P. Žugec

Pulse processing routines for neutron time-of-flight data

A pulse shape analysis framework is described, which was developed for n_TOF-Phase3, the third phase in the operation of the n_TOF facility at CERN. The most notable feature of this new framework is the adoption of generic pulse shape analysis routines, characterized by a minimal number of explicit assumptions about the nature of pulses. The aim of these routines is to be applicable to a wide variety of detectors, thus facilitating the introduction of the new detectors or types of detectors into the analysis framework. The operational details of the routines are suited to the specific requirements of particular detectors by adjusting the set of external input parameters. Pulse recognition, baseline calculation and the pulse shape fitting procedure are described. Special emphasis is put on their computational efficiency, since the most basic implementations of these conceptually simple methods are often computationally inefficient.

A simple setup for cosmic muon lifetime measurements

Elementary particle physics is a fascinating field of modern physics investigating the basic constituents of matter and their interactions. In the experiments large accelerators and very sophisticated detector systems are usually used. However, it is desirable to have simple experiments for undergraduate and even secondary school courses which can demonstrate complex investigations in this field. We have constructed a simple setup for the measurement of the lifetime of cosmic muons based on a single scintillation detector. Expensive and complicated professional particle physics equipment for the signal processing, which mainly prevented the realization of this experiment by non-experts, is replaced by simple, inexpensive and commercially available electronic components. With our setup we register time stamps of the events detected in the scintillation detector and from this data we determine the muon lifetime. Also, Python software package has been developed for data analysis and presentation of the results.

A direct method for unfolding the resolution function from measurements of neutron induced reactions

Abstract The paper explores the numerical stability and the computational efficiency of a direct method for unfolding the resolution function from the measurements of the neutron induced reactions. A detailed resolution function formalism is laid out, followed by an overview of challenges present in a practical implementation of the method. A special matrix storage scheme is developed in order to facilitate both the memory management of the resolution function matrix, and to increase the computational efficiency of the matrix multiplication and decomposition procedures. Due to its admirable computational properties, a Cholesky decomposition is at the heart of the unfolding procedure. With the smallest but necessary modification of the matrix to be decomposed, the method is successfully applied to system of 1 0 5 × 1 0 5 . However, the amplification of the uncertainties during the direct inversion procedures limits the applicability of the method to high-precision measurements of neutron induced reactions.

An improved method for estimating the neutron background in measurements of neutron capture reactions

The relation between the neutron background in neutron capture measurements and the neutron sensitivity related to the experimental setup is examined. It is pointed out that a proper estimate of the neutron background may only be obtained by means of dedicated simulations taking into account the full framework of the neutron-induced reactions and their complete temporal evolution. No other presently available method seems to provide reliable results, in particular under the capture resonances. An improved neutron background estimation technique is proposed, the main improvement regarding the treatment of the neutron sensitivity, taking into account the temporal evolution of the neutron-induced reactions. The technique is complemented by an advanced data analysis procedure based on relativistic kinematics of neutron scattering. The analysis procedure allows for the calculation of the neutron background in capture measurements, without requiring the time-consuming simulations to be adapted to each particular sample. A suggestion is made on how to improve the neutron background estimates if neutron background simulations are not available.

A coincidental timing model for the scintillating fibers

A model describing the coincidental timing of scintillating fibers is developed. Fiber geometry, the rate of scintillation decay together with the mean number, spatial dispersion and attenuation of emitted photons is considered. For a specific selection of probability distributions and parameters involved, the entire coincidental timing distributions, corresponding FWHM values and the photon detection efficiencies are extracted. The significance of the number of photons from the scintillation process is specially emphasized. Additionally, the model is extended to include a triggering feature, experimentally realized by coupling fibers to any photon resolving device. Finally, the measurements of a coincidental timing distribution were performed, with an excellent agreement found between the experimental and predicted theoretical results.