state to on-site assembly assistance/training by a RoentDek employee.

 
 

For more information please inquire at: