No Arabic abstract
A foil-microchannel plate (MCP) detector, which uses electrostatic lenses and possesses both good position and timing resolutions, has been designed and simulated for beam diagnostics and mass measurements at the next-generation heavy-ion-beam facility HIAF in China. Characterized by low energy loss and good performances of timing and position measurements, it would be located at focal planes in fragment separator HFRS for position monitoring, beam turning, B${rho}$ measurement, and trajectory reconstruction. Moreover, it will benefit the building-up of a magnetic-rigidity-energy-loss-time-of-flight (B${rho}$-$Delta$E-TOF) method at HFRS for high-precision in-flight particle identification (PID) of radioactive isotope (RI) beams on an event-by-event basis. Most importantly, the detector can be utilized for in-ring TOF and position measurements, beam-line TOF measurements at two achromatic foci, and position measurements at a dispersive focus of HFRS, thus making it possible to use two complementary mass measurement methods (isochronous mass spectrometry (IMS) at the storage ring SRing and magnetic-rigidity-time-of-flight (B${rho}$-TOF) at the beam-line HFRS) in one single experimental run.
To achieve high precision and accuracy for mass measurements of exotic nuclei by Time-of-flight (TOF) methods: high-resolution beam-line magnetic-rigidity time-of-flight (B$rho$-TOF) and in-ring isochronous mass spectrometry (IMS), a large-area electrostatic detector which possesses high position resolution and good timing resolution at the same time is developed at the Rare-RI Ring in RIBF, RIKEN Nishina Center, Japan. Besides TOF mass measurements, the detector system will also be used for heavy ion beam trajectory monitoring or momentum measurements for both beam-line and in-ring at the Rare-RI Ring. The position and timing measurements of heavy ions are performed by detecting the secondary electrons (SEs) emitted from a conversion foil during the passage of the ion. The SEs are accelerated and bent with an angle of $90^{circ}$ by electrostatic fields onto a micro-channel-plate (MCP) electron multiplier which is coupled with a position-sensitive delay-line anode. The dependence of the timing and position resolution on applied high voltages of the detector potential plates has been studied systematically via simulation and experimentally. An isochronous condition of secondary electron transmission in the electrostatic field of the detector is chosen to optimize the structure of the detector for high performance. The best achieved timing resolution is less than 50 ps (in $sigma$) and position resolution $sim$ 1 mm (in $sigma$) for 2 dimensions, respectively. The overall efficiency is $sim$ 95$%$ for heavy ion beam and $sim$ 75$%$ for $alpha$ particle from $^{241}$Am source.
We report the development of a fast position-sensitive laser beam detector with a bandwidth that exceeds currently available detectors. The detector uses a fiber-optic bundle that spatially splits the incident beam, followed by a fast balanced photo-detector. The detector is applied to the study of Brownian motion of particles on fast time scales with 1 Angstrom spatial resolution. Future applications include the study of molecule motors, protein folding, as well as cellular processes.
A prototype of a position sensitive photo-detector with 5.6 x 5.6 cm2 detection area readout with 64 Hamamatsu MPPCs (S10931-100P) with 3 x 3 mm2 active area each has been built and tested. The photo-sensors are arranged in a 8 x 8 array with a quadratic mirror light guide on top. The module is currently readout by in-house developed preamplifier boards but employing existing ASIC chips optimized for SiPM readout is also planned. Such a device is one of the candidates to be used for photon detection in the PANDA DIRC detectors.
We are developing position sensitive silicon detectors (PSDs) which have an electrode at each of four corners so that incident position of a charged particle can be obtained with signal from the electrodes. It is expected that the position resolution of the electromagnetic calorimeter (ECAL) of the ILD detector will be improved by introducing PSDs to detection layers. We have been developing the PSDs for several years. In the previous production we found that the charge separation is not optimally done due to the readout impedance. To solve the issue, we produced new PSDs with higher surface resistance with an additional resistive layer on the surface. We also implemented several techniques to decrease position distortion and increase signal-to-noise ratio which are essential for the optimal position resolution. The measurements on the prototype sensors are ongoing, including radiation source measurement and laser measurement using an ASIC for silicon pad detectors.
We report on the construction of a UHV compatible 40 mm active diameter detector based on micro channel plates and assembled directly on the feed-throughs of a DN63CF flange. It is based on the charge division technique and uses a standard two inch Si wafer as a collector. The front end electronic is placed directly on the air side of the flange allowing excellent immunity to noise and a very good timing signal with reduced ringing. The important aberrations are corrected empirically providing and absolute positioning accuracy of 500 $mu$m while a 150 $mu$m resolution is measured in the center.