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Features

• Simultaneous amplitude measurement and pulse shape analysis for each channel.
  
• Pulse heights measured with up to 16 bits accuracy (i.e. 64K spectrum length).
  
• Dead times as low as 1 microsecond per event are achievable (limited by DSP algorithm complexity). Events at even shorter time intervals can be extracted via off-line ADC wave form analysis.
  
• Digital constant fraction algorithm measures event arrival times down to a few ns accuracy .
  
• Programmable gain, input offset, and peaking times between 0.25 and 40 microseconds.
  
• Programmable pileup inspection criteria include trigger filter parameters, threshold, and rejection criteria.
  
• Supports multiparametric data acquisition of events distributed over many detectors as well as independent spectrum acquisition.
  
• Waveform capture up to 100 microseconds in length for each channel.
  
• On-board MCA memory for data taking or for monitoring when in multiparametric mode.

Specifications

• Signal Input (Analog) - Works with common reset or resistor feedback preamps of either polarity.
  Impedance: 50 Ohms, 90 Ohms, 250 Ohms, and 1k Ohms - jumper selectable
  Attenuation: 1:21, 1:12, 1:5 and 1:1- jumper selectable
  Voltage Range: +10.0 V to -10.0 V standard
• Inputs (Digital)
  Gate Input: Analog input for Compton suppression. Can alternatively be configured as digital I/O.
  Sync Input: (Special Order) TTL logic input to control time resolved data collection, including scanning and "phase locked loop" applications.
  HV Inhibit: TTL logic input. BNC connector, jumper set active HI or LO.
  
• Interface:
  USB: Universal Serial Bus 1.0
  EPP: Enhanced Parallel Port, defined by IEEE specification 1284, standard.
  OEM: Auxiliary 25 pin programmable bidirectional I/O connector optionally available.
  
• Digital Controls (Set via EPP Port)
  Gain: 50X coarse gain (2% accuracy), fine gain controlled by 16 bit DAC.
  Dynamic Range: 5MeV for preamp gains of 100mV/MeV; more with attenuation.
  Shaping: Triangular/Trapezoidal. Peaking time and dwell set independently : 50ns - 45 microseconds in small steps. Adjustable dwell time may be used to eliminate ballistic deficit effects.
  Pileup: Set fast channel filter time, pulse detection threshold, and fast channel pileup inspection test limits to achieve best results in each situation.
  Spectrum: 1K-64K bins, 32 bits deep (4.3 billion counts per bin)
  
• Data Outputs (via USB or EPP Port)
  Spectrum: 1024-65536 channels standard, more with optional extra memory.
  Other: Collection livetime; Event-by-event waveforms; input/output count rates; Compton coincidence rate
  
• Control Outputs (TTL via OEM Port)
  Control Signals: sends or receives TTL control signals via optional OEM connector, to create flexible custom interfaces to external instruments or industrial equipment. Lets custom DSP codes integrate the DGF Polaris into dedicated spectroscopy applications.
• Power Outputs
  Detector Supply: High Voltage +/- 5kV, SHV connector, push-button on/off, front panel adjust, 60 sec. on/off ramp standard . Other options available.
  Preamp Supply: standard preamp power voltages +/- 24V and +/- 12V, each to 100 mA.
  
• Power Requirements: 110 V at 0.2 A 50/60 Hz or 220 V at 0.1 A 50/60 Hz, specify at time of order.
  
• Dimensions: 8.6" W x 7.0" D x 3.8" H.
  
• Weight: net 5.0 lbs., shipping 8.0 lbs.
  
• Manual: Hardware and software manuals provided with each instrument.
  
• Software: The Polaris comes with all necessary software and firmware included:
  FiPPI and DSP firmware, version dependent on application
  Polaris Viewer host control software
  C libraries for OEM applications also available

Performance

• Energy resolution: Comparable to best analog units. DE degradation at high count rates is typically dominated by imperfect pole/zero cancellation in the preamplifier.
  
• Dead time:
  Filter dead time: (2 * peaking time + flat top time)
  Additional dead time due to DSP data reading, for the typical case of reading pulse height data and 32-point traces for N channels, 1 <= N <= 4: 1.7 microseconds + N * 3.0 microseconds - peaking time.
• Event processing time:
  Basic pulse height reconstruction (dE/E = 0.25%, FWHM): 1.0 microseconds + N * 3.6 microseconds
  Pulse shape analysis for improved energy resolution: adds N*2.75 microseconds
  Pulse shape analysis for CFD timing: adds N*2.00 microseconds
  Histogram to DSP memory: adds 0.35 microseconds + N*1.40 microseconds
  The last three operations can be set on a channel-by-channel basis. Event raw data acquisition is done in a DSP interrupt routine and can interrupt event processing, which resumes afterwards.
  
• Data acquisition:
  Spectra: 64K words of spectrum memory. Lower limits for spectrum entries and bin widths are programmable.
  Waveform record: lengths from 0 - 102.4 microseconds for local processing, or export to host.
  Statistics: records run duration, event rate and both live time and input rate.

Note: The following quantities are from a particular detector (an Ortec Iglet-x) and may vary some-what for other detectors

• Count rate precision: 0.1%, or limited by statistics
  
• Peak stability with rate: 0.05% up to highest ICR.
  
• Integral Nonlinearity of Energy: = 0.1% of full scale.

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http://www.xia.com/DGF_Polaris.html, last updated January 2006.
© XIA 2006