Requirements on quantum superpositions of macro-objects for sensing neutrinos

We examine a macroscopic system in a quantum superposition of two spatially separated localized states as a detector for a stream of weakly interacting relativistic particles. We do this using the explicit example of neutrinos with MeV-scale energy scattering from a solid object via neutral-current neutrino-nucleus scattering. Presuming the (anti)neutrino source to be a nuclear fission reactor, we utilize the estimated flux and coherent elastic neutrino-nucleus cross section to constrain the spatial separation Δx and describe the temporal evolution of the sensing system. Particularly, we find that a potentially measurable relative phase between quantum superposed components is obtained for a single gram scale mass placed in a superposition of spatial components separated by 10−14m under sufficient cooling and background suppression

QuARC: A Quality Assurance Range Calorimeter for Proton Therapy

Proton therapy offers highly localised dose distribution and better healthy tissue sparing over conventional radiotherapy. Crucial in optimising patient safety is the proton range: this is the largest source of uncertainty in proton therapy and prevents full advantage being taken of the superior dose conformality. In the clinic, daily Quality Assurance (QA) is performed each morning before patient treatment, including verification of the proton range in water (a proxy for human tissue) for specific beam energies. This process however, often compromises between speed and accuracy. Recently, there has been increased interest in FLASH: a high dose rate form of radiotherapy offering even greater healthy tissue sparing. However, standard detectors used in QA become unusable at FLASH dose rates. The Quality Assurance Range Calorimeter (QuARC) is currently under development at UCL with our industrial partners Cosylab to provide fast, accurate, water-equivalent proton range measurements for daily QA, with the capability to operate at FLASH dose rates. Based on plastic scintillator developed for the SuperNEMO experiment, the detector is a series of optically isolated scintillator sheets that sample the proton energy deposition along its path. Light from each sheet is measured by a series of photodiodes: this light output is proportional to the deposited energy. An analytical depth-light model is used to fit the data and measure the proton range to sub-mm precision. Two preliminary beam tests at UCLH with proton pencil beams between 70-110 MeV found that the QuARC is able to consistently recover proton ranges with good accuracy, even at low light levels. Fast curve fitting enables stable real-time range reconstruction at 40 Hz, as protons are delivered to the detector. Due to large dynamic range, the detector can be scaled up to FLASH dose rates. Further measurements are required to fully characterise detector performance and light output with FLASH

Proof of principle detector for fast patient quality assurance

Standard clinical practice in particle therapy is to verify the treatment plan for each patient before the plan is delivered. This patient specific QA process normally involves repeated delivery of the treatment plan to a water or water equivalent volume, with changes to the position of a dosimeter or dosimetric array in order to measure the volumetric dose distribution. Due to the repeated delivery of each field, patient QA can be extremely time consuming. An ideal patient QA system would allow measurements at the speed of treatment delivery ie. within a few minutes. We present measurements with a simple proof-of-concept system for fast patient QA. The system is essentially a stripped-down proton CT detector, utilising a single tracking detector developed for the PRaVDA proton CT detector coupled to a single scintillating calorimeter module adapted from the SuperNEMO high energy physics experiment. The calorimeter consists of a plastic scintillator, providing the water-equivalent medium into which the beam is delivered. By measuring the position of each particle as it enters the calorimeter it is possible to reconstruct the dose deposition of individual particles and thereby reconstruct the 3D volumetric dose deposition. Results are presented from experiments with protons at the Birmingham University 36MeV cyclotron showing volumetric dose reconstruction at proton rates well below clinical fluences. A method for scaling this system up to a full clinical patient QA system is also described

Spread-out Bragg peak measurements using a compact quality assurance range calorimeter at the Clatterbridge cancer centre

Objective. The superior dose conformity provided by proton therapy relative to conventional x-ray radiotherapy necessitates more rigorous quality assurance (QA) procedures to ensure optimal patient safety. Practically however, time-constraints prevent comprehensive measurements to be made of the proton range in water: a key parameter in ensuring accurate treatment delivery. / Approach. A novel scintillator-based device for fast, accurate water-equivalent proton range QA measurements for ocular proton therapy is presented. Experiments were conducted using a compact detector prototype, the quality assurance range calorimeter (QuARC), at the Clatterbridge cancer centre (CCC) in Wirral, UK for the measurement of pristine and spread-out Bragg peaks (SOBPs). The QuARC uses a series of 14 optically-isolated 100 × 100 × 2.85 mm polystyrene scintillator sheets, read out by a series of photodiodes. The detector system is housed in a custom 3D-printed enclosure mounted directly to the nozzle and a numerical model was used to fit measured depth-light curves and correct for scintillator light quenching. / Main results. Measurements of the pristine 60 MeV proton Bragg curve found the QuARC able to measure proton ranges accurate to 0.2 mm and reduced QA measurement times from several minutes down to a few seconds. A new framework of the quenching model was deployed to successfully fit depth-light curves of SOBPs with similar range accuracy. / Significance. The speed, range accuracy and simplicity of the QuARC make the device a promising candidate for ocular proton range QA. Further work to investigate the performance of SOBP fitting at higher energies/greater depths is warranted

A High Pressure Time Projection Chamber with Optical Readout

Measurements of proton-nucleus scattering and high resolution neutrino-nucleus interaction imaging are key to reduce neutrino oscillation systematic uncertainties in future experiments. A High Pressure Time Projection Chamber (HPTPC) prototype has been constructed and operated at Royal Holloway University of London and CERN as a first step in the development of a HPTPC capable of performing these measurements as part of a future long-baseline neutrino oscillation experiment such as the Deep Underground Neutrino Experiment. In this paper we describe the design and operation of the prototype HPTPC with an argon based gas mixture. We report on the successful hybrid charge and optical readout, using four CCD cameras, of signals from Am-241 sources.Comment: 40 pages, 24 figure

Two-Neutrino Double-Beta Decay

Two-neutrino double-β decay is a radioactive process with the longest lifetime ever observed. It has been a subject of experimental research for more than 60 years and remains an important topic in modern nuclear and particle physics. This review examines the process in detail, covers its theoretical and experimental aspects, and describes the results obtained so far and future challenges. </jats:p

Uniform-tangential approximation by analytical functions, applications

The study deals with classes of functions uniformly approximated in closed subsets of the region by analytical in the region functions. The work is aimed at studying the properties of classes of uniformly approximated functions, the relation of the uniqueness problem with the problems on a possibility of a tangential approximation, application of the theorems on approximation. The known Wolf method in modified. The Gonchar hypothesis is confirmed. New generalizations of the maximum principle and Mittag-Leffler and Weierstrass theorems are received. The results can be used in the theory of approximation and the theory of distribution of values of analytical functions and their applicationsAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio