Fig 2 - uploaded by Jens Röder
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Raw data as an array of segments. Each segment having 400 data points. The width of the data points depends of the defined sampling rate, which is here at 1 GS/s. One segment contains the waveform of one event
Source publication
![Table 2 Fit-data of Fe-foil Fraction [%] ω L [MHz] δ [MHz]](profile/Jens-Roeder/publication/226383698/figure/tbl1/AS:393710480183299@1470879301725/Fit-data-of-Fe-foil-Fraction-o-L-MHz-d-MHz_Q320.jpg)
In conventional perturbed angular correlation (PAC)-spectroscopy huge amounts of events are processed by fast electronics.
Modern digital signal processing devices and the improvement in the computer technology in recent years allow today digital
PAC-spectrometer setups capable to perform software-based data processing with all the benefits of stor...
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Yttria-stabilized cubic zirconia powders and coatings produced by the sol-gel method have been investigated by Perturbed Angular Correlation Spectroscopy (PAC). Results indicate that the metastable cubic phase is retained during heating and cooling cycles. The hyperfine interaction that describes this cubic phase, once crystallized, exhibits two co...
The jump frequency of Cd tracer atoms was measured as a function of temperature in seven rare-earth tri-indide intermetallic compounds having the L1 2, or Cu 3Au, structure. The frequency, proportional to the diffusivity, was detected by relaxation of nuclear quadrupole interaction at Cd nuclei caused by reorientation of the electric field gradient...
Electric field gradients (EFG) at the metal center were studied in seven chloroindium porphyrin complexes and in chloroindium phthalocyanine by the technique of perturbed angular correlation of gamma rays. These complexes were synthesized with the probe nucleus /sup 111/In for use in polycrystalline and solution sources. The magnitudes of the EFGs...
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Perturbed angular correlation of gamma rays (PAC) was applied to measure concentrations of point defects in quenched and milled
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Citations
... A month later the transmission was confirmed with a new set of voltages and with stable, laser-ionized Cu ions. Then the first short-lived radioactive beam of 68m Cu (T 1/2 = 3.75 min) was taken to the sample holder mounted inside a quartz finger collection chamber set up at the central station, shown in Fig. 4. Using the PAC technique with Field Programmable Gate Arrays (FPGA) [17] and List mode digital set- ups [18], and four high resolution LaBr 3 gamma detectors in a plane array perpendicular to the beam direction, the appropriate cascade (intermediate state of 7.84 ns half-life, 84 keV and I = 2 + ) could be resolved leading to the first ever on-line (and off-line) PAC experiment performed on a Cu isotope. Several PAC time spectra were obtained by implantation into Ni and Co foils using continuous measurement, aimed at probing the magnetic interactions . ...
The VITO (Versatile Ion-polarized Techniques Online) project is a new experimental setup at the ISOLDE facility at CERN. VITO is a dedicated beam line for producing laser-induced spin-polarized beams of both, atoms and ions, and it has been commissioned in response to the continuously growing demand for the use of spin-polarized beams. The new VITO beam line is a modification of the formerly existing ultra-high vacuum beam line, connecting ASPIC (Apparatus for Surface Physics and Interfaces at CERN), and it has been under construction since the beginning of 2014. Once fully commissioned, VITO will open up numerous possibilities for carrying out multidisciplinary experiments in the areas of nuclear and solid state physics, fundamental interaction physics and biophysics. In its final stage the VITO beam line will provide three fully independent experimental stations: UHV chamber for material science applications, a β-asymmetry station where highly-polarized ions will be available, and a central open-end station suitable for travelling experiments. The VITO beam line will operate in two different modes providing either beams of spin-polarized atoms or ions, or non-polarized ion beams to all three end stations operating from 10−10 mbar to 50 mbar. Recent experimental campaigns with stable and radioactive beams have allowed for testing VITO’s constituent parts and have demonstrated 96% of ion beam transmission to the collection chamber installed on the central station. The first experimental results obtained with on-line Perturbed Angular Correlation (PAC) spectroscopy using 68mCu ion-beams will be briefly discussed.
... PAC measurements were performed at room temperature (RT) using two Digital Time Differential PAC machines (DTDPAC) [38,39] with four BaF 2 detectors resulting in 12 single spectra of 90° and 180° per measurement. All the detected c-rays were saved as time and energy values on the DTDPAC machine's hard disks. ...
Nano-crystalline ZnO has been studied with perturbed angular correlation using 111mCd, implanted at ISOLDE/CERN and X-ray diffraction using Rietveld analysis. The data show a gradual increase in the crystal size and stress for a sample annealed at 600 °C, and reaching nearly properties of standard ZnO with tempering at 1000 °C. The perturbed angular correlation data show a broad frequency distribution at low annealing temperatures and small particle sizes, whereas at high annealing temperature and larger crystal sizes, results similar to bulk ZnO have been obtained. The ZnO nano-crystalline samples were initially prepared through a wet chemical route, have been examined by Fourier Transform Infrared Spectroscopy (FT-IR) and chemical purity has been confirmed with Energy Dispersive X-ray (EDAX) analysis as well as Transmission Electron Microscopy (TEM).
In order to obtain quantitative information about the changes of the EFG in closed-shell metal-organic molecules by the interactions with an inert matrix, two cases, dimethylmercury and dimethylcadmium, were measured using 199mHg and 111mCd PAC, respectively, in frozen diethyl ether and tetrahydrofuran. With the knowledge of high-accuracy nuclear quadrupole moments and available precision EFG values from quantum chemistry CCSD-T calculations the expected NQI frequencies of the free molecules are available and can be compared to the ones measured in the frozen solutions.
We present a simplified digital time differential perturbed γ − γ angular correlation (TDPAC) spectrometer that demonstrates that such instruments can be built using primarily commercial components and with relatively modest coding effort. The system handles data rates of 70 kcps/detector with a timing resolution of better than 500 ps, and has been used with both 111In and 181Hf.
A user-friendly fully digital TDPAC-spectrometer with six detectors and fast digitizers using Field Programmable Gate Arrays
is described and performance data are given.
KeywordsUser-friendly–Digital TDPAC-spectrometer–Field programmable gate arrays
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.
A new digital time differential perturbed angular correlation spectrometer, designed to measure the energy of and coincidence time between correlated detector signals, here correlated gamma photons, is presented. The system overcomes limitations of earlier digital approaches and features improved performance and handling. By consequently separating the data recording and evaluation, it permits the simultaneous measurement of decays with several gamma-ray cascades at once and avoids the necessity of premeasurement configuration. Tests showed that the spectrometer reaches a time resolution of 460 ps [using a (60)Co sample and Lu(1.8)Y(0.2)SiO(5):Ce (LYSO) scintillators, otherwise better than 100 ps], an energy resolution that is equivalent to the limit of the used scintillation material, and a processing capability of more than 200,000 gamma quanta per detector and second. Other possible applications of the presented methods include nuclear spectroscopy, positron emission tomography, time of flight studies, lidar, and radar.
