Electro-optic techniques for longitudinal electron bunch diagnostics

Electro-optic techniques are becoming increasingly important in ultrafast electron bunch longitudinal diagnostics and have been successfully implemented at various accelerator laboratories. The longitudinal bunch shape is directly obtained from a single-shot, non-intrusive measurement of the temporal electric field profile of the bunch. Further- more, the same electro-optic techniques can be used to measure the temporal profile of terahertz / far-infrared opti- cal pulses generated by a CTR screen, at a bending magnet (CSR), or by an FEL. This contribution summarizes the re- sults obtained at FELIX and FLASH

Single shot longitudinal bunch profile measurements by temporally resolved electro-optical detection

For the high gain operation of a SASE FEL, extremely short electron bunches are essential to generate sufficiently high peak currents. At the superconducting linac of FLASH at DESY, we have installed an electro- optic measurement system to probe the time structure of the electric field of single ~100 fs electron bunches. In this technique, the field induced birefringence in an electro-optic crystal is encoded on a chirped picosecond laser pulse. The longitudinal electric field profile of the electron bunch is then obtained from the encoded optical pulse by a single shot cross correlation with a 35 fs laser pulse using a second harmonic crystal (temporal decoding). An electro-optical signal exhibiting a feature with 118 fs FWHM was observed, and this is close to the limit of resolution due to the material properties of the particular electro-optic crystal used. The measured electro-optic signals are compared to bunch shapes simultaneously measured with a transverse deflecting cavity

Benchmarking of electro-optic monitors for femtosecond electron bunches

The longitudinal profiles of ultrashort relativistic electron bunches at the soft x-ray free-electron laser FLASH have been investigated using two single-shot detection schemes: an electro-optic (EO) detector measuring the Coulomb field of the bunch and a radio-frequency structure transforming the charge distribution into a transverse streak. A comparison permits an absolute calibration of the EO technique. EO signals as short as 60 fs (rms) have been observed, which is a new record in the EO detection of single electron bunches and close to the limit given by the EO material properties

Single-shot longitudinal bunch profile measurements at FLASH using electro-optic detection:experiment, simulation, and validation

At the superconducting linac of FLASH at DESY, we have installed an electro-optic (EO) experiment for single- shot, non-destructive measurements of the longitudinal electric charge distribution of individual electron bunches. The time profile of the electric bunch field is electro- optically encoded onto a chirped titanium-sapphire laser pulse. In the decoding step, the profile is retrieved either from a cross-correlation of the encoded pulse with a 30 fs laser pulse, obtained from the same laser (electro- optic temporal decoding, EOTD), or from the spectral intensity of the transmitted probe pulse (electro-optic spectral decoding, EOSD). At FLASH, the longitudinally compressed electron bunches have been measured during FEL operation with a resolution of better than 50 fs. The electro-optic process in gallium phosphide was numerically simulated using as input data the bunch shapes determined with a transverse-deflecting RF structure. In this contribution, we present electro-optically measured bunch profiles and compare them with the simulation

Beam alignment techniques based on the current multiplication effect in photoconductors Third summary technical progress report, 15 Nov. 1966 - 15 Oct. 1967

Beam alignment techniques developed for infrared sensitive single crystal germanium to study multiplication effect in photoconductor

High-accuracy global time and frequency transfer with a space-borne hydrogen maser clock

A proposed system for high-accuracy global time and frequency transfer using a hydrogen maser clock in a space vehicle is discussed. Direct frequency transfer with a accuracy of 10 to the minus 14th power and time transfer with an estimated accuracy of 1 nsec are provided by a 3-link microwave system. A short pulse laser system is included for subnanosecond time transfer and system calibration. The results of studies including operational aspects, error sources, data flow, system configuration, and implementation requirements for an initial demonstration experiment using the Space Shuttle are discussed

Blood pressure differences between home monitoring and daytime ambulatory values and their reproducibility in treated hypertensive stroke and TIA patients

Background: Guidelines recommend ambulatory or home blood pressure monitoring to improve hypertension diagnosis and monitoring. Both these methods are ascribed the same threshold values, but whether they produce similar results has not been established in certain patient groups. Methods: Adults with mild/moderate stroke or transient ischemic attack (N = 80) completed 2 sets of ambulatory and home blood pressure monitoring. Systolic and diastolic blood pressure values from contemporaneous measurements were compared, and the limits of agreement were assessed. Exploratory analyses for predictive factors of any difference were conducted. Results: Daytime ambulatory blood pressure values were consistently lower than home values, the mean difference in systolic blood pressure for initial ambulatory versus first home monitoring was −6.6 ± 13.5 mm Hg (P≤.001), and final ambulatory versus second home monitoring was −7.1 ± 11.0mm Hg (P≤.001). Mean diastolic blood pressure differences were −2.1 ± 8.5mm Hg (P=.03) and −2.0 ± 7.2mm Hg (P=.02). Limits of agreement for systolic blood pressure were −33.0 to 19.9mm Hg and −28.7 to 14.5mm Hg for the 2 comparisons and for DBP were −18.8 to 14.5mm Hg and −16.1 to 12.2mm Hg, respectively. The individual mean change in systolic blood pressure difference was 11.0 ± 8.3mm Hg across the 2 comparisons. No predictive factors for these differences were identified. Conclusions: Daytime ambulatory systolic and diastolic blood pressure values were significantly lower than home monitored values at both time points. Differences between the 2 methods were not reproducible for individuals. Using the same threshold value for both out-of-office measurement methods may not be appropriate in patients with cerebrovascular disease

Orbit transfer using Theory of Functional Connections via change of variables

This work shows that a class of astrodynamics problems subject to mission constraints can be efficiently solved using the Theory of Functional Connections (TFC) mathematical framework by a specific change of coordinates. In these problems, the constraints are initially written in non-linear and coupled mathematical forms using classical rectangular coordinates. The symmetries of the constrained problem are used to select a new system of coordinates that transforms the non-linear constraints into linear. This change of coordinates is also used to isolate the components of the constraints. This way the TFC technique can be used to solve the ordinary differential equations governing orbit transfer problems subject to mission constraints. Specifically, this paper shows how to apply the change of coordinates method to the perturbed Hohmann-type and the one-tangent burn transfer problems.Comment: Paper submitted to The European Physical Journal Special Topic

Excursions in Indiana Geology

Indiana Geological Survey Guidebook 12Indiana lies wholly within the Central Lowland Province and thus calls to mind widespread, thin, nearly flat-lying Paleozoic rocks, major unconformities, and extensive plains. These features express epeirogenic submergences of the central part of the continent, long periods of general stability, and, nevertheless, repeatedly interrupted episodes of sedimentation and landform sculpture. Outstanding among these episodes was continental glaciation that carried to the Ohio River. Receiving ice from two principal directions the State's surface nearly everywhere attests to its latest experience, most obviously in the form of a great till plain that is interrupted in its gross appearance by end moraines, valley trains, and ice-contact deposits. Structurally, the State lies athwart a broad crestal area, the Cincinnati Arch, which separates the Michigan Basin on the north from the Illinois Basin on the southwest. Some structural instability, manifest as long ago as Precambrian time, is evident in such sedimentational or second-rank structural features as lithofacies, Silurian-Devonian and Mississippian-Pennsylvanian unconformities that change both locally and regionally in magnitude, and faulting. The more recent erosional record reflects structural history as well, and Paleozoic rocks from middle Ordovician to middle Pennsylvanian in age crop out at the bedrock surface according to their order of superposition. The Paleozoic units west and south of the Cincinnati Arch have special interest on these excursions. Their truncated edges, having differing resistances, are expressed alternately by open vales of gentle relief and uplands consisting of partly dissected westward-facing dip slopes and rugged forested scarps. Within easy range of Bloomington we can demonstrate much of the variety of geologic form characteristic of the State. Crossing the regional strike and the boundary between driftless and glaciated areas, the first day's excursion (inside front cover) is generally eastward to traverse bedrock of Mississippian to Silurian age and drifts assigned to the Kansan, Illinoian, and Wisconsin Stages. It emphasizes the State's most widely known natural product, the Indiana Limestone, and relationships of physiography to bedrock and drift. The second day's excursion (inside back cover) is northwestward from Bloomington and crosses younger bedrock (to middle Pennsylvanian in age). It emphasizes the Mississippian-Pennsylvanian unconformity, stratigraphic relationships of drifts, and some of the newest methods of coal mining and land reclamation.Indiana Geological Survey Indiana Department of Natural Resources American Association of State Geologist