1,779 research outputs found

    Methyl N-(2-bromo-4-chlorophenyl)carbamate

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    In the title molecule, C8H7BrClNO2, the bromochlorophenyl ring is inclined to the methylcarbamate unit by 32.73 (7). In the crystal, N—HO hydrogen bonds form chains of molecules parallel to [100]

    Charge collection properties of irradiated depleted CMOS pixel test structures

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    Edge-TCT and charge collection measurements with passive test structures made in LFoundry 150 nm CMOS process on p-type substrate with initial resistivity of over 3 kΩ\Omegacm are presented. Measurements were made before and after irradiation with reactor neutrons up to 2\cdot1015^{15} neq_{\mathrm{eq}}/cm2^2. Two sets of devices were investigated: unthinned (700 μ\mum) with substrate biased through the implant on top and thinned (200 μ\mum) with processed and metallised back plane. Depleted depth was estimated with Edge-TCT and collected charge was measured with 90^{90}Sr source using an external amplifier with 25 ns shaping time. Depleted depth at given bias voltage decreased with increasing neutron fluence but it was still larger than 70 μ\mum at 250 V after the highest fluence. After irradiation much higher collected charge was measured with thinned detectors with processed back plane although the same depleted depth was observed with Edge-TCT. Most probable value of collected charge of over 5000 electrons was measured also after irradiation to 2\cdot1015^{15} neq_{\mathrm{eq}}/cm2^2. This is sufficient to ensure successful operation of these detectors at the outer layer of the pixel detector in the ATLAS experiment at the upgraded HL-LHC

    Gain Recovery in Heavily Irradiated Low Gain Avalanche Detectors by High Temperature Annealing

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    Studies of annealing at temperatures up to 450^\circC with LGADs irradiated with neutrons are described. It was found that the performance of LGADs irradiated with 1.5e15 n/cm2^2 was already improved at 5 minutes of annealing at 250^\circC. Isochronal annealing for 30 minutes in 50^\circC steps between 300^\circC and 450^\circC showed that the largest beneficial effect of annealing is at around 350^\circC. Another set of devices was annealed for 60 minutes at 350^\circC and this annealing significantly increased Vgl_{\mathrm{gl}}. The effect is equivalent to reducing the effective acceptor removal constant by a factor of \sim 4. Increase of Vgl_{\mathrm{gl}} is the consequence of increased effective space charge in the gain layer caused by formation of electrically active defects or re-activation of interstitial Boron atoms

    Timing performance of small cell 3D silicon detectors

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    A silicon 3D detector with a single cell of 50x50 um2 was produced and evaluated for timing applications. The measurements of time resolution were performed for 90Sr electrons with dedicated electronics used also for determining time resolution of Low Gain Avalanche Detectors (LGADs). The measurements were compared to those with LGADs and also simulations. The studies showed that the dominant contribution to the timing resolution comes from the time walk originating from different induced current shapes for hits over the cell area. This contribution decreases with higher bias voltages, lower temperatures and smaller cell sizes. It is around 30 ps for a 3D detector of 50x50 um2 cell at 150 V and -20C, which is comparable to the time walk due to Landau fluctuations in LGADs. It even improves for inclined tracks and larger pads composed of multiple cells. A good agreement between measurements and simulations was obtained, thus validating the simulation results
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