April 16, 2024 Dataset Open Access

High-count rate photon detection with scintillators coupled to photomultiplier tubes and fast digitizers

García Rivas, Iris; Fernández Prieto, Antonio; Kögler, Toni; Roemer, Katja Ellen; Hueso González, Fernando

This repository contains raw experimental data acquired during the gELBE beam time performed in October 2023 under proposal number 23203137-ST, at Helmholtz-Zentrum Dresden - Rossendorf.

In this setup, a bremsstrahlung beam of up to 12.5 MeV energy in 13 MHz pulses irradiates a CeBr₃ scintillation detector (by Hilger®) of Ø 1'' x 1'', coupled to a Hamamatsu® R13408-100 PMT, custom voltage divider and shaping electronics, and a commercial digitizer (SFMC01+SIS1160) by Struck®, containing an AD9689 chip that supports a data sampling rate of 2.5 Gsps and 14-bits. This detector is developed in the context of the coaxial prompt gamma-ray monitoring method [1], where very high count rates are expected [2]. The dead-time-free data acquisition is programmed in-house using ROOT [3]. In addition, a plastic scintillation detector (paddle) was placed inbetween the beam and the CeBr₃ crystal to serve as reference beam monitor. An Arduino is used to monitor the high-voltage supply for the PMT and active divider electronics in terms of current, voltage and temperature. A Comet Systems® T7310 is used to monitor ambient temperature, humidity and pressure.

The published data consist of the raw signal waveforms acquired during ~450 measurements. Each measurement is stored in a separate folder, its name being the acquisition time start, and lasts between 3 and 20 seconds (16 GiB up to 100 GiB). The data format is little-endian binary. Each sample uses two bytes, being the 14 first bits the digitized signal in a 1.7 V_pp range, and the 15^th bit the (negated) logic status of the reference beam monitor (paddle). Samples are stored consecutively, without headers. Sample time separation is 0.4 ns (2.5 Gsps). The digitizer is phase-locked to the accelerator radiofrequency (RF), so that each 2500 stored samples correspond to 13 consecutive periods of 13 MHz.

The data can be directly opened using the open-source pulse visualization software (PulseSurfer) available in this link: https://igit.ific.uv.es/ferhue/pulse-surfer/, with ROOT as a dependency. One just needs to run:

root -l test_gui.cpp+(\"/path-to-folder/chA.bin\") 

and then set 192.307692307692307696 in the "Cycle" box. Use the slider in the bottom to navigate across different consecutive frames. To visualize the paddle counter (negated) logic status, change the "Mask" box from 3FFF to 4000. There is also a checkbox to activate the baseline subtraction.

In addition to the raw waveform data (chA.bin), each folder contains following metadata:

• log.root a ROOT file storing all the measurement and hardware settings as TObjString. It also contains the T7310 monitoring as a TTree ("pth")
• chA.root a ROOT file storing a TTree that benchmarks the readout speed of the DAQ for this channel
• zdt.log a text file storing the output printed by the DAQ software to terminal
• gui.png Screenshot of the DAQ window
• hv.txt a test file storing the monitoring of the high-voltage supply and electronics