Time Of Flight System Research Articles

Hypervelocity impact induced light flash experiments on single and dual layer Kapton targets to develop a time of flight space dust and debris detector

The impact flash from hypervelocity impact on thin (12.5 µm) Kapton film was observed. The projectile sizes ranged from 0.1 to 1 mm, with speeds from 2 to 5 km s−1 and penetrated the Kapton intact, leaving holes the same size as the projectile (to within measurement errors). The flash intensity (normalised to impactor mass) scaled with impact speed to the power 5.5. However, the data also suggest that at constant speed the intensity scales with the area of the hole in the Kapton and not the projectile mass (i.e. with some property of the target and not as a function of the projectile energy or momentum). Using two layers of Kapton, it was possible to construct a Time of Flight (TOF) system, which used the time of the onset of the flash in each layer to produce flight speeds accurate to within typically 1%. When compared to the projectile speed pre-impact, there was no indication of projectile deceleration during passage through the Kapton film. In addition, when PVDF acoustic sensors were placed on the Kapton film, they exhibited an electromagnetic “pick-up” signal from the impact of projectile on the Kapton, confirming suspicions of signal interference from past work with acoustic sensors. The ability of the light flash to provide accurate impact timing signals suggests the TOF system would be suitable for use as a cosmic dust or debris impact detector in space (e.g. Low Earth Orbit).

Design and performance testing of a T0 detector for the CSR External-target Experiment

The Cooling Storage Ring External-target Experiment at the Heavy Ion Research Facility in Lanzhou, China, is a multi-purpose nuclear physics experimental device to operate in the Giga electron-volt (GeV) energy range. The time-of-flight (TOF) system is critical for identifying charged particles in the GeV energy range. In the Experiment spectrometer, the TOF system consists of three parts: T0, internal TOF, and external TOF. The T0 detector provides a high-precision start time for the TOF system by measuring the crossing time of the heavy ion beam. This study details the design, performance simulation, and performance testing of the T0 detector. The simulation results and heavy-ion beam test show that the T0 detector prototype has an excellent time resolution, which is better than 30 ps, and fulfills the requirements of the CEE.

A conceptual design of TOF based on MRPC technology for the future electron–positron Higgs factory

Future electron–positron Higgs factories could provide excellent opportunities to examine the Standard Model and search for new physics with much higher precision than the LHC. A precise particle identification is crucial for the physics program at these future colliders and can be achieved via precise time-of-flight (TOF) measurements of the final state particles. In this paper, we propose a conceptual design of TOF system based on the multigap resistive plate chamber (MRPC) technology for future electron–positron Higgs factories. This TOF system will be characterized by a time resolution of < 35 ps, a total active area of 77 m2, and a construction budget of the order of 5 million USD.

Development of a sealed MRPC with mylar spacers for high luminosity TOF systems

The high luminosity Time-of-Flight (TOF) systems call for timing detectors with both good time resolution and adequate rate capability, which have been fulfilled by the Multigap Resistive Plate Chamber (MRPC) assembled with low-resistive glass electrodes. However, recent tests and operations with high rate MRPCs have given evidences to the luminosity effects, such as the dark current rise and related higher noise rate, which may vitiate the stability in experimental operations. This work discusses the results from observations and tests, and infer the fishline spacers as a source of dark current and noise problems. Then, a sealed MRPC with mylar spacers is proposed, developed and tested. The prototype showed good luminosity tolerance during the X-ray test, and its performances of 95% efficiency and 80 ps time resolution have been validated in cosmic tests.

Study of the central exclusive production of π+π−, K+K−, and pp̄ pairs in proton-proton collisions at s = 510 GeV with the STAR detector at RHIC

We report on the measurement of the central exclusive production process [Formula: see text] in proton-proton collisions at [Formula: see text] GeV with the STAR detector at RHIC. At this energy, the process is dominated by a double Pomeron exchange mechanism. The tracks of the centrally produced system [Formula: see text] were reconstructed in the central detector of STAR, the time projection chamber and the time of flight systems. Particles were identified using the ionization energy loss and the time of flight method. The diffractively scattered protons, moving intact inside the RHIC beam pipe after the collision, were measured in the Roman Pots system allowing full control of the interaction’s kinematics and verification of its exclusivity. Preliminary results on the invariant mass distributions of centrally produced [Formula: see text], [Formula: see text], and [Formula: see text] pairs measured within the STAR acceptance are presented.

The Upgrade of the T2K ND280 Detector

The Tokai to Kamiokande (T2K) experiment is a long-baseline neutrino experiment taking data since 2010. The neutrino beam is detected on two sites, the near detector complex close to the neutrino production point, and Super-Kamiokande in a distance of 300 km. The ND280 detector is one of the near detectors and has the purpose to characterize the beam before oscillation as also the measurement of interaction cross sections. Both is crucial to reduce the systematic uncertainties. To improve the latter further, the T2K collaboration decided in 2016 an upgrade of ND280 which includes the installation of a novel scintillator tracker, two time projection chambers and a time of flight system. This upgrade, in combination of an increase of the neutrino beam power from currently 500 kW to 1.3 MW, will roughly increase the statistics by a factor 4 and reduce the systematic uncertainties from 6% to 4%. The new subdetectors are currently being assembled and will be installed in 2022. The upgraded ND280 will also serve as near detector of the next generation long-baseline neutrino oscillation experiment Hyper-Kamiokande.

Fast lightweight framework for time-of-flight super-resolution based on block compressed sensing.

Compressive time-of-flight (ToF) imaging for super-resolution (SR) has tremendous development potential owing to its cost-effectiveness and simplicity. However, existing compressive ToF methods are difficult to apply in practical situations because of their low efficiency and high data storage requirements. In this paper, we propose a fast and lightweight compressive ToF framework for SR. The block compressed sensing method, which shows distinct characteristics of high efficiency and low implementation cost, is introduced into the SR image acquisition and data transmission processes. Based on this framework, we establish a prototype system and verify it experimentally. Compared with existing compressive ToF systems, both the reconstruction time and data storage requirements are significantly decreased. We believe that this study provides a development direction for compressive ToF imaging and effective guidance for researchers realizing highly efficient and lightweight SR image reconstruction.

Beam test results of the MRPC prototype for the new NA61/SHINE ToF system

A new Time-of-Flight (ToF) detector of the NA61/SHINE hadron spectrometer at CERN SPS based on Multigap Resistive Plate Chambers (MRPCs) technology is offered as a substitution of the scintillation ToF detector developed in 1990s. In 2019–2020, a prototype module of the new ToF system was tested on the 280 MeV/c positron beam to determine its characteristics. The analogue front-end electronics and DRS4-based waveform digitizer were used as a readout chain. This article presents the results of the MRPC test with analogue readout obtained in 2019–2020.

Evaluation of Reconstruction Algorithms to Validate the NEMA Phantom Results in Clinical Scenario - A Comparative Study Using Time-of-Flight versus Non-Time-of-Flight Positron Emission Tomography Imaging.

Objectives:The objective is to standardize the reconstruction parameters for the time-of-flight (TOF) versus non-TOF positron-emission tomography/computed tomography (PET/CT) imaging data and validation of the same in a clinical setting.Methods:The four spheres (10.0/13.0/17.0/22.0 mm) of the PET phantom (NEMA IQ Nu 2-2001) were filled with four times higher activity of [18F]-NaF than the background (5.3kBq/mL). Imaging (image matrix – 128 × 128 × 47, 2 min, 3D model) was done using two different (TOF/non-TOF) PET scanners. Phantom data were reconstructed in TOF and non-TOF modes for lutetium–yttrium oxyorthosilicate and non-TOF mode for bismuth germanate-based PET scanners. The reconstructed data (by varying iteration and subsets) that provided the best image contrast and signal-to-noise ratio (SNR) were evaluated. The whole-body [18F]-fludeoxyglucose (FDG) PET/CT scans (7–8 frames; 2.0 min/frame) in 16 lymphoma patients were acquired at 60 min after injecting the radioactivity (370.0–444.0 MBq of [18F]-FDG. The clinical PET/CT data were reconstructed using phantom-derived reconstruction parameters and evaluated for image contrast and SNR of the detected lesions.Results:TOF reconstruction at second iteration provided significantly (P ≤ 0.02) higher SNR (20.7) and contrast (contrast recovery coefficient/background variability = 3.21) for the smallest hot lesions (10.0 mm) in the phantom than the non-TOF system. Similarly, in patient data analysis for the selected FDG avid lesions, the SNR values were significantly (P = 0.02) higher (13.3 ± 6.49) in TOF than (11 ± 6.48) in non-TOF system. Further, the small (≤10.0 mm) lesions were seen more distinctly in TOF system.Conclusion:It is thus observed that TOF reconstruction converged faster than the non-TOF, and the applicability of the same may impact the image quality and interpretation in the clinical PET data. The validation of the phantom-based experimental reconstruction parameters to clinical PET imaging data is highly warranted.

Phantom Validation of a Conservation of Activity-Based Partial Volume Correction Method for Arterial Input Function in Dynamic PET Imaging

Dynamic PET (dPET) imaging can be utilized to perform kinetic modelling of various physiologic processes, which are exploited by the constantly expanding range of targeted radiopharmaceuticals. To date, dPET remains primarily in the research realm due to a number of technical challenges, not least of which is addressing partial volume effects (PVE) in the input function. We propose a series of equations for the correction of PVE in the input function and present the results of a validation study, based on a purpose built phantom. 18F-dPET experiments were performed using the phantom on a set of flow tubes representing large arteries, such as the aorta (1” 2.54 cm ID), down to smaller vessels, such as the iliac arteries and veins (1/4” 0.635 cm ID). When applied to the dPET experimental images, the PVE correction equations were able to successfully correct the image-derived input functions by as much as 59 ± 35% in the presence of background, which resulted in image-derived area under the curve (AUC) values within 8 ± 9% of ground truth AUC. The peak heights were similarly well corrected to within 9 ± 10% of the scaled DCE-CT curves. The same equations were then successfully applied to correct patient input functions in the aorta and internal iliac artery/vein. These straightforward algorithms can be applied to dPET images from any PET-CT scanner to restore the input function back to a more clinically representative value, without the need for high-end Time of Flight systems or Point Spread Function correction algorithms.

Two-dimensional multi-layered SiN-on-SOI optical phased array with wide-scanning and long-distance ranging.

Silicon based optoelectronic integrated optical phased array is attractive owing to large-dense integration, large scanning range and CMOS compatibility. In this paper, we design and fabricate a SiN-on-SOI two-dimensional optical phased array chip. We demonstrate a two-dimensional scanning range of 96°×14.4° and 690 mW peak power of the main lobe. Additionally, we set up the time of flight (ToF) and frequency-modulated continuous-wave (FMCW) ranging systems by using this optical phased array chip, and achieve the objects detection at the range of 20 m in the ToF system and 109 m in the FMCW system, respectively.

Size-Exclusion Particle Separation Driven by Micro-Flows in a Quasi-Spherical Droplet: Modelling and Experimental Results.

Aqueous solution droplets are supported quasi contact-free by superhydrophobic surfaces. The convective flow in evaporating droplets allows the manipulation and control of biological molecules in solution. In previous works, super-hydrophobic drops on nano-patterned substrates have been used to analyze otherwise undetectable species in extremely low concentration ranges. Here, we used particle image velocimetry (PIV) for studying the flow field in water droplets containing polystyrene particles on a pillared silicon super-hydrophobic chip. The particles describe vortex-like motions around the droplet center as long as the evaporating droplet maintains a spherical shape. Simulations by a Finite Element Method (FEM) suggest that the recirculating flow is due to the temperature gradient along the droplet rim, generating a shear stress. Notably, the characteristics of the internal flow can be modulated by varying the intensity of the temperature gradient along the drop. We then used the flow-field determined by experiments and an approximate form of the Langevin equation to examine how particles are transported in the drop as a function of particle size. We found that larger particles with an average size of are preferentially transported toward the center of the substrate, differently from smaller particles with a 10-fold lower size that are distributed more uniformly in the drop. Results suggest that solutions of spherical particles on a super-hydrophobic chip can be used to separate soft matter and biological molecules based on their size, similarly to the working principle of a time-of-flight (ToF) mass analyzer, except that the separation takes place in a micro-sphere, with less space, less time, and less solution required for the separation compared to conventional ToF systems.

Detector control system for the CBM-TOF

A high-performance time-of-flight (TOF) MRPC wall is being built for the CBM experiment at FAIR for charged hadron identification. The detector control system for the TOF system will be based on EPICS. All components like power supplies for low and high voltages, power distribution boxes, gas control and front-end electronics (FEE) are controlled and monitored. In a test, called mini-CBM, all these functionalities are implemented and tested. For monitoring the detector environment and the status of the front-end electronics, a slow control application is implemented based on IPbus, which is an FPGA-based slow control bus used for the TOF data acquisition system. In addition to the functions of control and monitoring, exception handling and data archiving services are implemented as well. This system has been fully verified in beam tests in 2019 at GSI.

Performance Evaluation of the TOF-Wall Detector of the FOOT Experiment

The correct quantification of the dose released in charged particle therapy treatments requires the knowledge of the double differential fragmentation cross section of particles composing both the beam and the target. The FragmentatiOn Of Target (FOOT) experiment aims at measuring these cross sections for ions of interest for charged particle therapy applications. This article describes the performance of the time-of-flight (TOF)-wall detector of the experiment. The detector is composed of two layers of 44 cm ×2 cm ×3 mm plastic scintillator bars (20 for each layer), arranged orthogonally and read-out by silicon photomultipliers. The detector is designed to identify the charge of fragments ranging from protons to oxygen ions, with a maximum energy of 700 MeV/u, by measuring the energy released in the scintillators and the TOF with respect to a start counter. In this study, the detector was scanned with carbon ions of energy between 115 and 400 MeV/u and with a 60-MeV proton beam. The measurements show an energy resolution (σ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</sub> /μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</sub> ) between 6% and 4% and a contribution of the detector to the TOF system time resolution between 25 and 20 ps (standard deviation) for carbon ions and between 100 and 80 ps for protons.

Three-dimensional Fourier-based reprojection analytic reconstruction from histoprojections for high-resolution time-of-flight positron emission tomography scanners

Purpose: In spite of the general acceptance of iterative reconstruction for clinical use, analytic algorithms provide an important alternative tool due to their linearity, unbiased performance, and predictability for quantitative imaging and quality control studies. On modern time-of-flight (TOF) positron emission tomography scanners with excellent timing resolution, substantial angular compression of (histoprojection) data is possible without loss of resolution, but this also brings challenges for analytical algorithms. We propose TOF and non-TOF Fourier-based analytic approaches that appropriately handle the data sparsity on modern TOF systems. Approach: The proposed TOF algorithm (3D-DIFTOF-direct inversion Fourier transform for TOF) works directly on histoprojection data. The proposed Fourier-based approaches for histoprojection data are further extended to include non-TOF reconstruction (TOF-binned 3D-DIFT), which is particularly useful in time calibration procedures due to its insensitivity to time calibration errors. TOF information is used here to extend available histoprojection data to a larger number of views, essential for artifact-free non-TOF reconstruction. The proposed algorithms are compared with standard analytic techniques on Siemens scanners-space-based confidence-weighted TOF FBP and non-TOF DIFT. Results: 3D-DIFTOF reconstruction demonstrates both improved NEMA-based resolution and contrast versus background variability trade-offs. Similarly, the TOF-binned 3D-DIFT approach shows improved contrast-noise trade-offs over the standard non-TOF approach and is well suited for timing calibration. Conclusions: Our results demonstrate that the proposed 3D-DIFTOF technique provides an improved and more faithful characterization of image resolution compared with standard space-based analytic reconstructions. The proposed tools also provide accurate translation of sparse TOF data available on clinical scanners to upsampled data for non-TOF algorithms.

Construction of a Time-Of-Flight System for Beams Charge-Bred by using the Electron Beam Ion Source

A time-of-flight (TOF) system adopting single reflection has been constructed to identify the charge states of ions charge-bed by using the electron beam ion source (EBIS). The reflection allows for time focusing of the system in a compact manner. The EBIS under construction will enhance the charge states of rare isotopes produced by isotope separation on line (ISOL) so as to utilize the superconducting post linear accelerator efficiently. The TOF system consists of an ion-gate, reflection electrodes and multi-channel plates (MCP) detector. The maximum voltage on ions is 20 kV, and the beam optics design was performed using SIMION. In the front end of the TOF an ion gate is located to produce a single 5- to 10-ns pulse operating at a maximum voltage of ±1 kV. The circuit of the fast switching system, which converts -1 kV to 1 kV in a few ns, was simulated for an equivalent circuit of the gate by using LTspice. The TOF system is being fabricated and will be connected to a Cs ion source for initial beam tests with Cs1+ mixed with background ions.

Timing performances of a Time-Of-Flight detection system for the FRACAS large acceptance mass spectrometer

In this work, we report on the timing performances of the Time-Of-Flight (TOF) apparatus of the FRACAS large acceptance mass spectrometer designed to measure the fragmentation cross sections of a 12C beam in hadrontherapy. The TOF system is composed of a Parallel Plate Avalanche Counter and scintillating detectors to create so-called ΔE—TOF maps used in the fragment charge identification process. From tests with an alpha source and a 12C beam experiment, we measured a coincidence resolving time for the apparatus below 300 ps. Those results should lead in the final design to the identification of all the fragments produced by the interaction of 12C ions with thin targets for energies up to 400 MeV/nucleon.

Construction and test of an ion-gate with high-voltage switch system for single-reflection time of flight measurement

An ion gate and its high-voltage pulse switch system are constructed to produce a few nanosecond pulse beam so that the beam can be used for the time of flight (TOF) measurement. The maximum gating voltages are set to be ±1 kV to deflect away ion beams of intermediate heavy nuclei such as 133Cs when the gate is closed. The ion gate was designed by calculating deflection angles analytically and was checked numerically, which were in agreement. On the other hand, the switch system uses a Behlke switch, solid-state high voltage device, for pulse gating and its circuit was designed utilizing an equivalent circuit of the gate. Simulation by LTspice showed that a 10 ns pulse with a peak voltage of 2 kV can be produced if the capacitance of the gate is less than 50 nF. The ion gate was first tested inside the TOF system to ensure that a Cs1+ beam can be turned on and off in terms of beam arriving at a Faraday cup. The switch was then tested in connection with the gate, and we found that the pulse can be produced and its peak can be controlled by adjusting the capacitance of connection cables so far as its width is kept.

Novel low resistivity glass: MRPC detectors for ultra high rate applications

Multigap Resistive Plate Chambers (MRPCs) are often used as time-of-flight (TOF) detectors for high-energy physics and nuclear experiments thanks to their excellent time accuracy. For the Compressed Baryonic Matter (CBM) TOF system, MRPCs are required to work at particle fluxes on the order of 1–10kHz/cm2 for the outer region and 10–25kHz/cm2 for the central region. Better time resolution will allow particle identification with TOF techniques to be performed at higher momenta. From our previous studies, a time resolution of 25ps has been obtained with a 20-gap MRPC of 140μm gap size with enhanced rate capability. By using a new type of commercially available thin low-resistivity glass, further improvement MRPC rate capability is possible. In order to study the rate capability of the 10-gap MRPC built with this new low-resistivity glass, we have performed tests using the continuous electron beam at ELBE. This 10-gap MRPC, with 160μm gaps, reaches 97% efficiency at 19.2kV and a time resolution of 36ps at particle fluxes near 2kHz/cm2. At a flux of 100kHz/cm2, the efficiency is still above 95% and a time resolution of 50ps is obtained, which would fulfil the requirement of CBM TOF system.

Neutron beam line for TOF measurements at the Spanish National Accelerator Lab (CNA)

A few years ago, the Spanish National Accelerator Lab (CNA) developed the first accelerator-based neutron facility in Spain called HiSPANoS (HiSPAlis Neutron Source). The first applications of the line were related to integral measurements applied to nuclear astrophysics, dosimetry and single event effects produced by neutrons in electronic devices. The successful of HiSPANoS pushed the enhancement of the facility. In collaboration with the NEC® Company, two devices were designed for pulsing ion beams (Chopper) and for compressing in time (Buncher) the pulsed beams. The Chopper-Buncher system has been already installed and commissioned. Proton and deuteron beams are delivered with repetition rates from 62.5 kHz to 2 MHz and 1 ns pulse width. In addition, a new line of the 3 MV Tandem Pelletron accelerator was designed for neutron time-of-flight (TOF) experiments. Conventional devices and a dedicated Pick-Up for timing measurements form the new line. In order to check the performance of the whole TOF system, we have carried out the measurement of the neutron spectrum produced by 7Li(p,n)7Be reaction at Ep = 1912 keV. Such spectrum has been measured by the TOF technique few times and it can be considered a standard neutron field, in particular in nuclear astrophysics. The first result of such experiment performed at CNA is shown in some detail. The excellent performance of the accelerator, the Chopper-Buncher system and the acquisition system allow us to offer the TOF line at HiSPANoS-CNA to the neutron community.