dactylos - python interface to CAEN N6725 digitizer

dactylos? - dactylus is greek for finger, which is digit in latin ...

CAEN N6725 digitizer API

CAEN provides a well written, functional style C library to interact with its digitizers. However, especially for the rapid development of lab environments, this might be a bit of a hindrence since it is comprehensive, thus requires some time to accquaint oneself with the specific features of the digitizer. This library - especially since it has pybindings - allows for quick setups of this CAEN digitizer in the lab and obtaining first results.

• Configure the digitizer via .json config file

• Save data to .root files

• Allows to save the waveforms in root files as well

• Basica analysis capabilities for energy spectra

CAVEAT - the CAEN N6725 is a multifunctional instrument. This software allows to access a fraction of its functionality. It is not guaranteed, that data taken with this software looks either sane nor as clean/low noise as it is in principle possible

CAVEAT - it is not guaranteed that this software is neither harmful nor useful (See the attached GPL licensce

Requirements

• CAEN Digitizer libraries/drivers

• pybind11

• The root analysis package from CERN (modern root > 6.00 recommended)

• Cxx 11

Installation

The build can be either performed with CMake or the shipped setup.py file. The setup.py method will invoke cmake, but for more control, cmake can be called directly as well

Usage

Two binaries are provided, one for data-taking and another one for analysis of a (possible X-ray) spectrum

A word about DC offsets and trigger thresholds

Setting the DC threshold shifts the offset of the digitizer bins. E.g for a 50% DC offset and a dynamic range of 0.5Vpp, 0V will be at 8192. For an offset of 100%, 0V will be at 0 and for an offset of 0% 0V will be at 16384. The confusing part here is that the "natural, middle setting" is 50%. This also means e.g. a 10mV signal will saturate the digitizer for a 0% DC offset. There are 2 different trigger thresholds. One is configured for the digitizer, one per channel, this is done via set_channel_trigger_threshold, the other one is part of the energy filter and set through the DPP_PHA_Params struct.

• Channel threshold: The waveform has to "reach" a certain bin, baseline dependent

• Trigger threshold in DPP_PHA_Params: This trigger threshold is NOT a waveform time-over-threshold, but is for the RC-CR2 signal. It is basically the minimum energy of the energy filter. Thus means it is independent of the DC offset, as the DC offset affects the baseline and the energy filter is independent of the baseline level.

Different firmwares

There are different types of firmwares. One is the DPP-XXX firmware, which allows digital pulse processing on the digitizer board. The dactylos software supports the DPP-PHA firmware.

The 'standard', free firmware is the waveform recording firmware, this is supported by the dactylos software as well [currently in development]