N6781

The CAEN Mod.N6781 is a a 1-unit wide standard NIM module integrating 4 Independent 16k Digital MCA for digital nuclear Spectroscopy. A version with 2 independent 16k MCA is also available (N6781A). It is ideally suited for high energy resolution semiconductor detectors, like HPGe and Silicon, connected to a Charge Sensitive Preamplifier (CSP) but it can also properly work directly connected to a PMT with inorganic scintillators (Nal, Csl) and other types of crystal, provided that the pulse shape is exponential and the decay time is long enough (typ. > 200 ns).

The module houses 4x (or 2x) 100 MS/s 14-bit waveform digitizer (based on 724 series) on single-ended inputs with BNC connectors, featuring 4-step software configurable input range and adjustable DC offset via a 16-bit DAC on each input in the full range.

The N6781 is equipped with a FPGA featuring the real-time Digital Pulse Processing for Pulse Height Analysis (DPP-PHA firmware) making the module a spectroscopy acquisition system providing energy (i.e. pulse height) and timing information as well as portions of the waveform and other traces for the fine tuning of the PHA settings.

Thanks to its two independent inputs of simultaneous acquisition, the N6781 is able to manage coincidences and anticoincidences between a pair of detectors, allowing the user, for example, to easily take advantage of background rejection or anti-Compton techniques.
The module has been designed to operate as a scalable multi-input, multi-board acquisition system, offering synchronization capabilities.

The N6781 houses USB 2.0 and Optical Link interfaces. USB 2.0 allows data transfers up to 30 MB/s. The Optical Link supports transfer rate of 80 MB/s and offers Daisy-chain capability. Therefore, it is possible to connect up to 8/32 MCA modules to a single Optical Link Controller (Mod. A5818/A4818).

Operating modes:

• “Pulse Height Analysis (PHA)”: pulse height histogram (1k-2k-4k-8k-16k) built at software level.

• “List mode”: pulse height and time stamp for each event.

• “Oscilloscope” mode: input and internal filters waveforms.

Software available (Windows and Linux):

CAEN provides drivers for all the different types of physical communication channels, a set of C and LabView libraries (CAENComm, CAENDigitizer, CAENDPP), demo applications and utilities:

• CAENUpgrader: tool that allows the user to update the firmware of the digitizers, change the PLL settings, load, when requested, the license for the pay firmware and other utilities.

• MC² Analyzer: Digital MCA Data Acquisition and Analysis Software designed for CAEN Digital Multi Channel Analyzers and Digitizers running Pulse Height Analysis (Windows only).

• CoMPASS: Multiparametric DAQ Software for Physics Applications designer for CAEN Digitizers running Pulse Shape Discrimination and Pulse Height Analysis, CAEN Pulse processors and MCAs.