A compact digital time differential perturbed angular correlation-spectrometer using field programmable gate arrays and various timestamp algorithms

Abstract

A user-friendly fully digital time differential perturbed angular correlation (TDPAC)-spectrometer with six detectors and fast digitizers using field programmable gate arrays (FPGA) is described and performance data are given. The new spectrometer has an online data analysis feature, a compact size, and a time resolution such as conventional analog spectrometers. Its calculation intensive part was implemented inside the digitizer. This gives the possibility to change parameters (energy windows, constant fraction trigger delay) and see their influence immediately in the γ-γ correlation diagrams. Tests were performed which showed that the time resolution using a (60)Co source with energy window set at 1.17 MeV and 1.33 MeV is 265 ps with LaBr(3)(Ce) scintillators and 254 ps with BaF(2) scintillators. A true constant fraction algorithm turned out to be slightly better than the constant fraction of amplitude method. The spectrometer performance was tested with a TDPAC measurement using a (44)Ti in rutile source and a positron lifetime measurement using (22)Na. The maximum possible data rate of the spectrometer is 1.1 × 10(6) γ quanta per detector and second.

Perturbed Angular Correlation of the stretched cascade in the decay of 180mHf using a digital spectrometer

“…We used a 6-detector spectrometer equipped with 38 mm ∅ × 38 mm LaBr 3 (Ce) scintillators mounted on XP2020URQ photomultipliers as described in [3]. The advantage of excellent energy resolution with such scintillators is clearly demonstrated in Fig.…”

“…However, a digital spectrometer can cope with multiple starts having the same time stamp. Here, we describe the first application of a recently developed digital spectrometer [3] to the stretched cascade in 180m Hf which renders this nuclear probe attractive for further applications, e.g. as Pu analog.…”

A digitizer based compact digital spectrometer for ion beam analysis using field programmable gate arrays and various energy algorithms

“…2 in Ref. 10). FPGA programming is combining these basic elements and the clock signal using an appropriate hardware description language (HDL) and synthesis tools.…”

The 68m Cu/ 68 Cu isotope as a new probe for hyperfine studies: The nuclear moments

“…The TDPAC set-up mounted online consisted of four LaBr 3 gamma detectors with good energy resolution (11.6% at 84.1 keV and 3.0% at 637 keV) and time resolution of 800 ps for the selected cascade. Data acquisition was performed with the digital and FPGA signal processing DIGIPAC setup [18][19][20]. The detectors were positioned in a plane perpendicular to the direction of the radioactive beam, each detector placed at ±90 • and 180 • with respect to the others, as shown in fig.…”