Mapping the Sensitive Volume of an Ion-Counting Nanodosimeter

We present two methods of independently mapping the dimensions of the sensitive volume in an ion-counting nanodosimeter. The first method is based on a calculational approach simulating the extraction of ions from the sensitive volume, and the second method on probing the sensitive volume with 250 MeV protons. Sensitive-volume maps obtained with both methods are compared and systematic errors inherent in both methods are quantified.Comment: 27 pages, 8 figures. Submitted to JINST, Jan. 16 200

Proton tracking for medical imaging and dosimetry

For many years, silicon micro-strip detectors have been successfully used as tracking detectors for particle and nuclear physics experiments. A new application of this technology is to the field of particle therapy, where radiotherapy is carried out by use of charged particles such as protons or carbon ions. Such a treatment has been shown to have advantages over standard x-ray radiotherapy and as a result of this, many new centres offering particle therapy are currently under construction—including two in the U.K.. The characteristics of a new silicon micro-strip detector based system for this application will be presented. The array uses specifically designed large area sensors in several stations in an x-u-v co-ordinate configuration suitable for very fast proton tracking with minimal ambiguities. The sensors will form a tracker capable of giving information on the path of high energy protons entering and exiting a patient. This will allow proton computed tomography (pCT) to aid the accurate delivery of treatment dose with tuned beam profile and energy. The tracker will also be capable of proton counting and position measurement at the higher fluences and full range of energies used during treatment allowing monitoring of the beam profile and total dose. Results and initial characterisation of sensors will be presented along with details of the proposed readout electronics. Radiation tests and studies with different electronics at the Clatterbridge Cancer Centre and the higher energy proton therapy facility of iThemba LABS in South Africa will also be shown

CMOS Active Pixel Sensors as energy-range detectors for proton Computed Tomography

Since the first proof of concept in the early 70s, a number of technologies has been proposed to perform proton CT (pCT), as a means of mapping tissue stopping power for accurate treatment planning in proton therapy. Previous prototypes of energy-range detectors for pCT have been mainly based on the use of scintillator-based calorimeters, to measure proton residual energy after passing through the patient. However, such an approach is limited by the need for only a single proton passing through the energy-range detector in a read-out cycle. A novel approach to this problem could be the use of pixelated detectors, where the independent read-out of each pixel allows to measure simultaneously the residual energy of a number of protons in the same read-out cycle, facilitating a faster and more efficient pCT scan. This paper investigates the suitability of CMOS Active Pixel Sensors (APSs) to track indi- vidual protons as they go through a number of CMOS layers, forming an energy-range telescope. Measurements performed at the iThemba Laboratories will be presented and analysed in terms of correlation, to confirm capability of proton tracking for CMOS APSs

Performance of a front-end prototype ASIC for the ATLAS High Granularity Timing Detector

This paper presents the design and characterisation of a front-end prototype ASIC for the ATLAS High Granularity Timing Detector, which is planned for the High-Luminosity phase of the LHC. This prototype, called ALTIROC1, consists of a 5$\times$5-pad matrix and contains the analog part of the single-channel readout (preamplifier, discriminator, two TDCs and SRAM). Two preamplifier architectures (transimpedance and voltage) were implemented and tested. The ASIC was characterised both alone and as a module when connected to a 5$\times$5-pad array of LGAD sensors. In calibration measurements, the ASIC operating alone was found to satisfy the technical requirements for the project, with similar performances for both preamplifier types. In particular, the jitter was found to be 15$\pm$1~ps (35$\pm$1~ps) for an injected charge of 10~fC (4~fC). A degradation in performance was observed when the ASIC was connected to the LGAD array. This is attributed to digital couplings at the entrance of the preamplifiers. When the ASIC is connected to the LGAD array, the lowest detectable charge increased from 1.5~fC to 3.4~fC. As a consequence, the jitter increased for an injected charge of 4~fC. Despite this increase, ALTIROC1 still satisfies the maximum jitter specification (below 65~ps) for the HGTD project. This coupling issue also affects the time over threshold measurements and the time-walk correction can only be performed with transimpedance preamplifiers. Beam test measurements with a pion beam at CERN were also undertaken to evaluate the performance of the module. The best time resolution obtained using only ALTIROC TDC data was 46.3$\pm$0.7~ps for a restricted time of arrival range where the coupling issue is minimized. The residual time-walk contribution is equal to 23~ps and is the dominant electronic noise contribution to the time resolution at 15~fC.Comment: 20 pages, 15 figures Second version submitted to JINST including minor changes applied to address journal's comment

Identification of Long-lived Charged Particles using Time-Of-Flight Systems at the Upgraded LHC detectors

We study the impact of precision timing detection systems on the LHC experiments’ long-lived particle search program during the HL-LHC era. We develop algorithms that allow us to reconstruct the mass of such charged particles and perform particle identification using the time-of-flight measurement. We investigate the reach for benchmark scenarios as a function of the timing resolution, and find sensitivity improvement of up to a factor of ten over searches that use ionization energy loss information, depending on the particle’s mass

Kriminalitet nasilja - serijska ubistva

Violence and murders represent the gravest forms of negation of the law. Following that fact, which is, according to the author, indisputable, the first part describes the terms which are most commonly used in defining the greatest number of murders performed by one perpetrator(serial killer, mass killer, spree killer). Besides that, in order to achieve insight into the abundance of terms which are used to designate certain murders, their short review is presented regarding the fact who the perpetrator is and who the victim of the murder is. In the second part of this work, consisting of two units, we point out the objective danger coming from the criminal acts of violence, and above all, from the murders, especially serial ones. The results of the research are given in the first part: who the most famous serial killers in Europe are, both in distant as well as in the recent past. The second part is a short analysis of the criminal acts of murder done in Republic of Serbia and Belgrade in the period between 2001 and 2005. In the end, as a conclusion of the work, as a prerequisitive for a successful prevention of criminal acts of violence, the definition of the following principle is given: Clearly demonstrated and legally defined cooperation of all segments of society based on partnership and sharing of responsibility is a basis for prevention of violence.Nasilje i ubistva predstavljaju najteži oblik negacije prava. Prateći tu, po autoru nespornu činjenicu, u prvom delu rada objašnjeni su termini koji se najčešće koriste za određenje većeg broja ubistava izvršenih od strane jednog učinioca (serijski ubica, masovni ubica). Pored toga, radi sticanja uvida u bogatstvo termina kojim se označavaju pojedina ubistva, dat je njihov kratak pregled u zavisnosti od toga ko je učinilac a ko žrtva. U drugom delu rada, koga čine dve celine, ukazano je na objektivnu ugroženost od krivičnih dela nasilja, a pre svega ubistava i to serijskih. Prvu od navedene dve celine čine rezultati istraživanja, ko su najpoznatije serijske ubice na području Evrope, kako u dalekoj prošlosti tako i u skorašnjoj istoriji. Druga celina predstavlja kratku analizu krivičnih dela ubistava izvršenih na području Republike Srbije i Beograda u periodu od 2001. do 2005. godine. Na kraju, u zaključcima rada, kao preduslov za uspešnu prevenciju krivičnih dela nasilja definisan je princip: Jasno ispoljena i zakonski definisana saradnja svih segmenata društva zasnovana na partnerstvu i podeli odgovornosti osnova je za prevenciju nasilja

Kriminalitet nasilja - serijska ubistva

Violence and murders represent the gravest forms of negation of the law. Following that fact, which is, according to the author, indisputable, the first part describes the terms which are most commonly used in defining the greatest number of murders performed by one perpetrator(serial killer, mass killer, spree killer). Besides that, in order to achieve insight into the abundance of terms which are used to designate certain murders, their short review is presented regarding the fact who the perpetrator is and who the victim of the murder is. In the second part of this work, consisting of two units, we point out the objective danger coming from the criminal acts of violence, and above all, from the murders, especially serial ones. The results of the research are given in the first part: who the most famous serial killers in Europe are, both in distant as well as in the recent past. The second part is a short analysis of the criminal acts of murder done in Republic of Serbia and Belgrade in the period between 2001 and 2005. In the end, as a conclusion of the work, as a prerequisitive for a successful prevention of criminal acts of violence, the definition of the following principle is given: Clearly demonstrated and legally defined cooperation of all segments of society based on partnership and sharing of responsibility is a basis for prevention of violence.Nasilje i ubistva predstavljaju najteži oblik negacije prava. Prateći tu, po autoru nespornu činjenicu, u prvom delu rada objašnjeni su termini koji se najčešće koriste za određenje većeg broja ubistava izvršenih od strane jednog učinioca (serijski ubica, masovni ubica). Pored toga, radi sticanja uvida u bogatstvo termina kojim se označavaju pojedina ubistva, dat je njihov kratak pregled u zavisnosti od toga ko je učinilac a ko žrtva. U drugom delu rada, koga čine dve celine, ukazano je na objektivnu ugroženost od krivičnih dela nasilja, a pre svega ubistava i to serijskih. Prvu od navedene dve celine čine rezultati istraživanja, ko su najpoznatije serijske ubice na području Evrope, kako u dalekoj prošlosti tako i u skorašnjoj istoriji. Druga celina predstavlja kratku analizu krivičnih dela ubistava izvršenih na području Republike Srbije i Beograda u periodu od 2001. do 2005. godine. Na kraju, u zaključcima rada, kao preduslov za uspešnu prevenciju krivičnih dela nasilja definisan je princip: Jasno ispoljena i zakonski definisana saradnja svih segmenata društva zasnovana na partnerstvu i podeli odgovornosti osnova je za prevenciju nasilja