Incom (United States)

The solenoidal large intensity device (SoLID) at Jefferson Lab will push the boundaries of luminosity for a large-acceptance detector, which necessitates the use of a light-gas threshold Cherenkov counter for online event selection. Due to the high luminosity, the single-photon background rate in this counter can exceed 160 kHz/cm2 at the photosensors. Therefore, it is essential to validate the high-rate limits of the planned photosensors and readout electronics in order to mitigate the risk of failure. We report on the design and an early set of studies carried out using a small Cherenkov counter in a high-rate environment up to 60 kHz/cm2, in Hall C at Jefferson Lab. Commercially available multi-anode photomultipliers (MaPMT) and low-cost large-area picosecond photodetectors (LAPPD) were tested using the JLab FADC250 modules for readout. The test beam results show that the MaPMT array and the internal stripline LAPPD can detect and identify single-electron and pair-production events in high-rate environments. Due to its higher quantum efficiency, the MaPMT array provided a better separation between the single-electron and the pair-production events compared to the internal stripline LAPPD. A GEANT4 simulation confirms the beam test performance of our counter device.

Microchannel plate based detectors are widely used for photon counting spectroscopy and imaging in astronomical, high energy physics and remote sensing applications^1-15. We present progress in the development of imaging cross strip readout detectors using novel microchannel plates functionalized by atomic layer deposition (ALD). ALD microchannel plates have established formats of 10 cm with 10 μm pore sizes and 20 cm with 20 μm pores. ALD MCPs show with high quantum efficiency (>50% @115 nm) using opaque alkali halide photocathodes and very low background levels (0.05 events cm^-2) have been achieved. Readout systems have also evolved and now cross-strip anodes and encoding electronics enable high spatial resolution (<20 μm) at low gain (10⁶) and over large formats (10 cm) with high dynamic range (>5 MHz). These characteristics are essential for UV instrument concepts currently under study for NASA including the Large UV/Optical/IR Surveyor (LUVOIR)¹⁶, the Habitable Exoplanet Imaging Mission (HABEX)¹⁶, and Cosmic Evolution Through UV Spectroscopy (CETUS)¹⁶.

ALD-GCA-MCPs are a technology advancement that affords microchannel plates (MCPs) with significant performance benefits compared to conventional MCP technology. Incom now routinely produces ALD-GCA-MCPs with dimensions up to 20 cm x 20 cm. Notable advancements and benefits over conventional lead-oxide based MCPs are larger size and higher mechanical stability, high and stable gain (>1e4for single MCP @ 1000 V, stable gain to ≥ 1 C/cm2 extracted charge), low dark counts (≤ 0.05 cts/sec/cm2), ~3x lower gamma-ray sensitivity, and the unique ability to individually customize and control the MCP resistance and secondary electron emission (SEE) amplification characteristics. ALD-GCA-MCPs find application in a variety of photon and charged particle counting applications and are particularly suited for applications that require fast timing, high spatial resolution, radiation hardness, and long detector life times, such as Ion-TOF, electron spectroscopies, and a variety of other analytical instruments. They can also be incorporated into low-power, low-background photodetectors suitable for applications in extreme environments such as remote sensing applications in rugged environments, in space flight instrumentation, as well as in high-energy physics and nuclear physics experiments. In this paper we will provide a brief ALD-GCA-MCP technology overview highlighting recent developments that focused on improving the glass capillary array (GCA) substrate, and their implications for large-area photodetectors and spectrometers used in nuclear and high energy physics, space science, and other sensing applications.

Sealed tube MCP detectors have provided a valuable platform for high spatial resolution photon counting detectors. Specifically, electronic readout microchannel plate (MCP) based sensors have been used as photon counting, imaging, event time tagging detectors for astronomy, time resolved biological imaging, imaging LIDAR, Cherenkov (RICH), scintillation detection, and neutron imaging [1]–[10]. For future applications we have been developing novel atomic layer deposited MCPs, UV optimized photocathodes and high resolution cross strip readouts for sealed tube detectors. The Photonis Planacon is a useful sealed detector format (~50 mm square active area) to employ and demonstrate these novel technologies. The Planacon standard geometry has been used, but the standard anode pad array is replaced with a cross strip anode that demonstrates ~20 µm FWHM spatial resolution for single photon events at electron gains of the order 106. Atomic layer deposited MCPs with 10µm pores have been used in place of conventional MCPs, providing tight pulse amplitude distributions, enhanced gain stability and reduced gamma ray sensitivity. The entrance window (Sapphire or MgF2) permits the high UV sensitivity of bialkali photocathodes (>30% @180nm) to be utilized. Event encoding electronics implemented in surface mount components also provides high resolution imaging at event rates of up to 5 MHz. ASIC versions of the encoding electronics are in the prototype phase and show considerable promise for enhanced performance with lower power and smaller footprints.

Este articulo tiene como objetivo presentar una discusion sobre el caracter critico y activo de la poblacion gitana en cuanto audiencia. Para ello, se hara una revision teorica sobre los estudios de audiencia que interpretan el publico desde una perspectiva de pasividad o de agencia y tambien aquellos que debaten las particularidades del consumo mediatico por las minorias. En los resultados, se presentaranlas reflexiones de miembros de este colectivo sobre como su pueblo es representado en los contenidos informativos de los medios de comunicacion de Espana. La metodologia utilizada ha sidolasentrevistas semi-estructuradas con 20 gitanos y gitanas de la provincia de Barcelona entre los anos 2017 y 2019. Como conclusion, destacamos la capacidad critica de los interlocutores en evaluar lo que se esta produciendo sobre ellos en los media tradicionalesy tambien el uso del entorno digital en la interaccion y produccion de contenidos propios.

Using data from OECD’s PISA, Eurostat and World Bank’s WDI, we explore how child cognitive outcomes at the aggregate country level are related to macroeconomic conditions, specifically government education expenditures and early education experience. We find that both government expenditures in education and attendance to early child care are associated with better later school performance. We also consider different childcare characteristics such as duration and quality, which appear to have significant effects Our results may imply that policies encouraging childcare expansion should also take into account quality issues.

We have designed and tested a robust 20 x 20 cm^2 thin metal film internal anode capacitively coupled to an external array of signal pads or micro-strips for use in fast microchannel plate photodetectors. The internal anode, in this case a 10nm-thick NiCr film deposited on a 96% pure Al_2O_3 3mm-thick ceramic plate and connected to HV ground, provides the return path for the electron cascade charge. The multi-channel pickup array consists of a printed-circuit card or glass plate with metal signal pickups on one side and the signal ground plane on the other. The pickup can be put in close proximity to the bottom outer surface of the sealed photodetector, with no electrical connections through the photodetector hermetic vacuum package other than a single ground connection to the internal anode. Two pickup patterns were tested using a small commercial MCP-PMT as the signal source: 1) parallel 50 Ohm 25-cm-long micro-strips with an analog bandwidth of 1.5 GHz, and 2) a 20 x 20 cm^2 array of 2-dimensional square `pads' with sides of 1.27 cm or 2.54 cm. The rise-time of the fast input pulse is maintained for both pickup patterns. For the pad pattern, we observe 80% of the directly coupled amplitude.

The large-area picosecond photodetector (LAPPD TM ) is an ultrafast imaging detector with single-photon sensitivity. The time resolution approaches the coherence time of light filtered with dielectric-layer interference filters, and so, the detector can resolve photon occupations in each longitudinal mode of light. Furthermore, if used with diffraction-limited optics matched to the spatial resolution, the detector can also resolve about 400 by 400 transverse modes. LAPPD TM is thus an enabling technology for quantum optics where photon occupation numbers in each electromagnetic-field mode in 6-dimensional phase space are relevant, for example photon- correlation experiments (Hanbury Brown - Twiss, or ghost imaging).