We have investigated the tribomechanical properties of ion-beam-densified sol-gel zirconia overlayers on bulk zirconia. Ion irradiation of the sol-gel films leads to hydrogen, oxygen, and carbon losses as indicated by Rutherford backscattering spectrometry and forward recoil energy spectroscopy. Ellipsometry measurements show that the film thickness decreases with increasing dose. The microhardness exhibits an increase and subsequent decrease with dose. Friction measurements along with profilometry measurements indicate that severe abrasive wear of the film takes place in the first 1000 cycles after which point the substrate is in direct contact with the pin.

In November 2014 two in-air 1.5m CHESS Compact Undulator (CCU) magnets built by KYMA S.R.l. were installed in Cornell Electron Storage Ring (CESR) in canted arrangement and after few days of commissioning their regular operation started. CCU magnets are compact, lightweight and cost efficient devices. They have very stable magnetic field integrals independent of deflection parameter value. This feature greatly simplifies the storage ring operation. The CCU concept was developed at Cornell in 2011 and the first 1m in-vacuum CCU magnet was beam-tested in 2012. The article presents CCU concept and some details of the design. It describes also the layout of CCUs installation in CESR, their performance and characteristics. The current status of operation and future plans are discussed as well. Presently, at CHESS two CCU magnets provide radiation for 5 out of 11 experimental stations.

High-energy X-rays are efficiently focused sagittally by a set of asymmetric Laue (transmission) crystals. We designed, built and commissioned a prototype double Laue monochromator ((111) reflection in Si(100)) optimized for high-energy X-rays (30-60 keV). Here, we report our design of novel prototype sagittal bender and highlight results from recent characterization experiments. The design of the bender combines the tuneable bending control afforded by previous leaf-spring designs with the stability and small size of a four-bar bender. The prototype monochromator focuses a 25 mm-wide white beam incident on the first monochromator crystal to a monochromatized 0.6 mm beam waist in the experimental station. Compared to the flux in the same focal spot with the Bragg crystal (without focusing), the prototype Laue monochromator delivered 85 times more at 30 keV.

We developed, built and beam tested a novel, compact, in-vacuum undulator magnet based on an adjustable phase (AP) scheme. The undulator is 1 m long with a 5mm gap. It has a pure permanent magnet structure with 24.4mm period and 1.1 Tesla maximum peak field. The device consists of two planar magnet arrays mounted on rails inside of a rectangular box-like frame with 156 mm × 146 mm dimensions. The undulator magnet is enclosed in a 273 mm (10.75") diameter cylindrical vacuum vessel with a driver mechanism placed outside. In May 2012 the CHESS Compact Undulator (CCU) was installed in Cornell Electron Storage Ring and beam tested. During four weeks of dedicated run we evaluated undulator radiation properties as well as magnetic, mechanical and vacuum properties of the undulator magnet. We also studied the effect of the CCU on storage ring beam. The spectral characteristics and intensity of radiation were found to be in very good agreement with expected. The magnet demonstrated reproducibility of undulator parameter K at 1.4 × 10−4 level. It was also found that the undulator K. parameter change does not affect electron beam orbit and betatron tunes.

Energy-Recovery Linacs (ERLs) are proposed as drivers for hard x-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. Cornell University has pioneered the design and hardware for ERL lightsources. This preparatory research for ERL-lightsource construction will be discussed. Important milestones have been achieved in Cornell’s prototype ERL injector, including the production of a prototype SRF cavity that exceeds design specifications, the regular production of long-lived and low emittance cathodes, the acceleration of ultra-low emittance bunches, and the world-record of 65 mA current from a photoemission DC gun. We believe that demonstration of the practical feasibility of these technologies have progressed sufficiently to allow the construction of an ERLbased lightsource like that described in Ref [1].

We developed, built and beam tested a novel, compact, in-vacuum undulator magnet based on an adjustable phase (AP) scheme. The undulator is 1 m long with a 5mm gap. It has a pure permanent magnet structure with 24.4mm period and 1.1 Tesla maximum peak field. The device consists of two planar magnet arrays mounted on rails inside of a rectangular box-like frame with 156 mm x 146 mm dimensions. The undulator magnet is enclosed in a 273 mm (10.75”) diameter cylindrical vacuum vessel with a driver mechanism placed outside. In May 2012 the CHESS Compact Undulator (CCU) was installed in Cornell Electron Storage Ring and beam tested. During four weeks of dedicated run we evaluated undulator radiation properties as well as magnetic, mechanical and vacuum properties of the undulator magnet. We also studied the effect of the CCU on storage ring beam. The spectral characteristics and intensity of radiation were found to be in very good agreement with expected. The magnet demonstrated reproducibility of undulator parameter K at 1.4 x10 -4 level. It was also found that the undulator K parameter change does not affect electron beam orbit and betatron tunes.

We have created and tested a compact integrated X-ray beam intensity and position monitor using Ar-gas scintillation. The light generated inside the device's cavity is detected by diametrically opposed PIN diodes located above and below the beam. The intensity is derived from the sum of the top and bottom signals, while the beam position is calculated from the difference-over-sum of the two signals. The device was tested at Cornell High Energy Synchrotron Source with both 17 keV and 59 keV x-rays. For intensity monitoring, the Ar-scintillation monitor performance is comparable to standard ion chambers in terms of precision. As an X-ray beam position monitor the new device response is linear with vertical beam position over a 2 mm span with a precision of 2 μm.

CHESS has pioneered the development of X-ray Video Beam Position Monitors (VBPMs). Unlike traditional photoelectron beam position monitors that rely on photoelectrons generated by the fringe edges of the X-ray beam, with VBPMs we collect information from the whole cross-section of the X-ray beam. VBPMs can also give real-time shape/size information.We have developed three types of VBPMs:(1) VBPMs based on helium luminescence from the intense white X-ray beam. In this case the CCD camera is viewing the luminescence from the side.(2) VBPMs based on luminescence of a thin (similar to 50 micron) CVD diamond sheet as the white beam passes through it. The CCD camera is placed outside the beam line vacuum and views the diamond fluorescence through a viewport.(3) Scatter-based VBPMs. In this case the white X-ray beam passes through a thin graphite filter or Be window.. The scattered X-rays create an image of the beam's footprint on an X-ray sensitive fluorescent screen using a slit placed outside the beam line vacuum.For all VBPMs we use relatively inexpensive 1.3 Mega-pixel CCD cameras connected via USB to a Windows host for image acquisition and analysis. The VBPM host computers are networked and provide live images of the beam and streams of data about the beam position, profile and intensity to CHESS's signal logging system and to the CHESS operator.The operational use of VBPMs showed great advantage over the traditional BPMs by providing direct visual input for the CHESS operator. The VBPM precision in most cases is on the order of similar to 0.1 micron. On the down side, the data acquisition frequency (50-1000ms) is inferior to the photoelectron based BPMs. In the future with the use of more expensive fast cameras we will be able create VBPMs working in the few hundreds Hz scale.

Synchrotron-based x-ray radiation has been utilized to measure time-resolved x-ray excited optical luminescence (TR-XEOL) from InGaN/GaN multiple quantum well (MQW) structures. Excess carrier recombination lifetimes were determined for MQWs grown on conventional c-plane as well as on non-polar m-plane substrates. In addition, the simultaneous measurement of XEOL and x-ray fluorescence reveals an interaction between inner-core excitations of Si impurities and bound exciton recombination in doped GaN-based device structures. Furthermore, the TR-XEOL characterization technique were also applied to InGaN/GaN MQWs grown on GaN inverted pyramid structures.

In order to accurately measure the photon flux and to assist in aligning the beam, we have designed a modified beamstop device based on a photo diode integrated with the beamstop. The beamstop contains a small CdWO4 crystal that completely stops the X-rays and at the same time produces photoluminescence proportional to the X-ray flux. The light is then guided to a photosensitive diode using a flexible light pipe to monitor the flux. With this device we achieve the goal of stopping the primary X-ray beam and simultaneously monitoring the X-ray intensity, thus eliminating the need for integrating ion-chambers into the capillary or collimator mount.

At CHESS' A, F and G wiggler beam lines three new video beam position monitors (VBPMs) have been commissioned. These new VBPMs utilize X-rays scattered from the graphite filter (A and F line) or from a beryllium window (C-line) as the white wiggler beam passes through them. As the X-rays scatter in all directions from the scattering medium, a slit camera creates an image of the beam's footprint on a fluorescent screen. This image is then viewed by a CCD camera and analyzed using a computer program to calculate the intensity centroid, the beam profile and integrated intensity. These data are delivered to the CHESS signal archiving system for storage and display.The new systems employ digital cameras. These cameras are free of the noise inherent to the analog systems with long video signal connections. As a result, the beam position data delivered by the new systems are more reliable and accurate as shown by beam position traces using different beam position monitors on the same beam line. (C) 2010 Elsevier B.V. All rights reserved.

Modern synchrotron X-ray sources produce many kilowatts of power, most of which are absorbed by the first optical elements of the monochromators. As a result, the monochromator crystal deforms (creating a heat bump), leading to severe degradation of the monochromator performance. This problem has been known for decades and various methods have been developed to lessen the effect of heat bumps by implementing various internal cooling methods for the crystal as well as using crystals with superior heat conductivity [1].

A new method of beam position monitoring for white synchrotron X-ray radiation has been developed. This method utilizes X-rays scattered from a graphite filter originally placed in the beam's path to absorb the low-energy portion of the white beam. The graphite filter acts as an optical source plane for scattered X-rays at the beam's footprint. The scattered X-rays exit the vacuum chamber and an image of the beam footprint is created using a pin-hole camera arrangement in combination with a phosphor screen and a CCD camera. The CCD camera records the image frames of the X-ray footprint from which a centroid position of the intensity is calculated. With proper calibration, the centroid position is easily converted to a beam position in microns. We have found that the intrinsic precision for determining the centroid position of an LED image of the camera system on an optical bench is about 0.06 microns.The new beam position monitor has been tested during a dedicated machine study when the X-ray beam position was changed by small amounts using local positron beam position controls.. The measurement error (standard deviation) of the actual X-ray beam position measurement was about 0.6 microns. In addition to providing beam position information the new device also provides vertical beam intensity profile and total beam intensity. (C) 2010 Elsevier B.V. All rights reserved.

beam dynamics in the presence of electron cloud effects. These new instruments are also required to develop low emittance beam conditions which are key to the success of Differential Position Accuracy Channel-to-Channel Sampling Time Accuracy BPM Tilt Errors (after correction) 10 μm 10 ps 10 mrad the damping ring design for the International Linear Collider. This poster will detail some of the architecture and tools which have been developed to support these efforts. Experiment Specific Instruments •Server/client code •Multi Language Functions •Lab wide networking •Hardware interface designs

Synchrotron-based x-ray radiation at Cornell High Energy Synchrotron Source (CHESS A2 beamline) was used to excite luminescence spectra in InGaN/GaN multiple quantum well (MQW) structures for optoelectronic devices. Both, cw and time-resolved techniques have been performed in detecting the x-ray excited optical luminescence (XEOL) signal. The peak of XEOL for GaN layers coincides with that for conventional PL obtained with a laser excitation, while the XEOL peak for the InGaN active region has a 50 nm shift compared to spectra measured with laser-based PL and cathode-luminescence. Time-resolved measurements were done on XEOL spectra using a streak camera. The temporal structure of the x-ray synchrotron beam at CHESS permits exciton life-time measurements in a broad range from 0.5 ns up to a few microseconds. We determined that GaN exciton lifetime varies between 1.3 and 4.5 ns in different structures, while the InGaN exciton lifetime is on the microsecond scale due to higher defect density. Our experimental approach has been extended to the use of x-ray micro-beams. Using this approach a micronsize spot can probe InGaN/GaN device structures simultaneously measuring: (i) x-ray diffraction, (ii) photoluminescence spectra, and (iii) exciton life-times.

We have used a direct optical measurement of the distortion of the first silicon crystal of the CHESS A2 monochromator. The total X-ray power absorbed by the crystal was in the range of 2 to 190 Watts. The X-ray powers measured by a bolometer were in good agreement with the XOP calculations. In-situ optical measurements were used to measure the deformation of the crystal under the heat load between a 3-15° angle of incidence. Simultaneously, ANSYS modeling of the effect of the heat load on the monochromator crystal with the cooling assembly was done. The measured slope error and the surface deformation profiles were in good agreement with the ANSYS simulations. A rocking curve method was used to measure the effect of a heat load on the diffraction properties of the monochromator for a range of beam-defining slit widths. We have found a good correlation between the FWHM of the rocking curves and the slope errors from the optical measurements.

The CHESS A-line 49 pole wiggler produces a total power of 6.6 kW when operating at 5.3 GeV and 200 mA current. Half of this beam is directed into the A2 station operating with both crystal and multilayer optics. The heat load response of the multilayer optics was studied by changing the total power deposited on the first multilayer by varying the slit size. The W/B4C, 300 bi-layers, d=15 angstrom multilayers with the energy resolution of triangle E/E=0.5% were used in our experiment. The results from identical multilayers deposited on Si and SiC substrates, which differ by a factor of two in thermal conductivity, are presented and compared. The thermal distortions of the first multilayer were measured by using recently developed optical in-situ visualization technique and compared with ANSYS simulations. X-ray measurements of the monochromator throughput and effective source size confirm the results of the optical measurements and ANSYS simulations and demonstrate the superior behavior of SiC-substrate based ML optics under high heat load.