金刚石已被开发为通过电离检测带电粒子的材料。它的辐射硬度使其成为在恶劣辐射环境中工作的探测器的有吸引力的材料，例如接近粒子束，如用于束监测和像素顶点探测器的情况。迄今为止，多晶化学气相沉积（CVD）金刚石已被研究用于条形和像素探测器。我们报告的第一次表征的单晶金刚石像素探测器在100 GeV的粒子束在欧洲核子研究中心。探测器由不规则形状的单晶传感器制成，厚度为395 mm，通过凸点焊接与前端读出IC配对，如像素尺寸为50 x 400 mm 2的ATLAS像素探测器中所用。金刚石传感器显示出出色的电荷收集特性：在整个检测器体积上完全收集，干净且窄的信号电荷分布，S/N值>100，命中检测效率为（99.9 +- 0.1）%。在垂直入射下在较短像素方向上的粒子的测量空间分辨率为（8.9 ± 0.1）μ m。
英文摘要：
Diamond has been developed as a material for the detection of charged particles by ionization. Its radiation hardness makes it an attractive material for detectors operated in a harsh radiation environment e.g. close to a particle beam as is the case for beam monitoring and for pixel vertex detectors. Poly-crystalline chemical vapor deposition (CVD) diamond has been studied as strip and pixel detectors so far. We report on a first-time characterization of a single-crystal diamond pixel detector in a 100 GeV particle beam at CERN. The detectors are made from irregularly shaped single crystal sensors, 395mm thick, mated by bump bonding to a front-end readout IC as used in the ATLAS pixel detector with pixel sizes of 50 x 400 mm2. The diamond sensors show excellent charge collection properties: full collection over the entire detector volume, clean and narrow signal charge distributions with a S/N value of >100 and a hit detection efficiency of (99.9 +- 0.1)%. The measured spatial resolution for particles under normal incidence in the shorter pixel direction is (8.9 +- 0.1) um.
Signal and noise of Diamond Pixel Detectors at High Radiation Fluences
CVD金刚石由于其大的带隙和强的晶格结构而具有很强的抗辐射性，是LHC顶点探测器的一种有吸引力的材料选择。特别地，在相互作用点附近操作的像素检测器受益于金刚石的微小漏电流和小像素电容，从而与硅相比具有低噪声系数。另一方面，来自穿越高能粒子的电荷信号在金刚石中比在硅中小约2.2倍。因此，在超过10 $^{15}$ n $_{eq}$ cm $^{-2}$的注量下，与硅相比，定量测定金刚石的信噪比（S/N）是重要的，这是LHC升级所期望的。基于对辐照金刚石传感器的测量和FE-I4像素读出芯片的设计，我们确定了高粒子注量辐照金刚石像素探测器的信号和噪声。为了表征辐射损伤对材料和信号降低的影响，将载流子的平均自由程$λ_{e/h}$的变化确定为辐射通量的函数。我们利用为ATLAS升级开发的FE-I4像素芯片来实际估计预期的噪声系数：给定通量下的预期漏电流来自校准计算，像素电容使用专门开发的芯片（PixCap）测量。我们比较所得的S/N数字与平面硅像素探测器使用公布的电荷损失测量和相同的外推方法，为金刚石。它示出，预期的S/N的金刚石像素探测器与像素间距典型的LHC，超过平面硅像素在超过10 $^{15}$粒子cm $^{-2}$的注量，确切的值仅取决于最大的操作电压假设为辐照硅像素探测器。
We report on performance of chemical vapor deposited (CVD) single crystal diamond plates as side bounce monochromators for high photon energies ($\gtrsim$~20 keV) in the Laue geometry. Several crystals were tested in-operando high-heat-load conditions at A1 undulator station of Cornell High Energy Synchrotron Source. Up to 10$\times$ enhancement in the reflected x-ray flux was observed compared to that delivered by IIa diamond plates grown by high-pressure high-temperature method. Wavefront distortions were measured using analyzer-based x-ray diffraction imaging. Focusing of a portion of the r…
We present the design and initial prototype results of a pixellized proton beam profile monitor for the COMET experiment at J-PARC. The goal of COMET is to look for charged lepton flavor violation by direct muon to electron conversion at a sensitivity of $0^{-19}$. An 8 GeV proton beam pulsed at 100 ns with $10^{10}$ protons/s will be used to create muons through pion production and decay. In the final experiment, the proton flux will be raised to $10^{14}$ protons/sec to increase the sensitivity. These requirements of harsh radiation tolerance and fast readout make diamond a good choice for c…
Artificially-grown diamond crystals have unique properties that make them suitable as solid-state particle detectors and dosimeters in high-radiation environments. We have been using sensors based on single-crystal diamond grown by chemical vapour deposition for dosimetry and beam-loss monitoring at the SuperKEKB collider. Here we describe the assembly and the suite of test and calibration procedures adopted to characterise the diamond-based detectors of this monitoring system. We report the results obtained on 28 detectors and assess the stability and uniformity of response of these devices.
In order to evaluate the charge collection efficiency (CCE) profile of single-crystal diamond devices based on a p type/intrinsic/metal configuration, a lateral Ion Beam Induced Charge (IBIC) analysis was performed over their cleaved cross sections using a 2 MeV proton microbeam. CCE profiles in the depth direction were extracted from the cross-sectional maps at variable bias voltage. IBIC spectra relevant to the depletion region extending beneath the frontal Schottky electrode show a 100% CCE, with a spectral resolution of about 1.5%. The dependence of the width of the high efficiency region …
This paper outlines the results of investigations into the effects of radiation damage in the mini-MALTA prototype. Measurements were carried out at Diamond Light Source using a micro-focus X-ray beam, which scanned across the surface of the device in 2 $\mathrm{μm}$ steps. This allowed the in-pixel photon response to be measured directly with high statistics. Three pixel design variations were considered: one with the standard continuous $\mathrm{n^-}$ layer layout and front-end, and extra deep p-well and $\mathrm{n^-}$ gap designs with a modified front-end. Five chips were measured: one unir…
Next-generation, high-brilliance x-ray photon sources call for new x-ray optics. Here we demonstrate the feasibility of using monolithic diamond channel-cut crystals as high-heat-load, beam-multiplexing, narrow-band, mechanically-stable x-ray monochromators with high-power x-ray beams at cutting-edge, high-repetition-rate x-ray free-electron laser (XFEL) facilities. The diamond channel-cut crystals fabricated and characterized in these studies are designed as two-bounce Bragg reflection monochromators directing 14.4-keV or 12.4-keV x-rays within a 15-meV-bandwidth to $^{57}$Fe or $^{45}$Sc nuc…
Wavefront-preserving x-ray diamond crystal optics are essential for numerous applications in x-ray science. Perfect crystals with flat Bragg planes are a prerequisite for wavefront preservation in Bragg diffraction. However, this condition is difficult to realize in practice because of inevitable crystal imperfections. Here we use x-ray rocking curve imaging to study the smallest achievable Bragg-plane slope errors in the best presently available synthetic diamond crystals and how they compare with those of perfect silicon crystals. We show that the smallest specific slope errors in the best d…
A high-performance fast response deep ultraviolet (UV) photodetectors with interdigitated Ti/Au planar electrodes using a lithography technology has fabricated on homoepitaxial diamond. The device shows a high ultraviolet photocurrent at 213 nm, which is eight orders of magnitude higher than the dark current at the bias voltages of 30 V. In addition, the time-resolved photoresponse measurements using a mechanical method and a pulsed 213 nm laser show that a good cycling, low persistent photoconductivity, and transient time-resolved response of up to 2.4 ns.
The resolution function of a spectrometer based on a strongly bent single crystal (bending radius of 10 cm or less) is evaluated. It is shown that the resolution is controlled by two parameters, (i) the ratio of the lattice spacing of the chosen reflection to the crystal thickness and (ii) a single parameter comprising crystal thickness, its bending radius, and anisotropic elastic constants of the chosen crystal. Diamond, due to its unique elastic properties, can provide notably higher resolution than silicon. The results allow to optimize the parameters of bent crystal spectrometers for the h…
We report fabrication and results of high-resolution X-ray topography characterization of diamond single crystal plates with a large surface area (10$\times$10 mm$^2$) and (111) crystal surface orientation for applications in high-heat-load X-ray crystal optics. The plates were fabricated by laser cutting of the (111) facets of diamond crystals grown using high-pressure high-temperature method. The intrinsic crystal quality of a selected 3$\times$7~mm$^2$ crystal region of one of the studied samples was found to be suitable for applications in wavefront-preserving high-heat-load crystal optics…
We report the fabrication and performance evaluation of single crystal diamond refractive x-ray lenses with a paraboloid of rotation form factor for focusing x-rays in two dimensions simultaneously. The lenses were manufactured using a femtosecond laser micromachining process and tested using x-ray synchrotron radiation. Such lenses were stacked together to form a standard compound refractive lens (CRL). Due to the superior physical properties of the material, diamond CRLs are enabling and indispensable wavefront-preserving primary focusing optics for x-ray free-electron lasers and the next-ge…
Crystal strain variation imposes significant limitations on many quantum sensing and information applications for solid-state defect qubits in diamond. Thus, precision measurement and control of diamond crystal strain is a key challenge. Here, we report diamond strain measurements with a unique set of capabilities, including micron-scale spatial resolution, millimeter-scale field-of-view, and a two order-of-magnitude improvement in volume-normalized sensitivity over previous work [1], reaching $5(2) \times 10^{-8}/\sqrt{\rm{Hz}\cdot\rm{μm}^3}$ (with spin-strain coupling coefficients representi…
We demonstrate the application of two-photon absorption transient current technique to wide bandgap semiconductors. We utilize it to probe charge transport properties of single-crystal Chemical Vapor Deposition (scCVD) diamond. The charge carriers, inside the scCVD diamond sample, are excited by a femtosecond laser through simultaneous absorption of two photons. Due to the nature of two-photon absorption, the generation of charge carriers is confined in space (3-D) around the focal point of the laser. Such localized charge injection allows to probe the charge transport properties of the semico…
