WorldWideScience

Sample records for bright collimated light

  1. Compact collimators for high brightness blue LEDs using dielectric multilayers

    NARCIS (Netherlands)

    Cornelissen, H.J.; Ma, H.; Ho, C.; Li, M.; Mu, C.

    2011-01-01

    A novel method is presented to inject the light of millimeter-sized high-brightness blue LEDs into light guides of submillimeter thickness. Use is made of an interference filter that is designed to pass only those modes that will propagate in the light guide by total internal reflection. Other modes

  2. Bright Lights, Big Cities

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Overabundant lighting has become another pollution source in the Chinese cities The glow of electric lights illuminating the nights of ever-brighter cities has been regarded as one of the signs of prosperity and modern civilization.

  3. [Bright light therapy for elderly].

    Science.gov (United States)

    Okawa, Masako

    2015-06-01

    Bright light therapy (BLT) holds considerable promise for sleep problems in the elderly. BLT for community-dwelling patients with Alzheimer's disease showed significant improvement in sleep parameters. In the institutional setting, BLT was effective in reducing daytime nap duration. Morning BLT was found to advance the peak circadian rhythm and increase activity level in daytime and melatonin level at night. Light therapy could be used in combination with other nonpharmacological methods such as social activities, outside walking, physical exercises, which showed greater effects than independent BLT on sleep and cognitive function. BLT treatment strategy was proposed in the present paper. We should pay more attentions to BLT in community setting for mental and physical well-being. PMID:26065132

  4. Electron Beam Collimation for the Next Generation Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Steier, C.; Emma, P.; Nishimura, H.; Papadopoulos, C.; Sannibale, F.

    2013-05-20

    The Next Generation Light Source will deliver high (MHz) repetition rate electron beams to an array of free electron lasers. Because of the significant average current in such a facility, effective beam collimation is extremely important to minimize radiation damage to undulators, prevent quenches of superconducting cavities, limit dose rates outside of the accelerator tunnel and prevent equipment damage. This paper describes the early conceptual design of a collimation system, as well as initial results of simulations to test its effectiveness.

  5. Collimated Light Source Using Patterned Organic Light-Emitting Diodes and Microlens

    Science.gov (United States)

    Sukekazu Aratani,; Masaya Adachi,; Masao Shimizu,; Tatsuya Sugita,; Toshinari Shibasaki,; Katsusuke Shimazaki,

    2010-04-01

    We developed for the first time a collimated organic light-emitting diode (OLED) light source using a patterned OLED and a microlens. The structure of the collimated OLED light source was designed by conventional ray-tracking simulation. We demonstrated that the collimated OLED light source enhanced the luminance of a liquid crystal display (LCD) with a low aperture ratio by a factor of more than two compared with a conventional OLED light source, which was not patterned. The collimated OLED light source with the patterned OLED and microlens is thus very effective for achieving a highly efficient LCD with OLED backlight.

  6. Increasing the brightness of light sources

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Ling

    2006-11-16

    In this work the principle of light recycling is applied to artificial light sources in order to achieve brightness enhancement. Firstly, the feasibilities of increasing the brightness of light sources via light recycling are examined theoretically, based on the fundamental laws of thermodynamics including Kirchhoff's law on radiation, Planck's law, Lambert-Beer's law, the etendue conservation and the brightness theorem. From an experimental viewpoint, the radiation properties of three different kinds of light sources including short-arc lamps, incandescent lamps and LEDs characterized by their light-generating mechanisms are investigated. These three types of sources are used in light recycling experiments, for the purpose of 1. validating the intrinsic light recycling effect in light sources, e. g. the intrinsic light recycling effect in incandescent lamps stemming from the coiled filament structure. 2. acquiring the required parameters for establishing physical models, e.g. the emissivity/absorptivity of the short-arc lamps, the intrinsic reflectivity and the external quantum efficiency of LEDs. 3. laying the foundations for designing optics aimed at brightness enhancement according to the characteristics of the sources and applications. Based on the fundamental laws and experiments, two physical models for simulating the radiance distribution of light sources are established, one for thermal filament lamps, the other for luminescent sources, LEDs. As validation of the theoretical and experimental investigation of the light recycling effect, an optical device, the Carambola, is designed for achieving deterministic and multiple light recycling. The Carambola has the function of a concentrator. In order to achieve the maximum possible brightness enhancement with the Carambola, several combinations of sources and Carambolas are modelled in ray-tracing simulations. Sources with different light-emitting mechanisms and different radiation properties

  7. Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise

    OpenAIRE

    Youngstedt, Shawn D.; Kline, Christopher E.; Elliott, Jeffrey A; Zielinski, Mark; Devlin, Tina M.; Moore, Teresa A.

    2016-01-01

    Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness...

  8. Hybrid quantum repeater using bright coherent light.

    Science.gov (United States)

    van Loock, P; Ladd, T D; Sanaka, K; Yamaguchi, F; Nemoto, Kae; Munro, W J; Yamamoto, Y

    2006-06-23

    We describe a quantum repeater protocol for long-distance quantum communication. In this scheme, entanglement is created between qubits at intermediate stations of the channel by using a weak dispersive light-matter interaction and distributing the outgoing bright coherent-light pulses among the stations. Noisy entangled pairs of electronic spin are then prepared with high success probability via homodyne detection and postselection. The local gates for entanglement purification and swapping are deterministic and measurement-free, based upon the same coherent-light resources and weak interactions as for the initial entanglement distribution. Finally, the entanglement is stored in a nuclear-spin-based quantum memory. With our system, qubit-communication rates approaching 100 Hz over 1280 km with fidelities near 99% are possible for reasonable local gate errors.

  9. Solar concentrator with integrated tracking and light delivery system with collimation

    Energy Technology Data Exchange (ETDEWEB)

    Maxey, Lonnie Curt

    2015-06-09

    A solar light distribution system includes a solar light concentrator that is affixed externally to a light transfer tube. Solar light waves are processed by the concentrator into a collimated beam of light, which is then transferred through a light receiving port and into the light transfer tube. A reflector directs the collimated beam of light through the tube to a light distribution port. The interior surface of the light transfer tube is highly reflective so that the light transfers through the tube with minimal losses. An interchangeable luminaire is attached to the light distribution port and distributes light inside of a structure. A sun tracking device rotates the concentrator and the light transfer tube to optimize the receiving of solar light by the concentrator throughout the day. The system provides interior lighting, uses only renewable energy sources, and releases no carbon dioxide emissions into the atmosphere.

  10. Collimating lens for light-emitting-diode light source based on non-imaging optics.

    Science.gov (United States)

    Wang, Guangzhen; Wang, Lili; Li, Fuli; Zhang, Gongjian

    2012-04-10

    A collimating lens for a light-emitting-diode (LED) light source is an essential device widely used in lighting engineering. Lens surfaces are calculated by geometrical optics and nonimaging optics. This design progress does not rely on any software optimization and any complex iterative process. This method can be used for any type of light source not only Lambertian. The theoretical model is based on point source. But the practical LED source has a certain size. So in the simulation, an LED chip whose size is 1 mm*1 mm is used to verify the feasibility of the model. The mean results show that the lenses have a very compact structure and good collimating performance. Efficiency is defined as the ratio of the flux in the illuminated plane to the flux from LED source without considering the lens material transmission. Just investigating the loss in the designed lens surfaces, the two types of lenses have high efficiencies of more than 90% and 99%, respectively. Most lighting area (possessing 80% flux) radii are no more than 5 m when the illuminated plane is 200 m away from the light source. PMID:22505154

  11. Bright artificial light subsensitizes a central muscarinic mechanism.

    Science.gov (United States)

    Dilsaver, S C; Majchrzak, M J

    1987-12-14

    Supersensitivity of a muscarinic mechanism is implicated in the pathophysiology of depression. Bright artificial light is efficacious in the treatment of Seasonal Affective Disorder (SAD). We studied the effect of constant bright light (11,500 lux) on the sensitivity of adult, male rats to oxotremorine, 1.5 mg/kg ip, using a repeated measures design. Oxotremorine challenges were proceeded by the injection of methylscopolamine, 1 mg/kg ip, by 30 minutes. Temperature was telemetrically measured every 10 minutes for 120 minutes starting 10 minutes after the injection of oxotremorine. Prior to and after 7 continuous days of exposure to bright light, the sample exhibited a hypothermic response of 2.50 +/- 0.48 degrees C (mean +/- SEM) and 0.29 +/- 0.31 degrees C (mean +/- SEM), respectively (p less than 0.0014). All 7 animals exhibited blunting to the thermic response to oxotremorine. Bright light also blocked the capacity of amitriptyline to supersensitize a central muscarinic mechanism. Exposure to light at an intensity of 300 lux for 7 days had no effect on the thermic response to oxotremorine. These data are consistent with the hypotheses that the biology of depression involves supersensitivity of central muscarinic mechanisms and that the effects of bright artificial light are not the consequence of shifting circadian rhythms. PMID:3695799

  12. Night Sky Brightness and Light Pollution in Comunidad de Madrid

    OpenAIRE

    Zamorano Calvo, Jaime; Sánchez de Miguel, Alejandro; Gómez Castaño, José; Ocaña González, Francisco; Gallego Maestro, Jesús; Pila Díez, Berenice; Nievas Rosillo, Miguel; Tapia Ayuga, Carlos; Fernández Domínguez, Alberto; Pascual Ramírez, Sergio

    2013-01-01

    Preliminary results of a study of the night sky background brightness around the city of Madrid using Sky Quality Meter (SQM) photometers are presented. Data-retrieval methodology includes an automatic procedure to measure from a moving vehicle which allows to speed up the data gathering. The night sky brightness, an astronomical quality parameter that accounts for luminous flux from the sky, is closely related with the light pollution. The map with the spatial distribution of the night s...

  13. Effects of Bright Light Treatment on Psychomotor Speed in Athletes

    Directory of Open Access Journals (Sweden)

    Mikko Paavo Tulppo

    2014-05-01

    Full Text Available Purpose: A recent study suggests that transcranial brain targeted light treatment via ear canals may have physiological effects on brain function studied by functional magnetic resonance imaging (fMRI techniques in humans. We tested the hypothesis that bright light treatment could improve psychomotor speed in professional ice hockey players. Methods: Psychomotor speed tests with audio and visual warning signals were administered to a Finnish National Ice Hockey League team before and after 24 days of transcranial bright light or sham treatment. The treatments were given during seasonal darkness in the Oulu region (latitude 65 degrees north when the strain on the players was also very high (10 matches during 24 days. A daily 12-min dose of bright light or sham (n = 11 for both treatment was given every morning between 8–12 am at home with a transcranial bright light device. Mean reaction time and motor time were analyzed separately for both psychomotor tests. Analysis of variance for repeated measures adjusted for age was performed. Results: Time x group interaction for motor time with a visual warning signal was p = 0.024 after adjustment for age. In Bonferroni post-hoc analysis, motor time with a visual warning signal decreased in the bright light treatment group from 127 ± 43 to 94 ± 26 ms (p = 0.024 but did not change significantly in the sham group 121 ± 23 vs. 110 ± 32 ms (p = 0.308. Reaction time with a visual signal did not change in either group. Reaction or motor time with an audio warning signal did not change in either the treatment or sham group. Conclusion: Psychomotor speed, particularly motor time with a visual warning signal, improves after transcranial bright light treatment in professional ice-hockey players during the competition season in the dark time of the year.

  14. Long-range visible light communication system based on LED collimating lens

    Science.gov (United States)

    Chen, Yingcong; Wen, Shangsheng; Wu, Yuxiang; Ren, Yuanyuan; Guan, Weipeng; Zhou, Yunlin

    2016-10-01

    An advanced visible light communication (VLC) system is proposed for long-range VLC, such as marine communication. The design of the system is conducted into two parts. Firstly, we design and optimize a collimating lens for the optical antenna by using Taguchi method. The lighting effects and optical power of the receiving end in different distances are simulated by TracePro software. Then, the long-range VLC channel is reconstructed by integrating the influence of the atmospheric attenuation and frequency response. The performance of the OOK coding VLC system is tested by Matlab software. The results show that: the emitting angle of the optimized collimating lens is 1.7°. By using 1 W LED and collimating lens as an optical antenna, the system can achieve a data rate of 210 Mbit/s at a bit error rate of 10-3 in 90 m.

  15. The "Brightness Rules" Alternative Conception for Light Bulb Circuits

    Science.gov (United States)

    Bryan, Joel A.; Stuessy, Carol

    2006-01-01

    An alternative conception for the observed differences in light bulb brightness was revealed during an unguided inquiry investigation in which prospective elementary teachers placed identical bulbs in series, parallel, and combination direct current circuits. Classroom observations, document analyses, and video and audio transcriptions led to the…

  16. Efficacy of a single sequence of intermittent bright light pulses for delaying circadian phase in humans. : Phase delaying efficacy of intermittent bright light

    OpenAIRE

    Gronfier, Claude; Wright, Kenneth,; Kronauer, Richard,; Jewett, Megan,; Czeisler, Charles,

    2004-01-01

    International audience It has been shown in animal studies that exposure to brief pulses of bright light can phase shift the circadian pacemaker and that the resetting action of light is most efficient during the first minutes of light exposure. In humans, multiple consecutive days of exposure to brief bright light pulses have been shown to phase shift the circadian pacemaker. The aim of the present study was to determine whether a single sequence of brief bright light pulses administered ...

  17. Human responses to bright light of different durations.

    Science.gov (United States)

    Chang, Anne-Marie; Santhi, Nayantara; St Hilaire, Melissa; Gronfier, Claude; Bradstreet, Dayna S; Duffy, Jeanne F; Lockley, Steven W; Kronauer, Richard E; Czeisler, Charles A

    2012-07-01

    Light exposure in the early night induces phase delays of the circadian rhythm in melatonin in humans. Previous studies have investigated the effect of timing, intensity, wavelength, history and pattern of light stimuli on the human circadian timing system. We present results from a study of the duration–response relationship to phase-delaying bright light. Thirty-nine young healthy participants (16 female; 22.18±3.62 years) completed a 9-day inpatient study. Following three baseline days, participants underwent an initial circadian phase assessment procedure in dim light (bright light pulse (∼10,000 lux) of 0.2 h, 1.0 h, 2.5 h or 4.0 h duration during a 4.5 h controlled-posture episode centred in a 16 h wake episode. After another 8 h sleep episode, participants completed a second circadian phase assessment. Phase shifts were calculated from the difference in the clock time of the dim light melatonin onset (DLMO) between the initial and final phase assessments. Exposure to varying durations of bright light reset the circadian pacemaker in a dose-dependent, non-linear manner. Per minute of exposure, the 0.2 h duration was over 5 times more effective at phase delaying the circadian pacemaker (1.07±0.36 h) as compared with the 4.0 h duration (2.65±0.24 h). Acute melatonin suppression and subjective sleepiness also had a dose-dependent response to light exposure duration. These results provide strong evidence for a non-linear resetting response of the human circadian pacemaker to light duration.

  18. Prophylactic treatment of seasonal affective disorder (SAD) by using light visors : Bright white or infrared light?

    NARCIS (Netherlands)

    Meesters, Y; Beersma, DGM; Bouhuys, AL; van den Hoofdakker, RH

    1999-01-01

    Background: Thirty-eight patients with SAD participated in a light visor study addressing two questions. 1. Can the development of a depressive episode be prevent ed by daily exposure to bright light started before symptom onset in early fall and continued throughout the winter? 2. Does the light ha

  19. Bright light treatment of depression for older adults [ISRCTN55452501

    Directory of Open Access Journals (Sweden)

    Knickerbocker Nancy C

    2005-11-01

    Full Text Available Abstract Background The incidence of insomnia and depression in the elder population is significant. It is hoped that use of light treatment for this group could provide safe, economic, and effective rapid recovery. Methods In this home-based trial we treated depressed elderly subjects with bright white (8,500 Lux and dim red ( Results Eighty-one volunteers, between 60 and 79 years old, completed the study. Both treatment and placebo groups experienced mood improvement. Average GDS scores improved 5 points, the Hamilton Depression Rating Scale (HDRS 17 scores (extracted from the self-rated SIGH-SAD-SR improved 6 points. There were no significant treatment effects or time-by-treatment interactions. No significant adverse reactions were observed in either treatment group. The assays of urine and saliva showed no significant differences between the treatment and placebo groups. The healthy control group was active earlier and slept earlier but received less light than the depressed group at baseline. Conclusion Antidepressant response to bright light treatment in this age group was not statistically superior to placebo. Both treatment and placebo groups experienced a clinically significant overall improvement of 16%.

  20. Highly Bright White Organic Light-Emitting Diode

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ A highly bright white organic light-emitting diode (OLED) was realized by using a highly bright blue emitting layer, 1,7-diphenyl-4-biphenyl-3,5-dimethyl-l,7-dihydrodipyrazolo[3,4-b;4',3'-e]pyridine (PAP-Ph), together with a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped Alq [tris(8-hydroxyquinolinato) aluminum (Ⅲ)] layer to provide the blue, red and green emission for color mixing. With appropriate thickness control, the white-light OLED has a performance that reaches 24700 cd/m2 at 15 V, 1.93 lm/W at 6.5 V, and >300 cd/m2 at 7.7 mA/em2. The Commission Internationale de l'Eclairage (CIE) coordinates of the emitted light vary in a very small range, from (0.35, 0.34) to (0.34, 0.35), when forward voltages change from 6 to 12 V.

  1. Highly Bright White Organic Light-Emitting Diode

    Institute of Scientific and Technical Information of China (English)

    KO; C.; W.

    2001-01-01

    A highly bright white organic light-emitting diode (OLED) was realized by using a highly bright blue emitting layer, 1,7-diphenyl-4-biphenyl-3,5-dimethyl-l,7-dihydrodipyrazolo[3,4-b;4',3'-e]pyridine (PAP-Ph), together with a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped Alq [tris(8-hydroxyquinolinato) aluminum (Ⅲ)] layer to provide the blue, red and green emission for color mixing. With appropriate thickness control, the white-light OLED has a performance that reaches 24700 cd/m2 at 15 V, 1.93 lm/W at 6.5 V, and >300 cd/m2 at 7.7 mA/em2. The Commission Internationale de l'Eclairage (CIE) coordinates of the emitted light vary in a very small range, from (0.35, 0.34) to (0.34, 0.35), when forward voltages change from 6 to 12 V.  ……

  2. Implementing bright light treatment for MSFC payload operations shiftworkers

    Science.gov (United States)

    Hayes, Benita C.; Stewart, Karen T.; Eastman, Charmane I.

    1994-01-01

    Intense light can phase-shift circadian rhythms and improve performance, sleep, and wellbeing during shiftwork simulations, but to date there have been very few attempts to administer light treatment to real shiftworkers. We have developed procedures for implementing light treatment and have conducted controlled trials of light treatment for MSFC Payload Operations staff during the USML-1 mission. We found that treatment had beneficial effects on fatigue, alertness, self-rated job performance, sleep, mood, and work attendance. Although there are portable bright light boxes commercially available, there is no testing protocol and little performance information available. We measure the illuminance of two candidate boxes for use in this study and found that levels were consistently lower than those advertised by manufacturers. A device was developed to enhance the illuminance output of such units. This device increased the illuminance by at least 60 % and provided additional improvements in visual comfort and overall exposure. Both the design of this device and some suggested procedures for evaluating light devices are presented.

  3. Relationships between brightness of nighttime lights and population density

    Science.gov (United States)

    Naizhuo, Z.

    2012-12-01

    Brightness of nighttime lights has been proven to be a good proxy for socioeconomic and demographic statistics. Moreover, the satellite nighttime lights data have been used to spatially disaggregate amounts of gross domestic product (GDP), fossil fuel carbon dioxide emission, and electric power consumption (Ghosh et al., 2010; Oda and Maksyutov, 2011; Zhao et al., 2012). Spatial disaggregations were performed in these previous studies based on assumed linear relationships between digital number (DN) value of pixels in the nighttime light images and socioeconomic data. However, reliability of the linear relationships was never tested due to lack of relative high-spatial-resolution (equal to or finer than 1 km × 1 km) statistical data. With the similar assumption that brightness linearly correlates to population, Bharti et al. (2011) used nighttime light data as a proxy for population density and then developed a model about seasonal fluctuations of measles in West Africa. The Oak Ridge National Laboratory used sub-national census population data and high spatial resolution remotely-sensed-images to produce LandScan population raster datasets. The LandScan population datasets have 1 km × 1 km spatial resolution which is consistent with the spatial resolution of the nighttime light images. Therefore, in this study I selected 2008 LandScan population data as baseline reference data and the contiguous United State as study area. Relationships between DN value of pixels in the 2008 Defense Meteorological Satellite Program's Operational Linescan System (DMSP-OLS) stable light image and population density were established. Results showed that an exponential function can more accurately reflect the relationship between luminosity and population density than a linear function. Additionally, a certain number of saturated pixels with DN value of 63 exist in urban core areas. If directly using the exponential function to estimate the population density for the whole brightly

  4. Efficacy of a single sequence of intermittent bright light pulses for delaying circadian phase in humans

    OpenAIRE

    Gronfier, Claude; Wright, Kenneth P.; Kronauer, Richard E.; Jewett, Megan E.; Czeisler, Charles A.

    2004-01-01

    It has been shown in animal studies that exposure to brief pulses of bright light can phase shift the circadian pacemaker, and that the resetting action of light is most efficient during the first minutes of light exposure. In humans, multiple consecutive days of exposure to brief bright light pulses have been shown to phase shift the circadian pacemaker. The aim of the present study was to determine if a single sequence of brief bright light pulses administered during the early biological ni...

  5. Reduction of human sleep duration after bright light exposure in the morning

    NARCIS (Netherlands)

    Dijk, D.J.; Visscher, C.A.; Bloem, G.M.; Beersma, D.G.M.; Daan, S.

    1987-01-01

    In 8 subjects the spontaneous termination of sleep was determined after repetitive exposure to either bright or dim light, between 6:00 and 9:00 h, on 3 days preceding sleep assessment. Sleep duration was significantly shorter following bright light than following dim light. During sleep the time co

  6. Bright light in elderly subjects with nonseasonal major depressive disorder: a double blind randomised clinical trial using early morning bright blue light comparing dim red light treatment

    Directory of Open Access Journals (Sweden)

    van Someren Eus JW

    2008-07-01

    Full Text Available Abstract Background Depression frequently occurs in the elderly. Its cause is largely unknown, but several studies point to disturbances of biological rhythmicity. In both normal aging, and depression, the functioning of the suprachiasmatic nucleus (SCN is impaired, as evidenced by an increased prevalence of day-night rhythm perturbations, such as sleeping disorders. Moreover, the inhibitory SCN neurons on the hypothalamus-pituitary adrenocortical axis (HPA-axis have decreased activity and HPA-activity is enhanced, when compared to non-depressed elderly. Using bright light therapy (BLT the SCN can be stimulated. In addition, the beneficial effects of BLT on seasonal depression are well accepted. BLT is a potentially safe, nonexpensive and well accepted treatment option. But the current literature on BLT for depression is inconclusive. Methods/Design This study aims to show whether BLT can reduce non-seasonal major depression in elderly patients. Randomized double blind placebo controlled trial in 126 subjects of 60 years and older with a diagnosis of major depressive disorder (MDD, DSM-IV/SCID-I. Subjects are recruited through referrals of psychiatric outpatient clinics and from case finding from databases of general practitioners and old-people homes in the Amsterdam region. After inclusion subjects are randomly allocated to the active (bright blue light vs. placebo (dim red light condition using two Philips Bright Light Energy boxes type HF 3304 per subject, from which the light bulbs have been covered with bright blue- or dim red light- permitting filters. Patients will be stratified by use of antidepressants. Prior to treatment a one-week period without light treatment will be used. At three time points several endocrinological, psychophysiological, psychometrically, neuropsychological measures are performed: just before the start of light therapy, after completion of three weeks therapy period, and three weeks thereafter. Discussion If BLT

  7. Pioneer 10 observations of zodiacal light brightness near the ecliptic - Changes with heliocentric distance

    Science.gov (United States)

    Hanner, M. S.; Weinberg, J. L.; Beeson, D. E.; Sparrow, J. G.

    1976-01-01

    Sky maps made by the Pioneer 10 Imaging Photopolarimeter (IPP) at sun-spacecraft distances from 1 to 3 AU have been analyzed to derive the brightness of the zodiacal light near the ecliptic at elongations greater than 90 degrees. The change in zodiacal light brightness with heliocentric distance is compared with models of the spatial distribution of the dust. Use of background starlight brightnesses derived from IPP measurements beyond the asteroid belt, where the zodiacal light is not detected, and, especially, use of a corrected calibration lead to considerably lower values for zodiacal light than those reported by us previously.

  8. Bending self-collimated one-way light by using gyromagnetic photonic crystals

    International Nuclear Information System (INIS)

    We theoretically demonstrate that electromagnetic waves can self-collimate and propagate unidirectionally in photonic crystals fabricated using semicylindrical ferrite rods in magnetized states. The parity and time-reversal symmetries of such photonic crystals are broken, resulting in a self-collimated one-way body wave within the photonic crystals. By applying the bias magnetic field in a complex configuration, the self-collimated one-way wave beam can be bent into arbitrary trajectories within the photonic crystal, providing an avenue for controlling wave beams

  9. Bending self-collimated one-way light by using gyromagnetic photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qing-Bo [School of Electronic Sciences and Engineering, Nanjing University, Nanjing 210093 (China); Jiangsu Key Construction Laboratory of Modern Measurement Technology and Intelligent System, Huaiyin Normal University, Huaian 223300 (China); Li, Zhen; Wu, Rui-xin, E-mail: rxwu@nju.edu.cn [School of Electronic Sciences and Engineering, Nanjing University, Nanjing 210093 (China)

    2015-12-14

    We theoretically demonstrate that electromagnetic waves can self-collimate and propagate unidirectionally in photonic crystals fabricated using semicylindrical ferrite rods in magnetized states. The parity and time-reversal symmetries of such photonic crystals are broken, resulting in a self-collimated one-way body wave within the photonic crystals. By applying the bias magnetic field in a complex configuration, the self-collimated one-way wave beam can be bent into arbitrary trajectories within the photonic crystal, providing an avenue for controlling wave beams.

  10. Regulation of lipid peroxidation in the retina under the effect of bright light.

    Science.gov (United States)

    Dzhafarov, A I; Kasimov, E M; Mamedov, Sh Y

    2011-04-01

    Changes in LPO intensity under the effect of exposure to bright light and the possibility of their correction with antioxidants were studied on rabbits with diabetic retinopathy. It was found that enhanced LPO caused by exposure to bright light in rabbits with diabetic retinopathy can be corrected with antioxidants. Phenosan potassium salt, α-tocopherol, and oxypyridine were more effective than SOD and taurine in preventing MDA accumulation. A complex of natural and synthetic antioxidants was most efficient in correcting LPO under conditions of exposure to bright light.

  11. Regulation of lipid peroxidation in the retina under the effect of bright light.

    Science.gov (United States)

    Dzhafarov, A I; Kasimov, E M; Mamedov, Sh Y

    2011-04-01

    Changes in LPO intensity under the effect of exposure to bright light and the possibility of their correction with antioxidants were studied on rabbits with diabetic retinopathy. It was found that enhanced LPO caused by exposure to bright light in rabbits with diabetic retinopathy can be corrected with antioxidants. Phenosan potassium salt, α-tocopherol, and oxypyridine were more effective than SOD and taurine in preventing MDA accumulation. A complex of natural and synthetic antioxidants was most efficient in correcting LPO under conditions of exposure to bright light. PMID:22235421

  12. Compact stacking of diode lasers for pulsed light sources of high brightness.

    Science.gov (United States)

    Alahautala, Taito; Lassila, Erkki; Hernberg, Rolf

    2004-07-20

    A compact stacking architecture for high-power diode-laser arrays is proposed and compared with traditional stacks. The objective of compact stacking is to achieve high brightness values without the use of microlenses. The calculated brightness for a compact stack is over 300 W mm(-2) sr(-1), which is approximately 40 times higher than that of a traditional stack made of similar laser emitters. Even higher brightness values of over 600 W mm(-2) sr(-1) were reached in practice. A laser head was manufactured in which the light from several compact laser stacks could be fiber coupled or the light could be transformed to a highly uniform beam.

  13. Artificial light alters natural regimes of night-time sky brightness

    Science.gov (United States)

    Davies, Thomas W.; Bennie, Jonathan; Inger, Richard; Gaston, Kevin J.

    2013-04-01

    Artificial light is globally one of the most widely distributed forms of anthropogenic pollution. However, while both the nature and ecological effects of direct artificial lighting are increasingly well documented, those of artificial sky glow have received little attention. We investigated how city lights alter natural regimes of lunar sky brightness using a novel ten month time series of measurements recorded across a gradient of increasing light pollution. In the city, artificial lights increased sky brightness to levels six times above those recorded in rural locations, nine and twenty kilometers away. Artificial lighting masked natural monthly and seasonal regimes of lunar sky brightness in the city, and increased the number and annual regime of full moon equivalent hours available to organisms during the night. The changes have potentially profound ecological consequences.

  14. Bright light exposure reduces TH-positive dopamine neurons: implications of light pollution in Parkinson's disease epidemiology

    OpenAIRE

    Romeo, Stefania; Viaggi, Cristina; Di Camillo, Daniela; Willis, Allison W.; Lozzi, Luca; Rocchi, Cristina; Capannolo, Marta; Aloisi, Gabriella; Vaglini, Francesca; Maccarone, Rita; Caleo, Matteo; Missale, Cristina; Racette, Brad A.; Corsini, Giovanni U.; Maggio, Roberto

    2013-01-01

    This study explores the effect of continuous exposure to bright light on neuromelanin formation and dopamine neuron survival in the substantia nigra. Twenty-one days after birth, Sprague–Dawley albino rats were divided into groups and raised under different conditions of light exposure. At the end of the irradiation period, rats were sacrificed and assayed for neuromelanin formation and number of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra. The rats exposed to bright li...

  15. Artificial light alters natural regimes of night-time sky brightness

    OpenAIRE

    Davies, Thomas W.; Bennie, Jonathan; Inger, Richard; Gaston, Kevin J.

    2013-01-01

    Artificial light is globally one of the most widely distributed forms of anthropogenic pollution. However, while both the nature and ecological effects of direct artificial lighting are increasingly well documented, those of artificial sky glow have received little attention. We investigated how city lights alter natural regimes of lunar sky brightness using a novel ten month time series of measurements recorded across a gradient of increasing light pollution. In the city, artificial lights i...

  16. Design of collimating system for LED source

    Science.gov (United States)

    Shen, Yanan; Huang, Yifan; Xing, Han

    2013-12-01

    Along with the development of semiconductor lighting technology, LED chip is widely used as the source of the glare flashlight. Collimating the light of the source and improving the utilization rate of light energy is crucial. The collimating lens is designed by the theory of geometrical optics and the theory of non-imaging optics. The small angle light from the source is collimated through the collimating lens surface, and the large angle light is collimated by the total reflection of the collimating lens. The collimating lens has a high light energy utilization and a good collimating performance. The collimation system is simulated and optimized in the Lighttools software. When the size of the LED chip is 1 mm*1 mm, the energy utilization rate of the collimating lens is more than 95%, and most lighting area radii are no more than 8 m when the illuminated plane is 500 m away from the light source.

  17. Bright green light treatment of depression for older adults [ISRCTN69400161

    Directory of Open Access Journals (Sweden)

    Knickerbocker Nancy C

    2005-11-01

    Full Text Available Abstract Background Bright white light has been successfully used for the treatment of depression. There is interest in identifying which spectral colors of light are the most efficient in the treatment of depression. It is theorized that green light could decrease the intensity duration of exposure needed. Late Wake Treatment (LWT, sleep deprivation for the last half of one night, is associated with rapid mood improvement which has been sustained by light treatment. Because spectral responsiveness may differ by age, we examined whether green light would provide efficient antidepressant treatment in an elder age group. Methods We contrasted one hour of bright green light (1,200 Lux and one hour of dim red light placebo ( Results The protocol was completed by 33 subjects who were 59 to 80 years old. Mood improved on average 23% for all subjects, but there were no significant statistical differences between treatment and placebo groups. There were negligible adverse reactions to the bright green light, which was well tolerated. Conclusion Bright green light was not shown to have an antidepressant effect in the age group of this study, but a larger trial with brighter green light might be of value.

  18. Unconditional generation of bright coherent non-Gaussian light from exciton-polariton condensates

    OpenAIRE

    Byrnes, Tim; Yamamoto, Yoshihisa; van Loock, Peter

    2012-01-01

    Exciton-polariton condensates are considered as a deterministic source of bright, coherent non-Gaussian light. Exciton-polariton condensates emit coherent light via the photoluminescence through the microcavity mirrors due to the spontaneous formation of coherence. Unlike conventional lasers which emit coherent Gaussian light, polaritons possess a natural nonlinearity due to the interaction of the excitonic component. This produces light with a negative component to the Wigner function at ste...

  19. Bright green light treatment of depression for older adults [ISRCTN69400161

    OpenAIRE

    Knickerbocker Nancy C; Kripke Daniel F; Loving Richard T; Grandner Michael A

    2005-01-01

    Abstract Background Bright white light has been successfully used for the treatment of depression. There is interest in identifying which spectral colors of light are the most efficient in the treatment of depression. It is theorized that green light could decrease the intensity duration of exposure needed. Late Wake Treatment (LWT), sleep deprivation for the last half of one night, is associated with rapid mood improvement which has been sustained by light treatment. Because spectral respons...

  20. Near-field collimation of light carrying orbital angular momentum with bull’s-eye-assisted plasmonic coaxial waveguides

    Science.gov (United States)

    Pu, Mingbo; Ma, Xiaoliang; Zhao, Zeyu; Li, Xiong; Wang, Yanqin; Gao, Hui; Hu, Chenggang; Gao, Ping; Wang, Changtao; Luo, Xiangang

    2015-01-01

    The orbital angular momentum (OAM) of light, as an emerging hotspot in optics and photonics, introduces many degrees of freedom for applications ranging from optical communication and quantum processing to micromanipulation. To achieve a high degree of integration, optical circuits for OAM light are essential, which are, however, challenging in the optical regime owing to the lack of well-developed theory. Here we provide a scheme to guide and collimate the OAM beam at the micro- and nano-levels. The coaxial plasmonic slit was exploited as a naturally occurring waveguide for light carrying OAM. Concentric grooves etched on the output surface of the coaxial waveguide were utilized as a plasmonic metasurface to couple the OAM beam to free space with greatly increased beam directivity. Experimental results at λ = 532 nm validated the novel transportation and collimating effect of the OAM beam. Furthermore, dynamic tuning of the topological charges was demonstrated by using a liquid crystal spatial light modulator (SLM). PMID:26159423

  1. Light Harvesting as a Simple and Versatile Way to Enhance Brightness of Luminescent Sensors

    OpenAIRE

    Mayr, Torsten; Borisov, Sergey M; Abel, Tobias; Enko, Barbara; Waich, Kerstin; Mistlberger, Günter; Klimant, Ingo

    2009-01-01

    The emissive output of indicator dyes in luminescent sensors can be amplified by the addition of antenna dyes with a higher brightness. The highly concentrated antenna dye molecules absorb the excitation light and transfer the energy to an indicator dye. This harvesting of light makes thin sensor layers (thickness

  2. The Stimulating Effect of Bright Light on Physical Performance Depends on Internal Time

    NARCIS (Netherlands)

    Kantermann, Thomas; Forstner, Sebastian; Halle, Martin; Schlangen, Luc; Roenneberg, Till; Schmidt-Trucksaess, Arno

    2012-01-01

    The human circadian clock regulates the daily timing of sleep, alertness and performance and is synchronized to the 24-h day by the environmental light-dark cycle. Bright light exposure has been shown to positively affect sleepiness and alertness, yet little is known about its effects on physical pe

  3. Spatial Filtering Versus Anchoring Accounts of Brightness/Lightness Perception in Staircase and Simultaneous Brightness/Lightness Contrast Stimuli

    OpenAIRE

    Blakeslee, Barbara; Reetz, Daniel; McCourt, Mark E.

    2009-01-01

    Cataliotti and Gilchrist (1995) reported that, consistent with anchoring theory, the lightness of a black step in a reflectance staircase was not altered by moving a white step from a remote to an adjacent location. Recently, Economou, Zdravkovic and Gilchrist (2007) reported data supporting three additional predictions of the anchoring model (Gilchrist et al., 1999): 1) equiluminant incremental targets in staircase simultaneous lightness contrast stimuli appeared equally light; 2) the simult...

  4. Bright Light-Emitting Diodes Based on Organometal Halide Perovskite Nanoplatelets.

    Science.gov (United States)

    Ling, Yichuan; Yuan, Zhao; Tian, Yu; Wang, Xi; Wang, Jamie C; Xin, Yan; Hanson, Kenneth; Ma, Biwu; Gao, Hanwei

    2016-01-13

    Bright light-emitting diodes based on solution-processable organometal halide perovskite nanoplatelets are demonstrated. The nanoplatelets created using a facile one-pot synthesis exhibit narrow-band emissions at 529 nm and quantum yield up to 85%. Using these nanoparticles as emitters, efficient electroluminescence is achieved with a brightness of 10 590 cd m(-2) . These ligand-capped nanoplatelets appear to be quite stable in moisture, allowing out-of-glovebox device fabrication.

  5. Beam collimator

    CERN Multimedia

    1977-01-01

    A four-block collimator installed on a control table for positioning the alignment reference marks. Designed for use with SPS secondary beams, the collimator operates under vacuum conditions. See Annual Report 1976 p. 121 and photo 7701014.

  6. Volume-scalable high-brightness three-dimensional visible light source

    Science.gov (United States)

    Subramania, Ganapathi; Fischer, Arthur J; Wang, George T; Li, Qiming

    2014-02-18

    A volume-scalable, high-brightness, electrically driven visible light source comprises a three-dimensional photonic crystal (3DPC) comprising one or more direct bandgap semiconductors. The improved light emission performance of the invention is achieved based on the enhancement of radiative emission of light emitters placed inside a 3DPC due to the strong modification of the photonic density-of-states engendered by the 3DPC.

  7. Phosphorescent organic light emitting diodes with high efficiency and brightness

    Science.gov (United States)

    Forrest, Stephen R; Zhang, Yifan

    2015-11-12

    An organic light emitting device including a) an anode; b) a cathode; and c) an emissive layer disposed between the anode and the cathode, the emissive layer comprising an organic host compound and a phosphorescent compound exhibiting a Stokes Shift overlap greater than 0.3 eV. The organic light emitting device may further include a hole transport layer disposed between the emissive layer and the anode; and an electron transport layer disposed between the emissive layer and the cathode. In some embodiments, the phosphorescent compound exhibits a phosphorescent lifetime of less than 10 .mu.s. In some embodiments, the concentration of the phosphorescent compound ranges from 0.5 wt. % to 10 wt. %.

  8. Recognising faces: effects of lighting direction, inversion, and brightness reversal.

    Science.gov (United States)

    Johnston, Alan; Hill, Harold; Carman, Nicole

    2013-01-01

    When information about three-dimensional shape obtained from shading and shadows is ambiguous, the visual system favours an interpretation of surface geometry which is consistent with illumination from above. If pictures of top-lit faces are rotated the resulting stimulus is both figurally inverted and illuminated from below. In this study the question of whether the effects of figural inversion and lighting orientation on face recognition are independent or interactive is addressed. Although there was a clear inversion effect for faces illuminated from the front and above, the inversion effect was found to be reduced or eliminated for faces illuminated from below. A strong inversion effect for photographic negatives was also found but in this case the effect was not dependent on the direction of illumination. These findings are interpreted as evidence to suggest that lighting faces from below disrupts the formation of surface-based representations of facial shape. PMID:24601034

  9. Contributions of artificial lighting sources on light pollution in Hong Kong measured through a night sky brightness monitoring network

    CERN Document Server

    Pun, Chun Shing Jason; Leung, Wai Yan; Wong, Chung Fai

    2014-01-01

    Light pollution is a form of environmental degradation in which excessive artificial outdoor lighting, such as street lamps, neon signs, and illuminated signboards, affects the natural environment and the ecosystem. Poorly designed outdoor lighting not only wastes energy, money, and valuable Earth resources, but also robs us of our beautiful night sky. Effects of light pollution on the night sky can be evaluated by the skyglow caused by these artificial lighting sources, through measurements of the night sky brightness (NSB). The Hong Kong Night Sky Brightness Monitoring Network (NSN) was established to monitor in detail the conditions of light pollution in Hong Kong. Monitoring stations were set up throughout the city covering a wide range of urban and rural settings to continuously measure the variations of the NSB. Over 4.6 million night sky measurements were collected from 18 distinct locations between May 2010 and March 2013. This huge dataset, over two thousand times larger than our previous survey, for...

  10. Homogeneously Bright, Flexible, and Foldable Lighting Devices with Functionalized Graphene Electrodes.

    Science.gov (United States)

    Torres Alonso, Elias; Karkera, George; Jones, Gareth F; Craciun, Monica F; Russo, Saverio

    2016-07-01

    Alternating current electroluminescent technology allows the fabrication of large area, flat and flexible lights. Presently the maximum size of a continuous panel is limited by the high resistivity of available transparent electrode materials causing a visible gradient of brightness. Here, we demonstrate that the use of the best known transparent conductor FeCl3-intercalated few-layer graphene boosts the brightness of electroluminescent devices by 49% compared to pristine graphene. Intensity gradients observed for high aspect ratio devices are undetectable when using these highly conductive electrodes. Flat lights on polymer substrates are found to be resilient to repeated and flexural strains. PMID:27299371

  11. Bright-light intervention induces a dose-dependent increase in striatal response to risk in healthy volunteers

    DEFF Research Database (Denmark)

    Macoveanu, Julian; Fisher, Patrick M; Madsen, Martin K;

    2016-01-01

    function, for instance on risk taking, a process affected in depressive disorders. Here we examined the modulatory effects of bright-light exposure on brain activity during a risk-taking task. Thirty-two healthy male volunteers living in the greater Copenhagen area received 3weeks of bright...... the intervention modifies risk-taking related neural activity during a two-choice gambling task. We also assessed whether inter-individual differences in the serotonin transporter-linked polymorphic region (5-HTTLPR) genotype influenced the effects of bright-light intervention on risk processing. Bright......-light intervention led to a dose-dependent increase in risk-taking in the LA/LA group relative to the non-LA/LA group. Further, bright-light intervention enhanced risk-related activity in ventral striatum and head of caudate nucleus in proportion with the individual bright-light dose. The augmentation effect...

  12. Skylab experiment SO73: Gegenschein/zodiacal light. [electrophotometry of surface brightness and polarization

    Science.gov (United States)

    Weinberg, J. L.

    1976-01-01

    A 10 color photoelectric polarimeter was used to measure the surface brightness and polarization associated with zodiacal light, background starlight, and spacecraft corona during each of the Skylab missions. Fixed position and sky scanning observations were obtained during Skylab missions SL-2 and SL-3 at 10 wavelenghts between 4000A and 8200A. Initial results from the fixed-position data are presented on the spacecraft corona and on the polarized brightness of the zodiacal light. Included among the fixed position regions that were observed are the north celestial pole, south ecliptic pole, two regions near the north galactic pole, and 90 deg from the sun in the ecliptic. The polarized brightness of the zodiacal light was found to have the color of the sun at each of these positions. Because previous observations found the total brightness to have the color of the sun from the near ultraviolet out to 2.4 micrometers, the degree of polarization of the zodiacal light is independent of wavelength from 4000A to 8200A.

  13. Recognizing emotions in faces : effects of acute tryptophan depletion and bright light

    NARCIS (Netherlands)

    aan het Rot, Marije; Coupland, Nicholas; Boivin, Diane B.; Benkelfat, Chawki; Young, Simon N.

    2010-01-01

    In healthy never-depressed individuals, acute tryptophan depletion (ATD) may selectively decrease the accurate recognition of fearful facial expressions. Here we investigated the perception of facial emotions after ATD in more detail. We also investigated whether bright light, which can reverse ATD'

  14. High cortisol awakening response is associated with an impairment of the effect of bright light therapy

    DEFF Research Database (Denmark)

    Martiny, Klaus Per Juul; Lunde, Marianne Anita; Undén, M;

    2009-01-01

    OBJECTIVE: We investigated the predictive validity of the cortisol awakening response (CAR) in patients with non-seasonal major depression. METHOD: Patients were treated with sertraline in combination with bright or dim light therapy for a 5-week period. Saliva cortisol levels were measured in 63...

  15. Low-intensity treadmill exercise and/or bright light promote neurogenesis in adult rat brain

    Institute of Scientific and Technical Information of China (English)

    Sung Jin Kwon; Jeongsook Park; So Yun Park; Kwang Seop Song; Sun Tae Jung; So Bong Jung; Ik Ryeul Park; Wan Sung Choi; Sun Ok Kwon

    2013-01-01

    The hippocampus is a brain region responsible for learning and memory functions. The purpose of this study was to investigate the effects of low-intensity exercise and bright light exposure on neurogenesis and brain-derived neurotrophic factor expression in adult rat hippocampus. Male Sprague-Dawley rats were randomly assigned to control, exercise, light, or exercise + light groups (n = 9 per group). The rats in the exercise group were subjected to treadmill exercise (5 days per week, 30 minutes per day, over a 4-week period), the light group rats were irradiated (5 days per week, 30 minutes per day, 10 000 lx, over a 4-week period), the exercise + light group rats were subjected to treadmill exercise in combination with bright light exposure, and the control group rats remained sedentary over a 4-week period. Compared with the control group, there was a significant increase in neurogenesis in the hippocampal dentate gyrus of rats in the exercise, light, and exercise + light groups. Moreover, the expression level of brain-derived neurotrophic factor in the rat hippocampal dentate gyrus was significantly higher in the exercise group and light group than that in the control group. Interestingly, there was no significant difference in brain-derived neurotrophic factor expression between the control group and exercise + light group. These results indicate that low-intensity treadmill exercise (first 5 minutes at a speed of 2 m/min, second 5 minutes at a speed of 5 m/min, and the last 20 minutes at a speed of 8 m/min) or bright-light exposure therapy induces positive biochemical changes in the brain. In view of these findings, we propose that moderate exercise or exposure to sunlight during childhood can be beneficial for neural development.

  16. Night-sky brightness monitoring in Hong Kong - a city-wide light pollution assessment

    CERN Document Server

    Pun, Chun Shing Jason

    2011-01-01

    Results of the first comprehensive light pollution survey in Hong Kong are presented. The night-sky brightness was measured and monitored around the city using a portable light sensing device called the Sky Quality Meter over a 15-month period beginning in March 2008. A total of 1,957 data sets were taken at 199 distinct locations, including urban and rural sites covering all 18 Administrative Districts of Hong Kong. The survey shows that the environmental light pollution problem in Hong Kong is severe - the urban night-skies (sky brightness at 15.0 mag per arcsec square) are on average ~100 times brighter than at the darkest rural sites (20.1 mag per arcsec square), indicating that the high lighting densities in the densely populated residential and commercial areas lead to light pollution. In the worst polluted urban location studied, the night-sky at 13.2 mag per arcsec square can be over 500 times brighter than the darkest sites in Hong Kong. The observed night-sky brightness is found to be affected by hu...

  17. Enhancing the brightness of Si nanocrystal light-emitting devices with electro-excited surface plasmons

    Science.gov (United States)

    Chen, Jia-Rong; Zhou, Zhi-Quan; Hao, Hong-Chen; Lu, Ming

    2014-09-01

    The use of electro-excited surface plasmons (SPs) in Ag nanoparticles (Ag-NPs) is shown to enhance the brightness of Si nanocrystal light-emitting devices (Si-NC LEDs). The Ag-NPs are prepared on the Si-NC thin film by ultrasonic irradiation and postannealing treatments. Electro-excited SPs on Ag-NPs are found, which are induced by electron impact on Ag-NPs and the front electrode Al layer during the charge injection process of LED. The electro-excited SPs enhance the electroluminescence of Si-NC, or LED brightness, via the SP field coupling to the exciton dipole moment of Si-NC. A maximal 5.2-fold brightness enhancement of Si-NC LED is achieved at the postannealing temperature of 200 °C. Remnant far-field radiations arising from electro-excited SPs are detected, which further supports the existence of such SPs.

  18. A compact high brightness laser synchrotron light source for medical applications

    International Nuclear Information System (INIS)

    The present high-brightness hard X-ray sources have been developed as third generation synchrotron light sources based on large high energy electron storage rings and magnetic undulators. Recently availability of compact terawatt lasers arouses a great interest in the use of lasers as undulators. The laser undulator concept makes it possible to construct an attractive compact synchrotron radiation source which has been proposed as a laser synchrotron light source. This paper proposes a compact laser synchrotron light source for mediacal applications, such as an intravenous coronary angiography and microbeam therapy

  19. Night-sky brightness monitoring in Hong Kong A city-wide light pollution assessment

    OpenAIRE

    Pun, CSJ; So, CW

    2012-01-01

    Results of the first comprehensive light pollution survey in Hong Kong are presented. The night-sky brightness was measured and monitored around the city using a portable light-sensing device called the Sky QualityMeter over a 15-month period beginning in March 2008. A total of 1,957 data sets were taken at 199 distinct locations, including urban and rural sites covering all 18 Administrative Districts of Hong Kong. The survey shows that the environmental light pollution problem in Hong Kong ...

  20. The acute side effects of bright light therapy: a placebo-controlled investigation.

    Directory of Open Access Journals (Sweden)

    Yevgeny Botanov

    Full Text Available Despite the emergence of numerous clinical and non-clinical applications of bright light therapy (LT in recent decades, the prevalence and severity of LT side effects have not yet been fully explicated. A few adverse LT effects-headache, eye strain, irritability, and nausea-have been consistently reported among depressed individuals and other psychiatric cohorts, but there exists little published evidence regarding LT side effects in non-clinical populations, who often undergo LT treatment of considerably briefer duration. Accordingly, in the present study we examined, in a randomized sample of healthy young adults, the acute side effects of exposure to a single 30-minute session of bright white light (10,000 lux versus dim red light (< 500 lux. Across a broad range of potential side effects, repeated-measures analyses of variance revealed no significant group-by-time (Pre, Post interactions. In other words, bright light exposure was not associated with a significantly higher incidence of any reported side effect than was the placebo control condition. Nevertheless, small but statistically significant increases in both eye strain and blurred vision were observed among both the LT and control groups. Overall, these results suggest that the relatively common occurrence of adverse side effects observed in the extant LT literature may not fully extend to non-clinical populations, especially for healthy young adults undergoing LT for a brief duration.

  1. Bright Light for Weight Loss: Results of a Controlled Crossover Trial

    Directory of Open Access Journals (Sweden)

    Konstantin V. Danilenko

    2013-02-01

    Full Text Available Objective: To investigate whether bright light treatment can reduce body mass in overweight subjects irrespective of their seasonal (= light dependence. Methods: A crossover, placebo-controlled, randomized clinical trial was performed between November and April in Novosibirsk, Russia (55° N. The trial comprised a 3-week in-home session of morning bright light treatment using a device of light-emitting diodes and a 3-week placebo session by means of a deactivated ion generator, separated by an off-protocol period of at least 23 days. The number of placebo and light sessions was matched with respect to season. Data were obtained from 34 overweight women, aged 20-54 years, 10 were seasonal-dependent according to the Seasonal Pattern Assessment Questionnaire. Weekly measures included body weight, percentage body fat by bioimpedancemetry, and subjective scores (appetite, mood, energy levels. Results: Motivation and expectation towards weight loss were similar for the two intervention sessions. With light, compared to the placebo session, weight did not reduce significantly, but percentage fat, fat mass, and appetite were significantly lower (average fat reduction 0.35 kg. The latter two results remained significant after excluding seasonal-dependent subjects from the analysis. Irrespective of the type of intervention, seasonal-dependent subjects had greater weight and fat mass changes during treatment (decline p 0.036 or between sessions (regain p 0.003. Photoperiod (p = 0.0041, air temperature to a lesser extent (p = 0.012, but not sunshine (p = 0.29 was associated with the weight change (greater weight reduction if the second session was in spring. Conclusion: Morning bright light treatment reduces body fat and appetite in overweight women and may be included in weight control programs.

  2. Demonstration of a bright and compact source of tripartite nonclassical light

    OpenAIRE

    Allevi, Alessia; Bondani, Maria; Paris, Matteo G. A.; Andreoni, Alessandra

    2008-01-01

    We experimentally demonstrate the nonclassical photon number correlations expected in tripartite continuous variable states obtained by parametric processes. Our scheme involves a single nonlinear crystal, where two interlinked parametric interactions take place simultaneously, and represents a bright and compact source of a sub-shot-noise tripartite light field. We analyze the effects of the pump intensities on the numbers of detected photons and on the amount of noise reduction in some deta...

  3. Green bright squeezed light from a cw periodically poled KTP second harmonic generator

    DEFF Research Database (Denmark)

    Andersen, Ulrik Lund; Buchhave, Preben

    2002-01-01

    We present the experimental observation of bright amplitude squeezed light from a singly resonant second harmonic generator (SHG) based on a periodically poled potassium titanyl phosphate (KTP) crystal. Contrary to conventional SHG, the interacting waves in this device couple efficiently using...... reduction is greater than what could be expected using normal birefringence phase matched KTP with the same experimental parameters. Excellent agreement between experiment and theory is found. (C)2002 Optical Society of America....

  4. A novel high-brightness broadband light-source technology from the VUV to the IR

    Science.gov (United States)

    Horne, Stephen; Smith, Don; Besen, Matthew; Partlow, Matthew; Stolyarov, Daniil; Zhu, Huiling; Holber, William

    2010-04-01

    A novel technology has been developed which enables high-brightness, broadband light output from the VUV to the IR spectral regions. A focused laser is used to sustain a high-pressure xenon discharge inside a bulb, creating a smaller, hotter discharge than can be obtained by using an electrically-driven discharge. This allows for continuous output down to 120 nm wavelength and into the infrared. Application areas include hyperspectral imaging, standoff detection, surveillance, bioanalytical instrumentation, microscopy, and materials studies. Laser-driven optical discharges were first investigated over 30 years ago, providing the initial technical understanding of such discharges. However it took the convergence of two separate elements - the availability of low-cost, high-efficiency CW diode lasers; and a market need for high-brightness, broadband light source - to provide the impetus for further development in this area. Using near-IR CW diode lasers at power levels from 15 W to over 2000 W, we have generated high-pressure xenon discharges having temperatures as high as 10,000 C. The optical brightness of these discharges can be over an order of magnitude higher than those obtainable from the brightest xenon arc lamps, and can be several orders of magnitude brighter than deuterium lamps. Results from modeling of these discharges as well as experimental measurements will be presented.

  5. Determining contrast sensitivity functions for monochromatic light emitted by high-brightness LEDs

    Science.gov (United States)

    Ramamurthy, Vasudha; Narendran, Nadarajah; Freyssinier, Jean Paul; Raghavan, Ramesh; Boyce, Peter

    2004-01-01

    Light-emitting diode (LED) technology is becoming the choice for many lighting applications that require monochromatic light. However, one potential problem with LED-based lighting systems is uneven luminance patterns. Having a uniform luminance distribution is more important in some applications. One example where LEDs are becoming a viable alternative and luminance uniformity is an important criterion is backlighted monochromatic signage. The question is how much uniformity is required for these applications. Presently, there is no accepted metric that quantifies luminance uniformity. A recent publication proposed a method based on digital image analysis to quantify beam quality of reflectorized halogen lamps. To be able to employ such a technique to analyze colored beams generated by LED systems, it is necessary to have contrast sensitivity functions (CSFs) for monochromatic light produced by LEDs. Several factors including the luminance, visual field size, and spectral power distribution of the light affect the CSFs. Although CSFs exist for a variety of light sources at visual fields ranging from 2 degrees to 20 degrees, CSFs do not exist for red, green, and blue light produced by high-brightness LEDs at 2-degree and 10-degree visual fields and at luminances typical for backlighted signage. Therefore, the goal of the study was to develop a family of CSFs for 2-degree and 10-degree visual fields illuminated by narrow-band LEDs at typical luminances seen in backlighted signs. The details of the experiment and the results are presented in this manuscript.

  6. Time-of-day-dependent effects of bright light exposure on human psychophysiology : comparison of daytime and nighttime exposure

    NARCIS (Netherlands)

    Ruger, M; Gordijn, MCM; Beersma, DGM; de Vries, B; Daan, S

    2006-01-01

    Bright light can influence human psychophysiology instantaneously by inducing endocrine ( suppression of melatonin, increasing cortisol levels), other physiological changes ( enhancement of core body temperature), and psychological changes ( reduction of sleepiness, increase of alertness). Its broad

  7. Direct imaging of phase objects enables conventional deconvolution in bright field light microscopy.

    Directory of Open Access Journals (Sweden)

    Carmen Noemí Hernández Candia

    Full Text Available In transmitted optical microscopy, absorption structure and phase structure of the specimen determine the three-dimensional intensity distribution of the image. The elementary impulse responses of the bright field microscope therefore consist of separate absorptive and phase components, precluding general application of linear, conventional deconvolution processing methods to improve image contrast and resolution. However, conventional deconvolution can be applied in the case of pure phase (or pure absorptive objects if the corresponding phase (or absorptive impulse responses of the microscope are known. In this work, we present direct measurements of the phase point- and line-spread functions of a high-aperture microscope operating in transmitted bright field. Polystyrene nanoparticles and microtubules (biological polymer filaments serve as the pure phase point and line objects, respectively, that are imaged with high contrast and low noise using standard microscopy plus digital image processing. Our experimental results agree with a proposed model for the response functions, and confirm previous theoretical predictions. Finally, we use the measured phase point-spread function to apply conventional deconvolution on the bright field images of living, unstained bacteria, resulting in improved definition of cell boundaries and sub-cellular features. These developments demonstrate practical application of standard restoration methods to improve imaging of phase objects such as cells in transmitted light microscopy.

  8. Graded Heterojunction of AlGaInP High-brightness Light Emitting Diodes

    Institute of Scientific and Technical Information of China (English)

    LIU Lu; FAN Guang-han; LIAO Chang-jun

    2004-01-01

    A simple model of the graded heterojunction in AlGaInP compound semiconductors was introduced to analyze the band profile. The band profiles are analyzed with the different grading ways but the same grading length and under the different doping densities. The effect of the different grading lengths on the surplus of the potential of the spike to the potential of N region are also analyzed under the different doping densities.Through the experiments,it proves that the performances of high brightness light emitting diodes can be improved by the effects of the graded heterojunction.

  9. Growth of highly bright-white silica nanowires as diffusive reflection coating in LED lighting.

    Science.gov (United States)

    Xi, Shuang; Shi, Tielin; Zhang, Lei; Liu, Dan; Lai, Wuxing; Tang, Zirong

    2011-12-19

    Large quantities of silica nanowires were synthesized through thermal treatment of silicon wafer in the atmosphere of N(2)/H(2)(5%) under 1200 °C with Cu as catalyst. These nanowires grew to form a natural bright-white mat, which showed highly diffusive reflectivity over the UV-visible range, with more than 60% at the whole range and up to 88% at 350 nm. The utilization of silica nanowires in diffusive coating on the reflector cup of LED is demonstrated, which shows greatly improved light distribution comparing with the specular reflector cup. It is expected that these nanowires can be promising coating material for optoelectronic applications.

  10. Can light make us bright? Effects of light on cognition and sleep

    NARCIS (Netherlands)

    Chellappa, Sarah Laxhmi; Gordijn, Marijke C. M.; Cajochen, Christian; VanDongen, HPA; Kerkhof, GA

    2011-01-01

    Light elicits robust nonvisual effects on numerous physiological and behavioral variables, such as the human sleep-wake cycle and cognitive performance. Light effects crucially rely on properties such as dose, duration, timing, and wavelength. Recently, the use of methods such as fMRI to assess ligh

  11. Bright lights, big city: influences of ecological light pollution on reciprocal stream-riparian invertebrate fluxes.

    Science.gov (United States)

    Meyer, Lars A; Sullivan, S Mazeika P

    2013-09-01

    Cities produce considerable ecological light pollution (ELP), yet the effects of artificial night lighting on biological communities and ecosystem function have not been fully explored. From June 2010 to June 2011, we surveyed aquatic emergent insects, riparian arthropods entering the water, and riparian spiders of the family Tetragnathidae at nine stream reaches representing common ambient ELP levels of Columbus, Ohio, USA, streams (low, 0.1-0.5 lux; moderate, 0.6-2.0 lux; high, 2.1-4.0 lux). In August 2011, we experimentally increased light levels at the low- and moderate-treatment reaches to 10-12 lux to represent urban streams exposed to extremely high levels of ELP. Although season exerted the dominant influence on invertebrate fluxes over the course of the year, when analyzed by season, we found that light strongly influenced multiple invertebrate responses. The experimental light addition resulted in a 44% decrease in tetragnathid spider density (P = 0.035), decreases of 16% in family richness (P = 0.040) and 76% in mean body size (P = 0.022) of aquatic emergent insects, and a 309% increase in mean body size of terrestrial arthropods (P = 0.015). Our results provide evidence that artificial light sources can alter community structure and ecosystem function in streams via changes in reciprocal aquatic-terrestrial fluxes of invertebrates. PMID:24147405

  12. Light curve solutions for bright detached eclipsing binaries in SMC: absolute dimensions and distance indicators

    CERN Document Server

    Graczyk, D

    2003-01-01

    This paper presents a careful and detailed light curve analysis of bright detached eclipsing binaries (DEB) in the Small Magellanic Cloud, discovered by OGLE collaboration, on the basis of recently available difference image analysis (DIA) photometry. The 19 binaries brighter than 16.4 mag in I band and with the depth of primary and secondary eclipse greater than 0.25 mag were investigated. The solutions were obtained by a modified version of the Wilson-Devinney program. The quality of DIA light curves - a good phase coverage and relatively small scatter - is enough to calculate realistic estimates for the third light l_3 and the argument of periastron. It was found that solutions of detached, eccentric systems with flat light curve between eclipses usually may suffer from indetermination of l_3 in contrast to those of similar systems having some proximity effects. The physical properties of the stars were estimated on the basis of their photometric elements and indices assuming the distance modulus to SMC ~1...

  13. Bright Light Therapy in Parkinson's Disease: An Overview of the Background and Evidence

    Directory of Open Access Journals (Sweden)

    Sonja Rutten

    2012-01-01

    Full Text Available Sleep disorders are common in Parkinson's disease (PD and seem to be strongly associated with depression. It has been suggested that sleep disorders as well as depression are caused by a disturbed circadian rhythm. Indeed, PD patients are prone to misalignment of their circadian rhythm due to various factors, and many patients with PD display a phase advance of their circadian rhythm. Current treatment options for sleep disorders and depression in patients with PD are limited and can have serious side effects; alternative treatments are therefore badly needed. Bright light therapy (BLT restores circadian rhythmicity effectively in mood- and sleep-disturbed patients without PD. The few studies that focused on the efficacy of BLT in patients with PD demonstrated a positive effect of BLT not only on sleep and mood but also on motor function. More research on the neurobiology and efficacy of BLT in PD is warranted.

  14. Controlling an actively-quenched single photon detector with bright light.

    Science.gov (United States)

    Sauge, Sebastien; Lydersen, Lars; Anisimov, Andrey; Skaar, Johannes; Makarov, Vadim

    2011-11-01

    We control using bright light an actively-quenched avalanche single-photon detector. Actively-quenched detectors are commonly used for quantum key distribution (QKD) in the visible and near-infrared range. This study shows that these detectors are controllable by the same attack used to hack passively-quenched and gated detectors. This demonstrates the generality of our attack and its possible applicability to eavsdropping the full secret key of all QKD systems using avalanche photodiodes (APDs). Moreover, the commercial detector model we tested (PerkinElmer SPCM-AQR) exhibits two new blinding mechanisms in addition to the previously observed thermal blinding of the APD, namely: malfunctioning of the bias voltage control circuit, and overload of the DC/DC converter biasing the APD. These two new technical loopholes found just in one detector model suggest that this problem must be solved in general, by incorporating generally imperfect detectors into the security proof for QKD.

  15. Bright Ray-like Features in the Aftermath of CMEs: White Light vs UV Spectra

    CERN Document Server

    Ciaravella, A; Giordano, S; Raymond, J C

    2013-01-01

    Current sheets are important signatures of magnetic reconnection in the eruption of confined solar magnetic structures. Models of Coronal Mass Ejections (CMEs) involve formation of a current sheet connecting the ejected flux rope with the post eruption magnetic loops. Current sheets have been identified in white light images of CMEs as narrow rays trailing the outward moving CME core, and in ultraviolet spectra as narrow bright features emitting the Fe XVIII line. In this work samples of rays detected in white light images or in ultraviolet spectra have been analyzed. Temperatures, widths, and line intensities of the rays have been measured, and their correlation to the CME properties has been studied. The samples show a wide range of temperatures with hot, coronal and cool rays. In some cases, the UV spectra support the identification of rays as current sheets, but they show that some white light rays are cool material from the CME core. In many cases, both hot and cool material are present, but offset from ...

  16. Bright luminescence from pure DNA-curcumin–based phosphors for bio hybrid light-emitting diodes

    Science.gov (United States)

    Reddy, M. Siva Pratap; Park, Chinho

    2016-01-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s−1. Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign. PMID:27572113

  17. Bright luminescence from pure DNA-curcumin-based phosphors for bio hybrid light-emitting diodes.

    Science.gov (United States)

    Reddy, M Siva Pratap; Park, Chinho

    2016-01-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s(-1). Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign. PMID:27572113

  18. Bright luminescence from pure DNA-curcumin–based phosphors for bio hybrid light-emitting diodes

    Science.gov (United States)

    Reddy, M. Siva Pratap; Park, Chinho

    2016-08-01

    Recently, significant advances have occurred in the development of phosphors for bio hybrid light-emitting diodes (Bio-HLEDs), which have created brighter, metal-free, rare-earth phosphor-free, eco-friendly, and cost-competitive features for visible light emission. Here, we demonstrate an original approach using bioinspired phosphors in Bio-HLEDs based on natural deoxyribonucleic acid (DNA)-curcumin complexes with cetyltrimethylammonium (CTMA) in bio-crystalline form. The curcumin chromophore was bound to the DNA double helix structure as observed using field emission tunnelling electron microscopy (FE-TEM). Efficient luminescence occurred due to tightly bound curcumin chromophore to DNA duplex. Bio-HLED shows low luminous drop rate of 0.0551 s‑1. Moreover, the solid bio-crystals confined the activating bright luminescence with a quantum yield of 62%, thereby overcoming aggregation-induced quenching effect. The results of this study herald the development of commercially viable large-scale hybrid light applications that are environmentally benign.

  19. Three-dimensional spectrum mapping of bright emission centers: Investigating the brightness-limiting process in Eu-doped GaN red light emitting diodes

    International Nuclear Information System (INIS)

    A pulse-driven emission-spectroscopy mapping technique is used to investigate the bright emission centers in Eu-doped GaN (GaN:Eu) red light emitting diodes (LED). The LEDs are operated in pulse-driven mode, and the emission spectra are acquired for a range of pulse frequencies. This ensemble of emission spectral data yields a three-dimensional mapping that allows the origin of emission lines to be identified by visual inspection. The identification was achieved even for a weak 5D0 → 7F3 transition in conventional photoluminescence measurements. A peculiar split is observed in the 5D0 → 7F3 transition for the bright emission center referred to as OMVPE 8. Despite the unique transition at this emission center, the emission efficiencies for the 5D0 → 7F3 and 5D0 → 7F2 transitions were identical. This finding indicates that the excitation of the emission centers, rather than the radiative transitions, is the limiting process that determines the GaN:Eu red LED brightness

  20. Momentary adjusting methods for simulating the color temperature, hues and brightness of daylight illumination with RGB LEDs for indoor lighting.

    Science.gov (United States)

    Tsuei, Chih-Hsuan; Sun, Wen-Shing

    2011-07-01

    Methods for simulating the color temperature, hue and brightness of daylight illumination for indoor lighting simply by adjusting the intensity of red, green, and blue light emitting diodes are proposed. We obtain uniform color mixing with a light box by adjusting the ratios between the intensities of red, green and blue LEDs. The intensity can be found by measuring the CIE chromaticity coordinates (x, y) and the luminance Y of the daylight with a chroma meter. After the chromaticity coordinates (x, y) and the luminance Y are found, the tristimulus values can be calculated and then transferred to red, green, and blue primaries by linear transformation. With the correct ratio of red, green, and blue intensities, the color temperature, hues and brightness of daylight can be rebuilt by red, green, and blue light emitting diodes. PMID:21747561

  1. Doping in the Mixed Layer to Achieve High Brightness and Efficiency Organic Light Emitting Devices

    Institute of Scientific and Technical Information of China (English)

    高文宝; 杨开霞; 刘宏宇; 冯晶; 刘式墉

    2002-01-01

    Doping in the mixed layer was introduced to fabricate high brightness and high efficiency organic light emitting devices. In these devices, a copper phthalocyanine (CuPc) film acts as the buffer layer, a naphthylphenybiphenyl amine (NPB) film as the hole transport layer and a tris(8-hydroxyquinolinolate)aluminium (Alq3) film as the electron transport layer. The luminescent layer consists of the mixture of NPB, Alq3 (to be called the mixed layer), and an emitting dopant 5,6,11,12-petraphenylnaphthacene (rubrene), where the concentration of NPB declined and the concentration of Alq3 was increased gradually in the deposition process. Adopting this doping mixed layer, the device exhibits the maximum emission of 49300cd/m2 at 35 V and the maximum efficiency of 7.96cd/A at 10.5 V, which have been improved by two times in comparison with conventional doped devices. We attribute this improvement to the effective confinement of carriers in the mixed layer, which leads to the increase of the recombination efficiency of carriers.

  2. Influence of Type of Electric Bright Light on the Attraction of the African Giant Water Bug, Lethocerus indicus (Hemiptera: Belostomatidae

    Directory of Open Access Journals (Sweden)

    Luke Chinaru Nwosu

    2012-01-01

    Full Text Available This study investigated the influence of type of electric bright light (produced by fluorescent light tube and incandescent light bulb on the attraction of the African giant water bug, Lethocerus indicus (Hemiptera: Belostomatidae. Four fluorescent light tubes of 15 watts each, producing white-coloured light and four incandescent light bulbs of 60 watts each, producing yellow-coloured light, but both producing the same amount of light, were varied and used for the experiments. Collections of bugs at experimental house were done at night between the hours of 8.30 pm and 12 mid-night on daily basis for a period of four months per experiment in the years 2008 and 2009. Lethocerus indicus whose presence in any environment has certain implications was the predominant belostomatid bug in the area. Use of incandescent light bulbs in 2009 significantly attracted more Lethocerus indicus 103 (74.6% than use of fluorescent light tubes 35 (25.41% in 2008 [4.92=0.0001]. However, bug’s attraction to light source was not found sex dependent [>0.05; (>0.18=0.4286 and >0.28=0.3897]. Therefore, this study recommends the use of fluorescent light by households, campgrounds, and other recreational centres that are potentially exposed to the nuisance of the giant water bugs. Otherwise, incandescent light bulbs should be used when it is desired to attract the presence of these aquatic bugs either for food or scientific studies.

  3. High-Brightness Beams from a Light Source Injector The Advanced Photon Source Low-Energy Undulator Test Line Linac

    CERN Document Server

    Travish, G; Borland, M; Hahne, M; Harkay, K C; Lewellen, J W; Lumpkin, Alex H; Milton, S V; Sereno, N S

    2000-01-01

    The use of existing linacs, and in particular light source injectors, for free-electron laser (FEL) experiments is becoming more common due to the desire to test FELs at ever shorter wavelengths. The high-brightness, high-current beams required by high-gain FELs impose technical specifications that most existing linacs were not designed to meet. Moreover, the need for specialized diagnostics, especially shot-to-shot data acquisition, demands substantial modification and upgrade of conventional linacs. Improvements have been made to the Advanced Photon Source (APS) injector linac in order to produce and characterize high-brightness beams. Specifically, effort has been directed at generating beams suitable for use in the low-energy undulator test line (LEUTL) FEL in support of fourth-generation light source research. The enhancements to the linac technical and diagnostic capabilities that allowed for self-amplified spontaneous emission (SASE) operation of the FEL at 530 nm are described. Recent results, includi...

  4. High-Brightness Beams from a Light Source Injector: The Advanced Photon Source Low-Energy Undulator Test Line Linac

    OpenAIRE

    Travish, G.; Biedron, S; Borland, M.; Hahne, M.; Harkay, K.; Lewellen, J.W.; Lumpkin, A.; Milton, S.; Sereno, N.

    2000-01-01

    The use of existing linacs, and in particular light source injectors, for free-electron laser (FEL) experiments is becoming more common due to the desire to test FELs at ever shorter wavelengths. The high-brightness, high-current beams required by high-gain FELs impose technical specifications that most existing linacs were not designed to meet. Moreover, the need for specialized diagnostics, especially shot-to-shot data acquisition, demands substantial modification and upgrade of conventiona...

  5. Vitamin B12 enhances the phase-response of circadian melatonin rhythm to a single bright light exposure in humans.

    Science.gov (United States)

    Hashimoto, S; Kohsaka, M; Morita, N; Fukuda, N; Honma, S; Honma, K

    1996-12-13

    Eight young males were subjected to a single blind cross-over test to see the effects of vitamin B12 (methylcobalamin; VB12) on the phase-response of the circadian melatonin rhythm to a single bright light exposure. VB12 (0.5 mg/day) or vehicle was injected intravenously at 1230 h for 11 days, which was followed by oral administration (2 mg x 3/day) for 7 days. A serial blood sampling was performed under dim light condition (less than 200 lx) and plasma melatonin rhythm was determined before and after a single bright light exposure (2500 lx for 3 h) at 0700 h. The melatonin rhythm before the light exposure showed a smaller amplitude in the VB12 trial than in the placebo. The light exposure phase-advanced the melatonin rhythm significantly in the VB12 trail, but not in the placebo. These findings indicate that VB12 enhances the light-induced phase-shift in the human circadian rhythm. PMID:8981490

  6. Light propagation characteristics in photonic crystal fibers with α-power profiles of air hole diameter distributions and their application to fiber collimator

    Science.gov (United States)

    Yokota, Hirohisa; Higuchi, Keiichi; Imai, Yoh

    2016-08-01

    Light propagation characteristics in photonic crystal fibers (PCFs) with α-power profiles of air hole diameter distributions were theoretically investigated. It was clarified that the intensity peak of the beam propagating in the PCF with Gaussian beam excitation varied periodically with little power attenuation. It was found that the envelope of the periodic intensity variation depended on α. We theoretically demonstrated that the PCF with the α-power profile of the air hole diameter distribution could be applied to a collimator for a conventional PCF with uniform air holes in Gaussian beam excitation to reduce coupling loss, where a PCF of appropriate length with the α-power air hole diameter distribution was spliced to a conventional PCF. It was also found that the coupling efficiency was higher for a larger α.

  7. Shedding light on emotional perception: Interaction of brightness and semantic content in extrastriate visual cortex.

    Science.gov (United States)

    Schettino, Antonio; Keil, Andreas; Porcu, Emanuele; Müller, Matthias M

    2016-06-01

    The rapid extraction of affective cues from the visual environment is crucial for flexible behavior. Previous studies have reported emotion-dependent amplitude modulations of two event-related potential (ERP) components - the N1 and EPN - reflecting sensory gain control mechanisms in extrastriate visual areas. However, it is unclear whether both components are selective electrophysiological markers of attentional orienting toward emotional material or are also influenced by physical features of the visual stimuli. To address this question, electrical brain activity was recorded from seventeen male participants while viewing original and bright versions of neutral and erotic pictures. Bright neutral scenes were rated as more pleasant compared to their original counterpart, whereas erotic scenes were judged more positively when presented in their original version. Classical and mass univariate ERP analysis showed larger N1 amplitude for original relative to bright erotic pictures, with no differences for original and bright neutral scenes. Conversely, the EPN was only modulated by picture content and not by brightness, substantiating the idea that this component is a unique electrophysiological marker of attention allocation toward emotional material. Complementary topographic analysis revealed the early selective expression of a centro-parietal positivity following the presentation of original erotic scenes only, reflecting the recruitment of neural networks associated with sustained attention and facilitated memory encoding for motivationally relevant material. Overall, these results indicate that neural networks subtending the extraction of emotional information are differentially recruited depending on low-level perceptual features, which ultimately influence affective evaluations. PMID:26994832

  8. Exposure machine lfy eye type UV-LED surface light source of collimated light system%复眼式UV-LED面光源的曝光机平行光系统

    Institute of Scientific and Technical Information of China (English)

    闵秀红

    2014-01-01

    印制电路板生产设备紫外线曝光机的光源系统,其能耗大、使用维护成本高、含汞等缺陷,在倡导节能环保的当今,业界一直致力于改进。UV-LED面光源作为新一代绿色环保紫外线光源,为印制电路板曝光领域带来革命性的变化。文章通过分析传统平行光紫外曝光机光学系统特点,设计了一种平行光紫外线曝光机适用的UV-LED面光源系统,UV-LED灯珠光功率利用率大幅提高,光照均匀性优良,并且不改变曝光机结构的情况下,可直接安装使用。实验表明,采用了复眼式阵列光学透镜结构设计的UV-LED面光源系统,完全可替代传统平行光紫外曝光机光源。%The light source system of ultraviolet exposure machine which is the PCB production equipment, has high energy consumption, high using and maintenance costs, mercury and other defects. To promote energy-saving environmental protection industry today, the industry has been working to improve. UV-LED surface light source as a new generation of green ultraviolet light source, brings the revolutionary change for the PCB exposure ifeld. In this paper, through the analysis of features of the traditional collimated light ultraviolet exposure machine, it designed a kind of UV-LED surface light source system for the collimated light ultraviolet exposure machine, a substantial increase in UV-LED light pearl power efifciency, illumination uniformity is good, and does not change the exposure machine structure, can be directly installed. Experiments show that, the UV-LED surface light source system using the optical lens structure of lfy's eye array can completely replace the traditional collimated l light ultraviolet exposure machine light source.

  9. Hybrid white organic light emitting diodes with low efficiency roll-off, stable color and extreme brightness

    International Nuclear Information System (INIS)

    Highly efficient and bright hybrid white organic light emitting diodes (WOLEDs) based on simple architectures have been successfully fabricated and characterized. The optimized device can reach a maximum forward-viewing power efficiency (PE) of 20.2 lm/W, a peak forward-viewing current efficiency (CE) of 30.7 cd/A, an extremely high brightness of 95,683 cd/m2, and a Commission International de l’E clairage chromaticity coordinates of (0. 436, 0.425) at 12 V. Even at the illumination-relevant brightness of 1000 cd/m2, a forward-viewing PE of 17.0 lm/W and CE of 30.7 cd/A are obtained. Moreover, it is found that the device not only suffers slight efficiency roll-off but also exhibits a stable color during a large range of brightness, indicating that the device can satisfy the future commercial requirements. Undoubtedly, the results will be beneficial to the design of both material and device architecture for high-performance WOLEDs and next-generation solid-state lighting sources. - Highlights: • A simple HWOLED with B/O/B structure has been successfully developed. • A extremely high brigthness of 95,683 cd/m2 is obtained. • A high forward-viewing CE of 30.7 cd/A and PE of 20.2 lm/W are achieved. • Efficiency roll-off is very low and color is relatively stable

  10. Fabrication and property analysis of AIGalnP red light LED with high bright

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The LED with DBR and enhancing transmission film was grown by MOCVD. At 20 mA DC injection current, the LED peak wavelength was 623 nm, the light intensity was 200 mcd, and the output light power was 2.14 mW. The light intensity and output light power have been improved than traditional LED.

  11. Sleep, mood, and circadian responses to bright green light during sleep

    OpenAIRE

    Grandner, Michael Andrew

    2007-01-01

    Based on human and animal research, it appears that light administered in the last two hours of sleep might be particularly effective as an antidepressant and in advancing circadian rhythms. Green light might be more effective than white light. An obvious advantage of light treatment during sleep is that disturbance and time cost during waking hours might be avoided. For these reasons, we decided to explore effects of a light treatment with a green light mask used for in the last hours of sle...

  12. Circadian phase-shifting effects of a laboratory environment: a clinical trial with bright and dim light

    OpenAIRE

    Youngstedt, Shawn D.; KRIPKE, DANIEL F.; Elliott, Jeffrey A; Rex, Katharine M

    2005-01-01

    Background: Our aims were to examine the influence of different bright light schedules on mood, sleep, and circadian organization in older adults (n = 60, ages 60–79 years) with insomnia and/or depression, contrasting with responses of young, healthy controls (n = 30, ages 20–40 years).Methods: Volunteers were assessed for one week in their home environments. Urine was collected over two 24-hour periods to establish baseline acrophase of 6-sulphatoxymelatonin (aMT6s) excretion. Immediately fo...

  13. Grazing angle Mach-Zehnder interferometer using reflective phase gratings and a polychromatic, un-collimated light source.

    Science.gov (United States)

    Kemble, Camille K; Auxier, Julie; Lynch, Susanna K; Bennett, Eric E; Morgan, Nicole Y; Wen, Han

    2010-12-20

    Normal incidence Talbot-Lau interferometers in x-ray applications have the drawbacks of low fringe visibility with polychromatic sources when the wave propagation distance is increased to achieve higher phase sensitivity, and when fabrication limits the attainable grating density. In contrast, reflective gratings illuminated at grazing angles have dramatically higher effective densities than their physical values. However, new designs are needed for far field interferometers using grazing angle geometry with incoherent light sources. We show that, with the appropriate design and choice of reflective phase gratings, there exist pairs of interfering pathways of exactly equal lengths independent of the incoming beam's incidence angle and wavelength. With a visible light grazing angle Mach-Zehnder interferometer, we show the conditions for achieving near ideal fringe visibility and demonstrate both absolute and differential phase-contrast imaging. We also describe the design parameters of an x-ray interferometer and key factors for its implementation.

  14. LCD brightness decay due to particulate contamination of back light unit

    Science.gov (United States)

    Kim, Sanghoon; Lee, Sang-Chul; Yook, Se-Jin; Choi, Jung-Uk; Ahn, Kang-Ho

    2013-01-01

    So far, particulate contamination problems occurring in cleanroom environments have been intensively investigated by considering the product yield in semiconductor manufacturing or liquid crystal display (LCD) manufacturing. This study, however, focused on the particulate contamination problem causing the degradation of LCD TVs run in common environments. A field test was conducted by running a LCD TV in an office room for 60 days in order to collect and analyze the particles contaminating the backlight unit (BLU) of the LCD TV. Based on the field test result, soot particles were generated to simulate the contaminant particles, and an accelerated test was performed by exposing the LCD TV to a soot aerosol of relatively high concentration. As the exposure time was increased, the degree of particulate contamination of the BLU became more severe, and the decay rate of the LCD brightness increased. As a result, the particulate contamination of the BLU was found to greatly affect the decay rate of the LCD brightness. A numerical simulation was performed to elucidate the mechanism of particle influx into the BLU and to predict the particle deposition pattern. The contaminant particles could enter into the BLU through the gaps on the BLU casing due to the air flow induced by natural convection in the BLU. The particles were thought to have been deposited on the walls in the BLU, especially at the corner regions.

  15. The Role of Bright Light during Night Work on Stress and Health Status of Shift Work Nurses

    Directory of Open Access Journals (Sweden)

    Mostafa Hosseini

    2009-04-01

    Full Text Available Research has shown that shift work, in particular night work, can have negative effects on the health, safety and well-being of workers. Our study assessed, in a hospital setting, the effects of bright light (BL on general health and psychological problems during night shift work. In an experimental design, 15 female nurses at a general hospital that located in Tehran were exposed to moderate bright light (2000 lx during night work. The evaluation of general health status, job stress, and burnout syndrome conditions was done as follows: The 28-item General Health Questionnaire (GHQ-28 was used as a screening tool for the detection of general health status; for assessing the level of stress, perception stress scale (PSS was filled; and for burnout syndrome conditions, burnout self-report questionnaire (BSR was completed. T-test and paired t-test analysis were used to assess the association between BL exposure for a total of 30 min during each night shift and changes in general health status, job stress and burnout syndrome. This study clearly shows that BL administration could not reduce anxiety symptoms, somatic symptoms, severe depression and improved social dysfunction significantly during night shift. However, BL exposure significantly decreased the perception stress (P=0.008 and burnout syndrome (P=0.06 during night permanent shift. These results suggest that BL might have provoked changes in perception stress and burnout syndrome of nurses working night permanent shift.

  16. A correlation between intrinsic brightness and average decay rate of Swift UVOT GRB optical/UV light curves

    CERN Document Server

    Oates, S R; De Pasquale, M; Schady, P; Breeveld, A A; Holland, S T; Kuin, N P M; Marshall, F E

    2012-01-01

    We examine a sample of 48 Swift/UVOT long Gamma-ray Burst light curves and find a correlation between the logarithmic luminosity at 200s and average decay rate determined from 200s onwards, with a Spearman rank coefficient of -0.58 at a significance of 99.998% (4.2 sigma). We discuss the causes of the log L_200s - alpha_>200s correlation, finding it to be an intrinsic property of long GRBs, and not resulting from the selection criteria. We find two ways to produce the correlation. One possibility is that there is some property of the central engine, outflow or external medium that affects the rate of energy release so that the bright afterglows release their energy more quickly and decay faster than the fainter afterglows. Alternatively, the correlation may be produced by variation of the observers viewing angle, with observers at large viewing angles observing fainter and slower decaying light curves.

  17. High-brightness semipolar (2021¯) blue InGaN/GaN superluminescent diodes for droop-free solid-state lighting and visible-light communications.

    Science.gov (United States)

    Shen, Chao; Ng, Tien Khee; Leonard, John T; Pourhashemi, Arash; Nakamura, Shuji; DenBaars, Steven P; Speck, James S; Alyamani, Ahmed Y; El-Desouki, Munir M; Ooi, Boon S

    2016-06-01

    A high-brightness, droop-free, and speckle-free InGaN/GaN quantum well blue superluminescent diode (SLD) was demonstrated on a semipolar (2021¯) GaN substrate. The 447-nm emitting SLD has a broad spectral linewidth of 6.3 nm at an optical power of 123 mW. A peak optical power of 256 mW was achieved at 700 mA CW injection current. By combining YAG:Ce phosphor, SLD-generated white light shows a color-rendering index (CRI) of 68.9 and a correlated color temperature (CCT) of 4340 K. The measured frequency response of the SLD revealed a -3  dB bandwidth of 560 MHz, thus demonstrating the feasibility of the device for both solid-state lighting (SSL) and visible-light communication (VLC) applications. PMID:27244426

  18. High-brightness semipolar (2021¯) blue InGaN/GaN superluminescent diodes for droop-free solid-state lighting and visible-light communications

    KAUST Repository

    Shen, Chao

    2016-05-25

    A high-brightness, droop-free, and speckle-free InGaN/GaN quantum well blue superluminescent diode (SLD) was demonstrated on a semipolar (2021) GaN substrate. The 447-nm emitting SLD has a broad spectral linewidth of 6.3 nm at an optical power of 123 mW. A peak optical power of 256 mW was achieved at 700 mA CW injection current. By combining YAG:Ce phosphor, SLD-generated white light shows a color-rendering index (CRI) of 68.9 and a correlated color temperature (CCT) of 4340 K. The measured frequency response of the SLD revealed a -3 dB bandwidth of 560 MHz, thus demonstrating the feasibility of the device for both solid-state lighting (SSL) and visible-light communication (VLC) applications. © 2016 Optical Society of America.

  19. Broadband and high-brightness light source: glass-clad Ti:sapphire crystal fiber.

    Science.gov (United States)

    Wang, Shih-Chang; Yang, Teng-I; Jheng, Dong-Yo; Hsu, Chun-Yang; Yang, Tzu-Te; Ho, Tuan-Shu; Huang, Sheng-Lung

    2015-12-01

    High-brightness near-infrared broadband amplified spontaneous emission (ASE) was generated by glass-clad Ti:sapphire crystal fibers, which were developed using the co-drawing laser-heated pedestal growth method. As much as 29.2 mW of ASE power was generated using 520 nm laser diodes as the excitation source on an a-cut, 18 μm core-diameter Ti:sapphire crystal fiber (CF). The 3 dB bandwidth was 163.8 nm, and the radiance was 53.94  W·mm(-2) sr(-1). The propagation loss of the glass-clad sapphire CF measured using the cutback method was 0.017  cm(-1) at 780 nm. For single-mode applications, more than 100 μW of power was coupled into a SM600 single-mode fiber. PMID:26625059

  20. Investigation of Pattern-Induced Brightness Non-uniformity in Active-Matrix Organic Light-Emitting Diode Displays

    Science.gov (United States)

    Kim, Kyoung-Bo; Park, Hye-Hyang; Kwon, Ohseob; Kim, Moojin; Lee, Ki-Yong; Park, Yongwoo; Choi, JongHyun; Yu, CheolHo; Kim, Hye-Dong; Kim, Sung Chul; Chung, Ho-Kyoon

    2008-01-01

    We recently improved the brightness non-uniformity in active-matrix organic light-emitting diode (AMOLED) regarding non-uniform laser energy distribution by applying a “shot mixing” technique in sequential lateral solidification (SLS) method. Although the new SLS technique was employed, another brightness non-uniformity that appeared as oblique lines on AMOLED panels became a crucial issue. In this work, we attempted to investigate the origins of the non-uniformity. Our systematic analysis on the oblique lines revealed that the line type non-uniformity was attributed to both the SLS process and the thin-film transistor (TFT) fabrication processes. In particular, we found that such oblique patterns might be related to moiré patterns that appear when primary grain boundaries aligned in a repetitive pattern is placed over other repetitive TFT patterns such as metal lines. We adopted a method to diminish the moiré pattern type non-uniformity by applying top emission TFT structure.

  1. Color mixing collimating lamp based on RGB LEDs

    Science.gov (United States)

    Lo, Yi-Chien; Moreno, Ivan; Chiu, Bo-Chun; Chien, Wei-Ting; Cai, Jhih-You; Chang, Yu-Yu; Sun, Ching-Cherng

    2012-10-01

    A novel light luminaire is proposed and experimentally analyzed, which efficiently mixes and projects the tunable light from red, green and blue (RGB) light-emitting diodes (LEDs). Simultaneous light collimation and color mixing is a challenging task because most collimators separate colors, and most color mixers spread the light beam. We performed an experimental study to find a balance between optical efficiency and color uniformity by changing light recycling and color mixing.

  2. Improvement of Efficiency and Brightness of Red Organic Light-Emitting Devices Using Double-Quantum-Well Configuration

    Science.gov (United States)

    Mi, Rui; Cheng, Gang; Zhao, Yi; Xie, Wen-Fa; Hou, Jing-Ying; Ding, Tao; Liu, Shi-Yong

    2004-03-01

    We present red double-quantum-well organic light-emitting devices (DQW-OLEDs), in which N,N-bis-(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyo-4,4'-diamine (NPB) is used as potential barriers and hole transport layer, 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-thtramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped tris (8-hydroxyquinoline) aluminium (Alq3) as potential wells and emitter, undoped Alq3 as electron transport layer, respectively. The turn-on voltage is about 4 V. The maximum brightness and electroluminescent (EL) efficiency of the DQW device can reach 5916 cd m-2 at 16 V and 2.85 cd A-1 at 7 V, respectively. In addition, the EL efficiency of the DQW device is relatively independent of the drive voltage in the range from 5 V to 16 V.

  3. Improvement of Efficiency and Brightness of Red Organic Light-Emitting Devices Using Double-Quantum-Well Configuration

    Institute of Scientific and Technical Information of China (English)

    MI Rui; CHENG Gang; ZHAO Yi; XIE Wen-Fa; HOU Jing-Ying; DING Tao; LIU Shi-Yong

    2004-01-01

    @@ We present red double-quantum-well organic light-emitting devices (DQW-OLEDs), in which N,N-bis-(1-naphthyl)N,N′-diphenyl-1,1′-biphenyo-4,4'-diamine (NPB) is used as potential barriers and hole transport layer, 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7, 7-thtramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) doped tris (8-hydroxyquinoline) aluminum (Alq3) as potential wells and emitter, undoped Alq3 as electron transport layer, respectively. The turn-on voltage is about 4 V. The maximum brightness and electroluminescent (EL) efficiency of the DQW device can reach 5916cd m-2 at 16 V and 2.85cd A-1 at 7 V, respectively. In addition, the EL efficiency of the DQW device is relatively independent of the drive voltage in the range from 5 V to 16 V.

  4. Bright infrared quantum-dot light-emitting diodes through inter-dot spacing control

    KAUST Repository

    Sun, Liangfeng

    2012-05-06

    Infrared light-emitting diodes are currently fabricated from direct-gap semiconductors using epitaxy, which makes them expensive and difficult to integrate with other materials. Light-emitting diodes based on colloidal semiconductor quantum dots, on the other hand, can be solution-processed at low cost, and can be directly integrated with silicon. However, so far, exciton dissociation and recombination have not been well controlled in these devices, and this has limited their performance. Here, by tuning the distance between adjacent PbS quantum dots, we fabricate thin-film quantum-dot light-emitting diodes that operate at infrared wavelengths with radiances (6.4 W sr \\'1 m \\'2) eight times higher and external quantum efficiencies (2.0%) two times higher than the highest values previously reported. The distance between adjacent dots is tuned over a range of 1.3 nm by varying the lengths of the linker molecules from three to eight CH 2 groups, which allows us to achieve the optimum balance between charge injection and radiative exciton recombination. The electroluminescent powers of the best devices are comparable to those produced by commercial InGaAsP light-emitting diodes. By varying the size of the quantum dots, we can tune the emission wavelengths between 800 and 1,850 nm.© 2012 Macmillan Publishers Limited.

  5. 光路中使用准直透镜时应注意的一个问题%A should the notice question of using collimated lens in light path

    Institute of Scientific and Technical Information of China (English)

    施德恒; 陈玉科; 耿明磊

    2000-01-01

    In collimated light path,when rays of light pass through collimated lens else than a plane waves,at the same time a spherical waves is brought for reflect of the lens surface.The distance from convergent point of spherical waves to the lens is equal to f(n-1)/2n.This paper presents theory and experiment validate,and discuss should the notice question of using collimated lens in holographic light path.%在准直光路中,经过准直透镜后,除得到一束平面波外,由于透镜前后表面的反射,还附加产生一个会聚在f(n-1)/2n处的球面波。本文给出了理论推导和实验验证,并讨论了在全息光路中使用准直透镜时应该注意的问题。

  6. Nature of light rain during presence and absence of bright band

    Indian Academy of Sciences (India)

    Mahen Konwar; R S Maheskumar; S K Das; S B Morwal

    2012-08-01

    This paper reports the evolution of rain drop size distribution (DSD) during bright band (BB) and no-BB (NBB) conditions of low intensity rainfall events as observed by a vertically pointing Micro Rain Radar (MRR) over Pune (18.58°N, 73.92°E), India. The BB is identified by enhanced radar reflectivity factor (dBZ) at the 0°C isotherm. The gradient of hydrometeor fall velocity is found to be a good indicator in identifying the melting layer when enhanced radar reflectivity at melting layer is not prominent. The storm structures as observed by the MRR are compared with CloudSat observations that provide evidence of ice hydrometeor at ∼−60°C with clear indication of BB at 0°C. Storm heights at warmer than 0°C are evident during NBB conditions from CloudSat. This suggests that warm rain processes are responsible for producing rain during NBB conditions. During BB conditions, bimodal DSDs below the melting layer are observed at lower altitudes. The DSDs of shallow warm precipitating systems of NBB conditions are monomodal at all the altitudes. Significantly, normalized DSDs are found to be bimodal for BB conditions, and monomodal for NBB conditions which confirm different dominant microphysical processes. It is found that the observed bimodal DSDs during BB conditions are mainly due to the collision, coalescence and break-up processes. During NBB conditions, number and size of large raindrops grow while reaching the ground without much breakup. The radar reflectivity and rainfall intensity (mmh−1) relationship of the form = b are found out for BB and NBB conditions. Existing different microphysical processes lead to large coefficient in the – relationship with small exponent during BB conditions while during NBB conditions the coefficients are small with large exponents.

  7. Three-Week Bright-Light Intervention Has Dose-Related Effects on Threat-Related Corticolimbic Reactivity and Functional Coupling

    DEFF Research Database (Denmark)

    Fisher, Patrick M; Madsen, Martin K; Mc Mahon, Brenda;

    2014-01-01

    -11.0 kilolux) for 30 minutes daily over a period of 3 weeks. Additionally, we considered serotonin transporter-linked polymorphic region (5-HTTLPR) genotype status as a model for differences in serotonin signaling and moderator of intervention effects. RESULTS: Bright-light dose significantly negatively......BACKGROUND: Bright-light intervention is reported to successfully treat depression, in particular seasonal affective disorder, but the neural pathways and molecular mechanisms mediating its effects are unclear. An amygdala-prefrontal cortex corticolimbic circuit regulates responses to salient...... environmental stimuli (e.g., threat) and may underlie these effects. Serotonin signaling modulates this circuit and is implicated in the pathophysiology of seasonal and other affective disorders. METHODS: We evaluated the effects of a bright-light intervention protocol on threat-related corticolimbic reactivity...

  8. Acute effects of bright light and caffeine on nighttime melatonin and temperature levels in women taking and not taking oral contraceptives

    Science.gov (United States)

    Wright, K. P. Jr; Myers, B. L.; Plenzler, S. C.; Drake, C. L.; Badia, P.; Czeisler, C. A. (Principal Investigator)

    2000-01-01

    Caffeine and bright light effects on nighttime melatonin and temperature levels in women were tested during the luteal phase of the menstrual cycle (n=30) or the pseudo luteal phase for oral contraceptive users (n=32). Participants were randomly assigned to receive either bright (5000 lux) or dim room light (oral contraceptive users. The results for women in the luteal phase of the menstrual cycle are consistent with our previous findings in men. The results also suggest that oral contraceptives may alter the effects of caffeine on nighttime melatonin levels.

  9. Transcranial bright light treatment via the ear canals in seasonal affective disorder: a randomized, double-blind dose-response study

    OpenAIRE

    Jurvelin, Heidi; Takala, Timo; Nissilä, Juuso; Timonen, Markku; Rüger, Melanie; Jokelainen, Jari; Räsänen, Pirkko

    2014-01-01

    Background Bright light treatment is effective for seasonal affective disorder (SAD), although the mechanisms of action are still unknown. We investigated whether transcranial bright light via the ear canals has an antidepressant effect in the treatment of SAD. Methods During the four-week study period, 89 patients (67 females; 22 males, aged 22-65, mean ± SD age: 43.2 ± 10.9 years) suffering from SAD were randomized to receive a 12-min daily dose of photic energy of one of three intensities ...

  10. The envelope of IRC+10216 reflecting the galactic light: UBV surface brightness photometry and interpretation

    CERN Document Server

    Mauron, N; López, B

    2003-01-01

    We present and analyse new optical images of the dust envelope surrounding the high mass-loss carbon star IRC+10216. This envelope is seen due to external illumination by galactic light. Intensity profiles and colors of the nebula were obtained in the UBV bandpasses. The data are compared with the results of a radiative transfer model calculating multiple scattering of interstellar field photons by dust grains with a single radius. The data show that the observed radial shape of the nebula, especially its half maximum radius, does not depend on wavelength (within experimental errors), suggesting that grains scatter in the grey regime, etc, etc (this abstract has been shortened)

  11. Research on Brightness Measurement of Intense Electron Beam

    CERN Document Server

    Wang, Yuan; Zhang, Huang; Yang, GuoJun; Li, YiDing; Li, Jin

    2015-01-01

    The mostly research fasten on high emission density of injector to study electron beam's brightness in LIA. Using the injector(2MeV) was built to research brightness of multi-pulsed high current(KA) electron beam, and researchs three measurement method (the pepper-pot method, beam collimator without magnetic field, beam collimator with magnetic field method) to detect beam's brightness with time-resolved measurement system.

  12. High-brightness organic light-emitting diodes for optogenetic control of Drosophila locomotor behaviour

    Science.gov (United States)

    Morton, Andrew; Murawski, Caroline; Pulver, Stefan R.; Gather, Malte C.

    2016-08-01

    Organic light emitting diodes (OLEDs) are in widespread use in today’s mobile phones and are likely to drive the next generation of large area displays and solid-state lighting. Here we show steps towards their utility as a platform technology for biophotonics, by demonstrating devices capable of optically controlling behaviour in live animals. Using devices with a pin OLED architecture, sufficient illumination intensity (0.3 mW.mm‑2) to activate channelrhodopsins (ChRs) in vivo was reliably achieved at low operating voltages (5 V). In Drosophila melanogaster third instar larvae expressing ChR2(H134R) in motor neurons, we found that pulsed illumination from blue and green OLEDs triggered robust and reversible contractions in animals. This response was temporally coupled to the timing of OLED illumination. With blue OLED illumination, the initial rate and overall size of the behavioural response was strongest. Green OLEDs achieved roughly 70% of the response observed with blue OLEDs. Orange OLEDs did not produce contractions in larvae, in agreement with the spectral response of ChR2(H134R). The device configuration presented here could be modified to accommodate other small model organisms, cell cultures or tissue slices and the ability of OLEDs to provide patterned illumination and spectral tuning can further broaden their utility in optogenetics experiments.

  13. High-brightness organic light-emitting diodes for optogenetic control of Drosophila locomotor behaviour.

    Science.gov (United States)

    Morton, Andrew; Murawski, Caroline; Pulver, Stefan R; Gather, Malte C

    2016-01-01

    Organic light emitting diodes (OLEDs) are in widespread use in today's mobile phones and are likely to drive the next generation of large area displays and solid-state lighting. Here we show steps towards their utility as a platform technology for biophotonics, by demonstrating devices capable of optically controlling behaviour in live animals. Using devices with a pin OLED architecture, sufficient illumination intensity (0.3 mW.mm(-2)) to activate channelrhodopsins (ChRs) in vivo was reliably achieved at low operating voltages (5 V). In Drosophila melanogaster third instar larvae expressing ChR2(H134R) in motor neurons, we found that pulsed illumination from blue and green OLEDs triggered robust and reversible contractions in animals. This response was temporally coupled to the timing of OLED illumination. With blue OLED illumination, the initial rate and overall size of the behavioural response was strongest. Green OLEDs achieved roughly 70% of the response observed with blue OLEDs. Orange OLEDs did not produce contractions in larvae, in agreement with the spectral response of ChR2(H134R). The device configuration presented here could be modified to accommodate other small model organisms, cell cultures or tissue slices and the ability of OLEDs to provide patterned illumination and spectral tuning can further broaden their utility in optogenetics experiments. PMID:27484401

  14. High-brightness organic light-emitting diodes for optogenetic control of Drosophila locomotor behaviour

    Science.gov (United States)

    Morton, Andrew; Murawski, Caroline; Pulver, Stefan R.; Gather, Malte C.

    2016-08-01

    Organic light emitting diodes (OLEDs) are in widespread use in today’s mobile phones and are likely to drive the next generation of large area displays and solid-state lighting. Here we show steps towards their utility as a platform technology for biophotonics, by demonstrating devices capable of optically controlling behaviour in live animals. Using devices with a pin OLED architecture, sufficient illumination intensity (0.3 mW.mm-2) to activate channelrhodopsins (ChRs) in vivo was reliably achieved at low operating voltages (5 V). In Drosophila melanogaster third instar larvae expressing ChR2(H134R) in motor neurons, we found that pulsed illumination from blue and green OLEDs triggered robust and reversible contractions in animals. This response was temporally coupled to the timing of OLED illumination. With blue OLED illumination, the initial rate and overall size of the behavioural response was strongest. Green OLEDs achieved roughly 70% of the response observed with blue OLEDs. Orange OLEDs did not produce contractions in larvae, in agreement with the spectral response of ChR2(H134R). The device configuration presented here could be modified to accommodate other small model organisms, cell cultures or tissue slices and the ability of OLEDs to provide patterned illumination and spectral tuning can further broaden their utility in optogenetics experiments.

  15. Characterization of Embedded BPM Collimators

    CERN Document Server

    VALENTINO, Gianluca

    2015-01-01

    During LS1, 16 tertiary collimators (TCTs) and 2 secondary collimators (TCSGs) in IR6 were replaced by new embedded BPM collimators. The BPM functionality allows the possibility to align the collimators more quickly and therefore be able to respond faster to machine configuration changes, as well as a direct monitoring of the beam orbit at the collimators. Following an initial commissioning phase, an MD was carried out to test the new collimators and acquisition electronics with beam in the LHC.

  16. Heralded source of bright multi-mode mesoscopic sub-Poissonian light.

    Science.gov (United States)

    Iskhakov, T Sh; Usenko, V C; Andersen, U L; Filip, R; Chekhova, M V; Leuchs, G

    2016-05-15

    In a direct detection scheme, we observed 7.8 dB of twin-beam squeezing for multi-mode two-color squeezed vacuum generated via parametric downconversion. Applying post-selection, we conditionally prepared a sub-Poissonian state of light containing 6.3·105 photons per pulse on the average with the Fano factor 0.63±0.01. The scheme can be considered as the heralded preparation of pulses with the mean energy varying between tens and hundreds of fJ and the uncertainty considerably below the shot-noise level. Such pulses can be used in metrology (for instance, for radiometer calibration), as well as for probing multi-mode nonlinear optical effects. PMID:27176949

  17. Efficient and bright colloidal quantum dot light-emitting diodes via controlling the shell thickness of quantum dots.

    Science.gov (United States)

    Shen, Huaibin; Lin, Qinli; Wang, Hongzhe; Qian, Lei; Yang, Yixing; Titov, Alexandre; Hyvonen, Jake; Zheng, Ying; Li, Lin Song

    2013-11-27

    In this paper, we use a simple device architecture based on solution-processed ZnO nanoparticles (NPs) as the electron injection/transport layer and bilayer structure of poly(ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) as the hole injection/transport layer to assess the effect of shell thickness on the properties of quantum-dot-based light emitting diodes (QD-LEDs), comprising CdSe/CdS/ZnS core-shell QDs as the emitting layer. QDs with varying shell thickness were assessed to determine the best option of shell thickness, and the best improvement in device performance was observed when the shell thickness was 2.1 nm. Thereafter, different emissions of QDs, but with optimized same shell thickness (∼2.1 nm), were selected as emitters to be fabricated into same structured QD-LEDs. Highly bright orange-red and green QD-LEDs with peak luminances up to ∼30 000 and ∼52 000 cd m(-2), and power efficiencies of 16 and 19.7 lm W(-1), respectively, were demonstrated successfully. These results may demonstrate a striking basic prototype for the commercialization of QD-based displays and solid-state lightings. PMID:24191742

  18. High brightness three-dimensional light field display based on the aspheric substrate Fresnel-lens-array with eccentric pupils

    Science.gov (United States)

    Gao, Xin; Sang, Xinzhu; Yu, Xunbo; Cao, Xuemei; Chen, Zhidong; Yan, Binbin; Yuan, Jinhui; Wang, Kuiru; Yu, Chongxiu; Dou, Wenhua; Xiao, Liquan

    2016-02-01

    The brightness and viewing field of the reproductive three-dimensional (3D) image are crucial factors to realize a comfortable 3D perception for the light field display based on the liquid crystal device (LCD). To improve the illuminance of 3D image with sub-image-units with small aperture angles and enlarge the viewing field, the illuminance of the Fresnel-lens combining with the sub-images on LCD is analyzed and designed. Theoretical and experimental results show that the Fresnel-lens-array with eccentric pupil(FAEP) can address above problems. A 3D light field display based on LCD with FAEP and directional diffuser screen are used to reconstruct the target 3D field. 25 parallax sub-images are projected to the directional diffuser screen to verify the improvement of illuminance and viewing field. To reduce eccentric aberration introduced by eccentric pupil, a novel structure of Fresnel-lens-array is presented to reduce the aberration. The illuminance and viewing field are well promoted at the same time. 3D image with the high quality can be achieved.

  19. Wake fields in SLAC Linac Collimators

    Energy Technology Data Exchange (ETDEWEB)

    Novokhatski, Alexander [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Decker, F. -J. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Smith, H. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Sullivan, M. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)

    2014-12-02

    When a beam travels near collimator jaws, it gets an energy loss and a transverse kick due to the backreaction of the beam field diffracted from the jaws. The effect becomes very important for an intense short bunch when a tight collimation of the background beam halo is required. In the Linac Coherent Light Source at SLAC a collimation system is used to protect the undulators from radiation due to particles in the beam halo. The halo is most likely formed from gun dark current or dark current in some of the accelerating sections. However, collimators are also responsible for the generation of wake fields. The wake field effect from the collimators not only brings an additional energy jitter and change in the trajectory of the beam, but it also rotates the beam on the phase plane, which consequently leads to a degradation of the performance of the Free Electron Laser at the Linac Coherent Light Source. In this paper, we describe a model of the wake field radiation in the SLAC linac collimators. We use the results of a numerical simulation to illustrate the model. Based on the model, we derive simple formulas for the bunch energy loss and the average kick. In addition, we also present results from experimental measurements that confirm our model.

  20. A new astronomical method for determining the brightness of the night sky and its application to study long-term changes in the level of light pollution

    Science.gov (United States)

    Ściężor, T.

    2013-10-01

    In this paper, I present a new method that has been developed for determining the brightness of a cloudless night sky, on the basis of widely available amateur observations of comets. The tests show the correctness of the method, which makes it possible to determine the level of light pollution, defined as the brightness of the artificial sky glow, through the use of the archival observations of comets. The use of data bases of comet observations in Poland in the period 1994-2009 has led to a positive verification of the known model map of the brightness of the night sky. Also, it has been possible to find changes in the level of light pollution in this period, at the selected observation sites.

  1. Research data supporting "Bright and efficient blue polymer light emitting diodes with reduced operating voltages processed entirely at low-temperature"

    OpenAIRE

    Hoye, R. L. Z.; Musselman, K.P.; Chua, M. R.; Sadhanala, A.; Raninga, R. D.; MacManus-Driscoll, J. L.; Friend, R. H.; Credgington, D.

    2015-01-01

    Raw data for all figures and ESI from manuscript "Bright and efficient blue polymer light emitting diodes with reduced operating voltages processed entirely at low-temperature" published in Journal of Materials Chemistry C (http://dx.doi.org/10.1039/C5TC01581B).

  2. Bright light therapy as part of a multicomponent management program improves sleep and functional outcomes in delirious older hospitalized adults

    Directory of Open Access Journals (Sweden)

    Chong MS

    2013-05-01

    Full Text Available Mei Sian Chong,1 Keng Teng Tan,2 Laura Tay,1 Yoke Moi Wong,1 Sonia Ancoli-Israel3,41Department of Geriatric Medicine, Tan Tock Seng Hospital, Singapore; 2Department of Pharmacy, Tan Tock Seng Hospital, Singapore; 3Departments of Psychiatry and Medicine, University of California, San Diego, CA, USA; 4VA Center of Excellence for Stress and Mental Health (CESAMH, San Diego, CA, USAObjective: Delirium is associated with poor outcomes following acute hospitalization. A specialized delirium management unit, the Geriatric Monitoring Unit (GMU, was established. Evening bright light therapy (2000–3000 lux; 6–10 pm daily was added as adjunctive treatment, to consolidate circadian activity rhythms and improve sleep. This study examined whether the GMU program improved sleep, cognitive, and functional outcomes in delirious patients.Method: A total of 228 patients (mean age = 84.2 years were studied. The clinical characteristics, delirium duration, delirium subtype, Delirium Rating Score (DRS, cognitive status (Chinese Mini–Mental State Examination, functional status (modified Barthel Index [MBI], and chemical restraint use during the initial and predischarge phase of the patient’s GMU admission were obtained. Nurses completed hourly 24-hour patient sleep logs, and from these, the mean total sleep time, number of awakenings, and sleep bouts (SB were computed.Results: The mean delirium duration was 6.7 ± 4.6 days. Analysis of the delirium subtypes showed that 18.4% had hypoactive delirium, 30.2% mixed delirium, and 51.3% had hyperactive delirium. There were significant improvements in MBI scores, especially for the hyperactive and mixed delirium subtypes (P < 0.05. Significant improvements were noted on the DRS sleep–wake disturbance subscore, for all delirium-subtypes. The mean total sleep time (7.7 from 6.4 hours (P < 0.05 and length of first SB (6.0 compared with 5.3 hours (P < 0.05 improved, with decreased mean number of SBs and awakenings. The

  3. BRIGHT RAY-LIKE FEATURES IN THE AFTERMATH OF CORONAL MASS EJECTIONS: WHITE LIGHT VERSUS ULTRAVIOLET SPECTRA

    Energy Technology Data Exchange (ETDEWEB)

    Ciaravella, A. [INAF-Osservatorio Astronomico di Palermo, P.za Parlamento 1, I-90134 Palermo (Italy); Webb, D. F. [Institute for Scientific Research, Boston College, Newton, MA 02459 (United States); Giordano, S. [INAF-Osservatorio Astrofisico di Torino, via Osservatorio 20, I-10025 Pino Torinese (Italy); Raymond, J. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2013-03-20

    Current sheets (CSs) are important signatures of magnetic reconnection in the eruption of confined solar magnetic structures. Models of coronal mass ejections (CMEs) involve formation of a CS connecting the ejected flux rope with the post-eruption magnetic loops. CSs have been identified in white light (WL) images of CMEs as narrow rays trailing the outward moving CME core, and in ultraviolet spectra as narrow bright features emitting the [Fe XVIII] line. In this work, samples of rays detected in WL images or in ultraviolet spectra have been analyzed. Temperatures, widths, and line intensities of the rays have been measured, and their correlation to the CME properties has been studied. The samples show a wide range of temperatures with hot, coronal, and cool rays. In some cases, the UV spectra support the identification of rays as CSs, but they show that some WL rays are cool material from the CME core. In many cases, both hot and cool material are present, but offset from each other along the Ultraviolet Coronagraph Spectrometer slit. We find that about 18% of the WL rays show very hot gas consistent with the CS interpretation, while about 23% show cold gas that we attribute to cool prominence material draining back from the CME core. The remaining events have ordinary coronal temperatures, perhaps because they have relaxed back to a quiescent state.

  4. Very Bright and Efficient Microcavity Top-Emitting Quantum Dot Light-Emitting Diodes with Ag Electrodes.

    Science.gov (United States)

    Liu, Guohong; Zhou, Xiang; Chen, Shuming

    2016-07-01

    The microcavity effect in top-emitting quantum dot light-emitting diodes (TQLEDs) is theoretically and experimentally investigated. By carefully optimizing the cavity length, the thickness of the top Ag electrode and the thickness of the capping layer, very bright and efficient TQLEDs with external quantum efficiency (EQE) of 12.5% are demonstrated. Strong dependence of luminance and efficiency on cavity length is observed, in good agreement with theoretical calculation. By setting the normal-direction resonant wavelength around the peak wavelength of the intrinsic emission, highest luminance of 112 000 cd/m(2) (at a driving voltage of 7 V) and maximum current efficiency of 27.8 cd/A are achieved, representing a 12-fold and a 2.1-fold enhancement compared to 9000 cd/m(2) and 13.2 cd/A of the conventional bottom emitting devices, respectively, whereas the highest EQE of 12.5% is obtained by setting the resonant wavelength 30 nm longer than the peak wavelength of the intrinsic emission. Benefit from the very narrow spectrum of QDs and the low absorption of silver electrodes, the potential of microcavity effect can be fully exploited in TQLEDs.

  5. Micro-structure Engineering of InGaN/GaN Quantum Wells for High Brightness Light Emitting Devices

    KAUST Repository

    Shen, Chao

    2013-05-01

    L > 3 μm in the array configuration would allow the building of practical devices. Overall, this work demonstrated a novel top-down approach to manufacture large effective-area, high brightness emitters for solid-state lighting applications.

  6. GLOBE at Night: a Worldwide Citizen-Science Program to Increase Awareness of Light Pollution by Measuring Night Sky Brightness

    Science.gov (United States)

    Walker, C. E.; Pompea, S. M.

    2011-12-01

    The emphasis in the international citizen-science, star-hunting campaign, GLOBE at Night, is in bringing awareness to the public on issues of light pollution. Light pollution threatens not only observatory sites and our "right to starlight", but can affect energy consumption, wildlife and health. GLOBE at Night has successfully reached a few 100,000 citizen-scientists. What has contributed to its success? Foundational resources are available to facilitate the public's participation in promoting dark skies awareness. The GLOBE at Night website explains clearly the simple-to-participate-in 5 step program and offers background information and interactive games on key concepts. To promote the campaign via popular social media, GLOBE at Night created Facebook and Twitter pages. The program has been expanded to include trainings of the general public, but especially educators in schools, museums and science centers, in unique ways. Education kits for dark skies awareness have been distributed at the training workshops. The kit includes material for a light shielding demonstration, a digital Sky Quality Meter and "Dark Skies Rangers" activities. The activities are on how unshielded light wastes energy, how light pollution affects wildlife and how one can participate in a citizen-science star-hunt like GLOBE at Night. To increase participation in the 2011 campaign, children and adults submitted their sky brightness measurements in real time with smart phones or tablets using the web application at www.globeatnight.org/webapp/. With smart phones and tablets, the location, date and time register automatically. For those without smart mobile devices, user-friendly tools on the GLOBE at Night report page were reconfigured to determine latitude and longitude more easily and accurately. As a proto-type for taking multiple measurements, people in Tucson found it easy to adopt a street and take measurements every mile for the length of the street. The grid of measurements

  7. Mississippi Power ampersand Light Company: A departure point for extension of the bright line: between federal and state regulatory jurisdiction over public utilities

    International Nuclear Information System (INIS)

    This article suggests that the Supreme Court's decision in Mississippi Power ampersand Light Co. v. Mississippi ex rel. Moore (MP ampersand L) issued on June 29, 1988 may provide an appropriated departure point from which to extend the bright line between FERC and state PUC jurisdiction to deal with the costs associated with failed nuclear power plants. The issue of a jurisdictional bright line extension initially is posed where state PUCs, in setting retail electric rates, disallow or severely restrict recovery costs of failed unclear power plan costs from retail ratepayers. The article first provides a factual background against which to examine the jurisdictional bright line law. Second, it analyzes the MP ampersand L decision's clear affirmation of the statutory, judicial, and constitutional bases for drawing the jurisdictional bright line that are found in Part II of the Federal Power Act, the file rate doctrine, preemption principles, and the commerce clause of the Constitution. Finally, it discusses the extension of that jurisdictional bright line to deal with the current and future costs of inoperable, abandoned, or canceled nuclear power plants

  8. Improvement in Fatigue, Sleepiness, and Health-Related Quality of Life with Bright Light Treatment in Persons with Seasonal Affective Disorder and Subsyndromal SAD

    Directory of Open Access Journals (Sweden)

    Cecilia Rastad

    2011-01-01

    Full Text Available Objective. To investigate the effects of bright light treatment for secondary outcome measures and to explore and validate empirically derived subgroups and treatment effects in subgroups. Methods. A descriptive design. A sample of forty-nine persons (mean age of 45.8 with clinically assessed seasonal affective disorder (SAD or subsyndromal SAD (S-SAD participated in a two-group clinical trial evaluating the effects of treatment with bright light therapy. A person-oriented cluster analysis was applied to study treatment effects in subgroups. Results. For the merged group, sleepiness (Epworth Sleepiness Scale, fatigue (fatigue questionnaire, and health-related quality of life (SF-36 were improved at posttreatment, and results were maintained at the one-month followup. Three distinct subgroups had a high level of fatigue in common, while the level of excessive daytime sleepiness and depressed mood differed between the subgroups. Over time, all subgroups improved following ten days treatment in a light room. Conclusion. Fatigue, excessive daytime sleepiness, and health-related quality of life improve in a similar way as depressed mood following treatment with bright light. The treatment was effective irrespective of the severity of the disorder, that is, for persons with SAD and subsyndromal SAD.

  9. Cleaning insertions and collimation challenges

    CERN Document Server

    Redaelli, S; Bertarelli, A; Bruce, R; Jowett, J M; Lechner, A; Losito, R

    2015-01-01

    High-performance collimation systems are essential for operating efficiently modern hadron machine with large beam intensities. In particular, at the LHC the collimation system ensures a clean disposal of beam halos in the superconducting environment. The challenges of the HL-LHC study pose various demanding requests for beam collimation. In this paper we review the present collimation system and its performance during the LHC Run 1 in 2010–2013. Various collimation solutions under study to address the HL-LHC requirements are then reviewed, identifying the main upgrade baseline and pointing out advanced collimation concept for further enhancement of the performance.

  10. Changes to the Transfer Line Collimation System for the High-Luminosity LHC Beams

    CERN Document Server

    Kain, V; Bracco, C; Fraser, M; Galleazzi, F; Gianfelice-Wendt, E; Kosmicki, A; Maciariello, F; Meddahi, M; Nuiry, F X; Steele, G; Velotti, F

    2015-01-01

    The current LHC transfer line collimation system will not be able to provide enough protection for the high brightness beams in the high-luminosity LHC era. The new collimation system will have to attenuate more and be more robust than its predecessor. The active jaw length of the new transfer line collimators will therefore be 2.1 m instead of currently 1.2 m. The transfer line optics will have to be adjusted for the new collimator locations and larger beta functions at the collimators for absorber robustness reasons. In this paper the new design of the transfer line collimation system will be presented with its implications on transfer line optics and powering, maintainability, protection of transfer line magnets in case of beam loss on a collimator and protection of the LHC aperture.

  11. There is nothing paranormal about near-death experiences: how neuroscience can explain seeing bright lights, meeting the dead, or being convinced you are one of them.

    Science.gov (United States)

    Mobbs, Dean; Watt, Caroline

    2011-10-01

    Approximately 3% of Americans declare to have had a near-death experience. These experiences classically involve the feeling that one's soul has left the body, approaches a bright light and goes to another reality, where love and bliss are all encompassing. Contrary to popular belief, research suggests that there is nothing paranormal about these experiences. Instead, near-death experiences are the manifestation of normal brain function gone awry, during a traumatic, and sometimes harmless, event.

  12. Adjunctive Triple Chronotherapy (Combined Total Sleep Deprivation, Sleep Phase Advance, and Bright Light Therapy) Rapidly Improves Mood and Suicidality in Suicidal Depressed Inpatients: An Open Label Pilot Study

    OpenAIRE

    Sahlem, Gregory L.; Kalivas, Benjamin; Fox, James B.; Lamb, Kayla; Roper, Amanda; Williams, Emily N.; Williams, Nolan R.; Korte, Jeffrey E.; Zuschlag, Zachary D.; El Sabbagh, Salim; Guille, Constance; Barth, Kelly S.; Uhde, Thomas W.; George, Mark S.; Short, E. Baron

    2014-01-01

    Previous studies have demonstrated that combined total sleep deprivation (Wake therapy), sleep phase advance, and bright light therapy (Triple Chronotherapy) produce a rapid and sustained antidepressant effect in acutely depressed individuals. To date no studies have explored the impact of the intervention on unipolar depressed individuals with acute concurrent suicidality. Participants were suicidal inpatients (N=10, Mean age=44±16.4SD, 6F) with unipolar depression. In addition to standard o...

  13. COLLIMATORS AND MATERIALS FOR HIGH INTENSITY HEAVY ION SYNCHROTRONS

    CERN Document Server

    Stadlmann, J; Kollmus, H; Spiller, P; Strasik, I; Tahir, N A; Tomut, M; Trautmann, C

    2012-01-01

    The operation of high power high brightness accelerators requires huge efforts for beam cleaning and machine protection. Within the WP 8 (ColMat) of the EU research framework EuCARD[1] we investigate new materials and methods for beam collimation and machine protection. We present an overview of these activities at the GSI Helmholtzzentrum f¨ur Schwerionenforschung, Darmstadt. Simulations of accidental beam losses in LHC and SIS100 have been performed. Scenarios for halo collimation of heavy ions and protons in SIS100 routine operation have been investigated. A prototype of a cryogenic collimator for charge exchange losses during intermediate charge state heavy ion operation in SIS100 has been build and tested with beam. Several candidates of advanced composite materials for collimation system upgrades of present and future high power accelerators have been irradiated and their properties are being characterized. Most deliverables and milestones of the R&D programme were already reached before the end of...

  14. High power collimated diode laser stack

    Institute of Scientific and Technical Information of China (English)

    LIU Yuan-yuan; FANG Gao-zhan; MA Xiao-yu; LIU Su-ping; FENG Xiao-ming

    2006-01-01

    A high power collimated diode laser stack is carried out based on fast-axis collimation and stack packaging techniques.The module includes ten typical continuous wave (cw) bars and the total output power can be up to 368W at 48.6A.Using a cylindrical lens as the collimation elements,we can make the fast-axis divergence and the slow-axis divergence are 0.926 40 and 8.2060 respectively.The light emitting area is limited in a square area of 18.3 mm×11 mm.The module has the advantage of high power density and offers a wide potential applications in pumping and material processing.

  15. A polymer based miniature loop heat pipe with silicon substrate and temperature sensors for high brightness light-emitting diodes

    NARCIS (Netherlands)

    Ye, H.; Sokolovskij, R.; Zeijl, H.W. van; Gielen, A.W.J.; Zhang, G.

    2014-01-01

    Solid State Lighting (SSL) systems, powered by light-emitting diodes (LEDs), are revolutionizing the lighting industry with energy saving and enhanced performance compared to traditional light sources. However, around 70%-80% of the electric power will still be transferred to heat. As the elevated t

  16. Photonic crystals for broadband, omnidirectional self-collimation

    Science.gov (United States)

    Chuang, Y.-C.; Suleski, T. J.

    2011-03-01

    In this paper, multiple photonic crystal (PC) structures are proposed to improve three-dimensional (3D) self-collimation performance, including two 3D PCs (tetragonal lattice structures and a complex hexagonal lattice structure) and two two-dimensional (2D) PCs (triangular lattice structures and kagome lattice structures) with out-of-plane orientation. Different design strategies are investigated and compared in terms of the resulting self-collimation performance. Several desired 3D properties are numerically realized for the first time, including broadband 3D self-collimation, omnidirectional beam confinement and broadband omnidirectional self-collimation. These developments can enable future self-collimation applications, such as multiplexers, PC core fibers and solar light collection.

  17. [Influence of collimation system on static Fourier transform spectrometer].

    Science.gov (United States)

    Jiang, Cheng-Zhi; Liang, Jing-Qiu; Liang, Zhong-Zhu; Sun, Qiang; Wang, Wei-Biao

    2014-01-01

    Collimation system provides collimated light for the static Fourier-transform spectroscopy (SFTS). Its quality is crucial to the signal to noise ratio (SNR) of SFTS. In the present paper, the physical model of SFTS was established based on the Fresnel diffraction theory by means of numerical software. The influence of collimation system on the SFTS was discussed in detail focusing on the aberrations of collimation lens and the quality of extended source. The results of simulation show that the influences of different kinds of aberrations on SNR take on obvious regularity, and in particular, the influences of off-axis aberrations on SNR are closely related to the location of off-axis point source. Finally the extended source's maximum radius allowed was obtained by simulation, which equals to 0.65 mm. The discussion results will be used for the design of collimation system.

  18. Collimation Cleaning at the LHC with Advanced Secondary Collimator Materials

    CERN Document Server

    AUTHOR|(CDS)2085459; Bruce, Roderik; Mereghetti, Alessio; Redaelli, Stefano; Rossi, A

    2015-01-01

    The LHC collimation system must ensure efficient beam halo cleaning in all machine conditions. The first run in 2010-2013 showed that the LHC performance may be limited by collimator material-related concerns, such as the contribution from the present carbon-based secondary collimators to the machine impedance and, consequently, to the beam instability. Novel materials based on composites are currently under development for the next generation of LHC collimators to address these limitations. Particle tracking simulations of collimation efficiency were performed using the Sixtrack code and a material database updated to model these composites. In this paper, the simulation results will be presented with the aim of studying the effect of the advanced collimators on the LHC beam cleaning.

  19. Fabrication of high-brightness GaN-based light-emitting diodes via thermal nanoimprinting of ZnO-nanoparticle-dispersed resin

    International Nuclear Information System (INIS)

    Highlights: • A various high-refractive-index ZnO patterns were formed on LED using imprinting. • Mechanism of light extraction enhancement was demonstrated by simulation and EL. • Light output power of patterned LED was improved up 19.6% by light waveguide effect. - Abstract: We fabricated high-brightness GaN-based light-emitting diodes (LEDs) with highly refractive patterned structures by using a thermal nanoimprint lithography (NIL). A highly refractive ZnO-nanoparticle-dispersed resin (ZNDR) was used in NIL, and a submicron hole, a submicron high-aspect-ratio pillar, and microconvex arrays were fabricated on the indium tin oxide (ITO) top electrode of GaN-based LED devices. We analyzed the light extraction mechanism for each of the three types of patterns by using a finite element method simulation, and found that the high-aspect-ratio pillar had a great ability to improve light extraction owing to its waveguide effect and prominent scattering effect. As a result, the light output power, which was measured in an integrating sphere, of the LED device was enhanced by up to 19.6% when the high-aspect-ratio pillar array was formed on the top ITO electrode of the device. Further, the electrical properties of none of the patterned LED devices fabricated using ZNDR degraded in comparison to those of bare LED devices

  20. Fabrication of high-brightness GaN-based light-emitting diodes via thermal nanoimprinting of ZnO-nanoparticle-dispersed resin

    Energy Technology Data Exchange (ETDEWEB)

    Byeon, Kyeong-Jae [Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109 (United States); Cho, Joong-Yeon; Jo, Han-Byeol [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Lee, Heon, E-mail: heonlee@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-701 (Korea, Republic of)

    2015-08-15

    Highlights: • A various high-refractive-index ZnO patterns were formed on LED using imprinting. • Mechanism of light extraction enhancement was demonstrated by simulation and EL. • Light output power of patterned LED was improved up 19.6% by light waveguide effect. - Abstract: We fabricated high-brightness GaN-based light-emitting diodes (LEDs) with highly refractive patterned structures by using a thermal nanoimprint lithography (NIL). A highly refractive ZnO-nanoparticle-dispersed resin (ZNDR) was used in NIL, and a submicron hole, a submicron high-aspect-ratio pillar, and microconvex arrays were fabricated on the indium tin oxide (ITO) top electrode of GaN-based LED devices. We analyzed the light extraction mechanism for each of the three types of patterns by using a finite element method simulation, and found that the high-aspect-ratio pillar had a great ability to improve light extraction owing to its waveguide effect and prominent scattering effect. As a result, the light output power, which was measured in an integrating sphere, of the LED device was enhanced by up to 19.6% when the high-aspect-ratio pillar array was formed on the top ITO electrode of the device. Further, the electrical properties of none of the patterned LED devices fabricated using ZNDR degraded in comparison to those of bare LED devices.

  1. Beam Cleaning and Collimation Systems

    CERN Document Server

    Redaelli, S

    2016-01-01

    Collimation systems in particle accelerators are designed to dispose of unavoidable losses safely and efficiently during beam operation. Different roles are required for different types of accelerator. The present state of the art in beam collimation is exemplified in high-intensity, high-energy superconducting hadron colliders, like the CERN Large Hadron Collider (LHC), where stored beam energies reach levels up to several orders of magnitude higher than the tiny energies required to quench cold magnets. Collimation systems are essential systems for the daily operation of these modern machines. In this document, the design of a multistage collimation system is reviewed, taking the LHC as an example case study. In this case, unprecedented cleaning performance has been achieved, together with a system complexity comparable to no other accelerator. Aspects related to collimator design and operational challenges of large collimation systems are also addressed.

  2. Dependence on the incident light power of the internal electric fields in a GaAs p-i-n solar cell according to bright photoreflectance spectroscopy

    Science.gov (United States)

    Jo, Hyun-Jun; Mun, Young Hee; Kim, Jong Su; Lee, Sang Jun

    2016-07-01

    Bright photoreflectance (BPR) spectroscopy at room temperature is used to examine the internal electric fields in a GaAs p-i-n solar cell for their dependence on the incident light power. Electric fields are observed at 30 µW and 100 µW of incident light. With increasing power, the strengths of the two electric fields are reduced due to the photovoltage effect. The electric field observed at 30 µW is assigned to the p-i interface, which is close to the surface. The other electric field is due to the i-n interface because the incident light penetrates deeper as the light power is increased. The electric field strength of 35.6 kV/cm at the p-i interface is lower than that of 42.9 kV/cm at the i-n interface at 500 µW of light power because the photovoltage effect is proportional to the number of photo-generated carriers, which is reduced as the distance from the surface increases. When the incident light power is similar to the excitation beam power, the electric fields at the p-i interface are saturated.

  3. Can the season of birth risk factor for schizophrenia be prevented by bright light treatment for the second trimester mother around the winter solstice?

    Science.gov (United States)

    Schwartz, Paul J

    2014-12-01

    The season of birth risk factor for schizophrenia exerts a pervasive effect on the global population, particularly at northerly latitudes. The winter infection hypothesis and the low vitamin D hypothesis are both compelling but lack conclusive clinical data. The present work develops a maternal-fetal chronobiological hypothesis for this season of birth risk factor and its prevention by maternal bright light treatment. Around the winter solstice, due to decreased sunlight, the chronobiological apparatus of the at-risk second trimester mother is characterized by a reduced amplitude circadian pacemaker, and a reduced maximum of her nocturnal plasma melatonin concentrations (MTmax) and an increased minimum of her nocturnal core body temperatures (Tmin)--both of which exert adverse effects on the fetal hippocampus and dorsal striatum. The consequences for the fetus include reduced volume and increased excitability of the hippocampus, ventral striatal dysfunction, increased presynaptic nigrostriatal dopamine transmission, and increased propensity for pathological nigrostriatal neuronal phasic firing. Thus, the maternal-fetal chronobiological hypothesis fully accounts for the fetal precursors of the major pathognomonic abnormalities in adults with schizophrenia. Bright light treatment for the second trimester mother around the winter solstice, by increasing maternal circadian amplitude, could possibly prevent the fetal hippocampal and striatal abnormalities and eliminate the season of birth risk factor for schizophrenia. PMID:25456791

  4. The formation and transformation of the spatial weak-light bright and dark solitons in a quantum dot molecule with the interdot tunneling coupling

    Science.gov (United States)

    Zeng, Kuanhong; Wang, Denglong; She, Yanchao; Luo, Xiaoqin

    2013-11-01

    We study analytically the properties of the optical absorption and the spatial weak-light solitons in a quantum dot molecule system with the interdot tunneling coupling (ITC). It is shown that, for the linear case, there exists tunneling induced transparency (TIT) in the context of a weak ITC, while the TIT can be replaced by Autler-Townes splitting in the presence of a strong ITC. For the nonlinear case, it is probable to realize the spatial optical solitons even under weak light intensity. Interestingly, we find that there appears transformation behavior between the bright and dark solitons by properly turning both the ITC strength and the detuning of the probe field. Meanwhile, the transformation condition of the bright and dark solitons is obtained. Additionally it is also found that the amplitude of the solitons first descends and then rises with the increasing of ITC strength. Our results may have potential applications for nonlinear optical experiments and optical telecommunication engineering in solid systems.

  5. Cavity Light-Emitting Diode for Durable, High-Brightness and High-Efficiency Lighting Applications: First Budget Period Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Yijian Shi

    2009-09-30

    A COLED device consists of a top electrode (anode) and a bottom electrode (cathode) separated by a thin dielectric layer. In this metal/dielectric stack, numerous small wells, or cavities, are etched through the top electrode and the dielectric layer. These cavities are subsequently filled with LEP molecules. When a voltage is applied between the top and bottom electrodes, holes (from the top electrode) and electrons (from the bottom electrode) are injected into the polymer. Light emission is generated upon recombination of holes and electrons within the polymer along the perimeters of cavities. Figure 1 compares the structures of the COLED and the traditional OLED. The existing COLED fabrication process flow is illustrated in Figure 2. A COLED can potentially be 5 times more efficient and can operate at as much as 100 times higher current density with much longer lifetime than an OLED. To fully realize these potential advantages, the COLED technology must overcome the following technical barriers, which were the technical focused points for Years 1 and 2 (Phase I) of this project: (1) Construct optimum thickness dielectric layer: In the traditional OLED structure, the optimal thickness of the LEP film is approximately 80-100 nm. In a COLED device, the effective LEP thickness roughly equals the thickness of the dielectric layer. Therefore, the optimal dielectric thickness for a COLED should also be roughly equal to 80-100 nm. Generally speaking, it is technically challenging to produce a defect-free dielectric layer at this thickness with high uniformity, especially over a large area. (2) Develop low-work-function cathode: A desired cathode should have a low work function that matches the lowest unoccupied molecular orbital (LUMO) level of the LEP molecules. This is usually achieved by using a low-work-function metal such as calcium, barium, lithium, or magnesium as the cathode. However, these metals are very vulnerable to oxygen and water. Since the cathode of the

  6. Brightness variation distributions among main belt asteroids from sparse light-curve sampling with Pan-STARRS 1

    Science.gov (United States)

    McNeill, A.; Fitzsimmons, A.; Jedicke, R.; Wainscoat, R.; Denneau, L.; Vereš, P.; Magnier, E.; Chambers, K. C.; Kaiser, N.; Waters, C.

    2016-07-01

    The rotational state of asteroids is controlled by various physical mechanisms including collisions, internal damping and the Yarkovsky-O'Keefe-Radzievskii-Paddack effect. We have analysed the changes in magnitude between consecutive detections of ˜60 000 asteroids measured by the Panoramic Survey Telescope and Rapid Response System (PanSTARRS) 1 survey during its first 18 months of operations. We have attempted to explain the derived brightness changes physically and through the application of a simple model. We have found a tendency towards smaller magnitude variations with decreasing diameter for objects of 1 < D < 8 km. Assuming the shape distribution of objects in this size range to be independent of size and composition our model suggests a population with average axial ratios 1 : 0.85 ± 0.13 : 0.71 ± 0.13, with larger objects more likely to have spin axes perpendicular to the orbital plane.

  7. Brightness variation distributions among main belt asteroids from sparse light curve sampling with Pan-STARRS 1

    CERN Document Server

    McNeill, A; Jedicke, R; Wainscoat, R; Denneau, L; Veres, P; Magnier, E; Chambers, K C; Kaiser, N; Waters, C

    2016-01-01

    The rotational state of asteroids is controlled by various physical mechanisms including collisions, internal damping and the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. We have analysed the changes in magnitude between consecutive detections of approximately 60,000 asteroids measured by the PanSTARRS 1 survey during its first 18 months of operations. We have attempted to explain the derived brightness changes physically and through the application of a simple model. We have found a tendency toward smaller magnitude variations with decreasing diameter for objects of 1 < D < 8 km. Assuming the shape distribution of objects in this size range to be independent of size and composition our model suggests a population with average axial ratios 1 : 0.85 \\pm 0.13 : 0.71 \\pm 0.13, with larger objects more likely to have spin axes perpendicular to the orbital plane.

  8. Adjunctive triple chronotherapy (combined total sleep deprivation, sleep phase advance, and bright light therapy) rapidly improves mood and suicidality in suicidal depressed inpatients: an open label pilot study.

    Science.gov (United States)

    Sahlem, Gregory L; Kalivas, Benjamin; Fox, James B; Lamb, Kayla; Roper, Amanda; Williams, Emily N; Williams, Nolan R; Korte, Jeffrey E; Zuschlag, Zachary D; El Sabbagh, Salim; Guille, Constance; Barth, Kelly S; Uhde, Thomas W; George, Mark S; Short, E Baron

    2014-12-01

    Previous studies have demonstrated that combined total sleep deprivation (Wake therapy), sleep phase advance, and bright light therapy (Triple Chronotherapy) produce a rapid and sustained antidepressant effect in acutely depressed individuals. To date no studies have explored the impact of the intervention on unipolar depressed individuals with acute concurrent suicidality. Participants were suicidal inpatients (N = 10, Mean age = 44 ± 16.4 SD, 6F) with unipolar depression. In addition to standard of care, they received open label Triple Chronotherapy. Participants underwent one night of total sleep deprivation (33-36 h), followed by a three-night sleep phase advance along with four 30-min sessions of bright light therapy (10,000 lux) each morning. Primary outcome measures included the 17 item Hamilton depression scale (HAM17), and the Columbia Suicide Severity Rating Scale (CSSRS), which were recorded at baseline prior to total sleep deprivation, and at protocol completion on day five. Both HAM17, and CSSRS scores were greatly reduced at the conclusion of the protocol. HAM17 scores dropped from a mean of 24.7 ± 4.2 SD at baseline to a mean of 9.4 ± 7.3 SD on day five (p = .002) with six of the ten individuals meeting criteria for remission. CSSRS scores dropped from a mean of 19.5 ± 8.5 SD at baseline to a mean of 7.2 ± 5.5 SD on day five (p = .01). The results of this small pilot trial demonstrate that adjunctive Triple Chronotherapy is feasible and tolerable in acutely suicidal and depressed inpatients. Limitations include a small number of participants, an open label design, and the lack of a comparison group. Randomized controlled studies are needed. PMID:25231629

  9. The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-Time Observations, First-Light Time, Distance to NGC 4666, and Progenitor Constraints

    CERN Document Server

    Shappee, B J; Holoien, T W -S; Prieto, J L; Contreras, C; Itagaki, K; Burns, C R; Kochanek, C S; Stanek, K Z; Alper, E; Basu, U; Beacom, J F; Bersier, D; Brimacombe, J; Conseil, E; Danilet, A B; Dong, Subo; Falco, E; Grupe, D; Hsiao, E Y; Kiyota, S; Morrell, N; Nicolas, J; Phillips, M M; Pojmanski, G; Simonian, G; Stritzinger, M; Szczygieł, D M; Thompson, T A; Thorstensen, J; Wagner, M; Woźniak, P R

    2015-01-01

    On 2014 Dec. 9.61, the All-Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin") discovered ASASSN-14lp just $\\sim2$ days after first light using a global array of 14-cm diameter telescopes. ASASSN-14lp went on to become a bright supernova ($V = 11.94$ mag), second only to SN 2014J for the year. We present prediscovery photometry (with a detection less than a day after first light) and ultraviolet through near-infrared photometric and spectroscopic data covering the rise and fall of ASASSN-14lp for more than 100 days. We find that ASASSN-14lp had a broad light curve ($\\Delta m_{15}(B) = 0.796 \\pm 0.001_{\\textrm{stat}}$), a $B$-band maximum at $2457015.823 \\pm 0.030_{\\textrm{stat}}$, a rise time of $16.94^{+ 0.11 }_{- 0.11 }$ days, and moderate host--galaxy extinction ($E(B-V)_{\\textrm{host}} = 0.329 \\pm 0.001_{\\textrm{stat}}$). Using ASASSN-14lp we derive a distance modulus for NGC 4666 of $\\mu = 30.834 \\pm 0.003_{\\textrm{stat}} \\pm 0.16_{\\textrm{syst}}$ corresponding to a distance of $14.68 \\pm 0.02_{\\...

  10. A double-blind randomized controlled trial to assess the effect of bright light therapy on depression in patients with Parkinson’s disease

    Directory of Open Access Journals (Sweden)

    Sonja Rutten

    2016-10-01

    Full Text Available Abstract Background A disturbed circadian rhythm seems to be a causal factor in the occurrence of depressive disorders in patients with Parkinson’s disease (PD. The circadian rhythm can be restored with light. Therefore, Bright Light Therapy (BLT might be a new treatment option for depression in PD patients. Methods/design In this double-blind controlled trial, 84 subjects with idiopathic PD are randomized to either BLT or a control light condition. The BLT condition emits white light with an intensity of 10,000 Lux, while the control device emits dim white light of 200 Lux, which is presumed to be too low to influence the circadian rhythm. Subjects receive 30 min of home treatment twice daily for three months. Timing of treatment is based on the individual chronotype. After finishing treatment, subjects enter a follow-up period of six months. The primary outcome of the study is the severity of depressive symptoms, as measured with the Hamilton Depression Rating Scale. Secondary outcomes are alternative depression measures, objective and subjective sleep measures, and salivary melatonin and cortisol concentrations. For exploratory purposes, we also assess the effects on motor symptoms, global cognitive function, comorbid psychiatric disorders, quality of life and caregiver burden. Data will be analyzed using a linear mixed models analysis. Discussion Performing a placebo-controlled trial on the effects of BLT in PD patients is challenging, as the appearance of the light may provide clues on the treatment condition. Moreover, fixed treatment times lead to an improved sleep-wake rhythm, which also influences the circadian system. With our study design, we do not compare BLT to placebo treatment, i.e. an ineffective control treatment. Rather, we compare structuring of the sleep-wake cycle in both conditions with additional BLT in the experimental condition, and additional dim light in the control condition. Participants are not informed about

  11. Low-intensity blue-enriched white light (750 lux and standard bright light (10 000 lux are equally effective in treating SAD. A randomized controlled study

    Directory of Open Access Journals (Sweden)

    Bos Elske H

    2011-01-01

    Full Text Available Abstract Background Photoreceptor cells containing melanopsin play a role in the phase-shifting effects of short-wavelength light. In a previous study, we compared the standard light treatment (SLT of SAD with treatment using short-wavelength blue-enriched white light (BLT. Both treatments used the same illuminance (10 000 lux and were equally highly effective. It is still possible, however, that neither the newly-discovered photoreceptor cells, nor the biological clock play a major role in the therapeutic effects of light on SAD. Alternatively, these effects may at least be partly mediated by these receptor cells, which may have become saturated as a result of the high illuminances used in the therapy. This randomized controlled study compares the effects of low-intensity BLT to those of high-intensity SLT. Method In a 22-day design, 22 patients suffering from a major depression with a seasonal pattern (SAD were given light treatment (10 000 lux for two weeks on workdays. Subjects were randomly assigned to either of the two conditions, with gender and age evenly distributed over the groups. Light treatment either consisted of 30 minutes SLT (5000°K with the EnergyLight® (Philips, Consumer Lifestyle with a vertical illuminance of 10 000 lux at eye position or BLT (17 000°K with a vertical illuminance of 750 lux using a prototype of the EnergyLight® which emitted a higher proportion of short-wavelengths. All participants completed questionnaires concerning mood, activation and sleep quality on a daily basis. Mood and energy levels were also assessed on a weekly basis by means of the SIGH-SAD and other assessment tools. Results On day 22, SIGH-SAD ratings were significantly lower than on day 1 (SLT 65.2% and BLT 76.4%. On the basis of all assessments no statistically significant differences were found between the two conditions. Conclusion With sample size being small, conclusions can only be preliminary. Both treatment conditions were found

  12. Collimation: a silicon solution

    CERN Multimedia

    2007-01-01

    Silicon crystals could be used very efficiently to deflect high-energy beams. Testing at CERN has produced conclusive results, which could pave the way for a new generation of collimators. The set of five crystals used to test the reflection of the beams. The crystals are 0.75 mm wide and their alignment is adjusted with extreme precision. This figure shows the deflection of a beam by channelling and by reflection in the block of five crystals. Depending on the orientation of the crystals: 1) The beam passes without "seeing" the crystals and is not deflected 2) The beam is deflected by channelling (with an angle of around 100 μrad) 3) The beam is reflected (with an angle of around 50 μrad). The intensity of the deflected beam is illustrated by the intensity of the spot. The spot of the reflected beam is clearly more intense than that one of the channelled beam, demonstrating the efficiency of t...

  13. High-brightness beamline for x-ray spectroscopy at the ALS

    Energy Technology Data Exchange (ETDEWEB)

    Perera, R.C.C.; Jones, G. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States); Lindle, D.W. [Univ. of Nevada, Las Vegas, NV (United States)

    1997-04-01

    Beamline 9.3.1 at the Advanced Light Source (ALS) is a windowless beamline, covering the 1-6 keV photon-energy range, designed to achieve the goals of high energy resolution, high flux, and high brightness at the sample. When completed later this year, it will be the first ALS monochromatic hard x-ray beamline, and its brightness will be an order of magnitude higher than presently available in this energy range. In addition, it will provide flux and resolution comparable to any other beamline now in operation. To achieve these goals, two technical improvements, relative to existing x-ray beamlines, were incorporated. First, a somewhat novel optical design for x-rays, in which matched toroidal mirrors are positioned before and after the double-crystal monochromator, was adopted. This configuration allows for high resolution by passing a collimated beam through the monochromator, and for high brightness by focusing the ALS source on the sample with unit magnification. Second, a new {open_quotes}Cowan type{close_quotes} double-crystal monochromator based on the design used at NSLS beamline X-24A was developed. The measured mechanical precision of this new monochromator shows significant improvement over existing designs, without using positional feedback available with piezoelectric devices. Such precision is essential because of the high brightness of the radiation and the long distance (12 m) from the source (sample) to the collimating (focusing) mirror. This combination of features will provide a bright, high resolution, and stable x-ray beam for use in the x-ray spectroscopy program at the ALS.

  14. Efficient Dielectric Metasurface Collimating Lenses for Mid-Infrared Quantum Cascade Lasers

    OpenAIRE

    Arbabi, Amir; Briggs, Ryan M.; Horie, Yu; Bagheri, Mahmood; Faraon, Andrei

    2015-01-01

    Light emitted from single-mode semiconductor lasers generally has large divergence angles, and high numerical aperture lenses are required for beam collimation. Visible and near infrared lasers are collimated using aspheric glass or plastic lenses, yet collimation of mid-infrared quantum cascade lasers typically requires more costly aspheric lenses made of germanium, chalcogenide compounds, or other infrared-transparent materials. Here we report mid-infrared dielectric metasurface flat lenses...

  15. Quantum communication with macroscopically bright nonclassical states.

    Science.gov (United States)

    Usenko, Vladyslav C; Ruppert, Laszlo; Filip, Radim

    2015-11-30

    We analyze homodyne detection of macroscopically bright multimode nonclassical states of light and propose their application in quantum communication. We observe that the homodyne detection is sensitive to a mode-matching of the bright light to the highly intense local oscillator. Unmatched bright modes of light result in additional noise which technically limits detection of Gaussian entanglement at macroscopic level. When the mode-matching is sufficient, we show that multimode quantum key distribution with bright beams is feasible. It finally merges the quantum communication with classical optical technology of visible beams of light. PMID:26698776

  16. New method for improving angle measurement precision of laser collimation system under complex background

    Science.gov (United States)

    Zhao, Xiaofeng; Chen, He; Tan, Lilong; Zhang, Zhili; Cai, Wei

    2014-09-01

    We have proposed a new method for improving angle measurement precision based on the principle of CCD laser collimation in this paper. First, through the control of the laser's state, on or off, by the Digital Signal Processor (DSP), the collimation light and the background light can be sampled, individually. Second, with the comparison between the sampled value of the background light intensity and the threshold value which has been set in the DSP previously, the DSP can automatically control Complex Programmable Logic Device (CPLD) to adjust the light integral time of CCD to adapt to different environment background and the changeable scanning driver of CCD is realized. Last, by the digital wave filtering the impact of the background light on the collimation light can be removed. With the comprehensive application of the controlling technology of automatically changeable scanning driving, collimation light on or off, A/D conversion and adaptive filtering, the integration time of the collimation system can automatically adjust to the proper value according to the change of the environment and the impact of the background light on the collimation system can be well removed. The simulation results show that the new method can achieve the self-adaptable control with the change of the environment and can improve the measurement precision of the laser collimation system under the complex environment.

  17. Enhanced luminous efficiency and brightness using DNA electron blocking layers in bio-organic light emitting diodes

    Science.gov (United States)

    Hagen, Joshua A.

    The biopolymer deoxyribonucleic acid (DNA) has been extracted from salmon (saDNA) and used successfully as an electron blocking layer (EBL) in multiple structures of Organic Light Emitting Diodes (OLED). Water soluble saDNA was complexed with a cationic surfactant hexadecytrimethylammonium chloride (CTMA) which makes the resulting DNA-CTMA molecule water insoluble, and soluble in common organic media such as alcohols. Solutions of DNA-CTMA and butanol make uniform thin films from 20nm to 5 microns in thickness by varying spin coating parameters and molecular weight. The optical properties of DNA-CTMA thin films include high transparency and low optical loss for applications at wavelengths above 400nm. The DNA-CTMA films have an electrical resistivity on the order of 107 O*cm. All of these properties combined made DNA-CTMA a candidate as an EBL in OLEDs, and this resulting device was termed a Bio-organic Light Emitting Diode (BioLED). Enhanced electroluminescent efficiency has been demonstrated in both green and blue emitting BioLEDs. The resulting green and blue BioLEDs showed a maximum luminous efficiency of 8.2 and 0.8 cd/A, respectively. The DNA based BioLEDs were as much as 10x more efficient and 30x brighter than their OLED counterparts. The enhancement in performance is due to the electron blocking action with the 0.9 eV (lowest unoccupied molecular orbital) value, allows hole injection to proceed with a 5.6eV (highest occupied molecular orbital) value. DNA-CTMA has also been successfully deposited in thin film form via molecular beam deposition (MBD). The growth was achieved at 160°C at vacuum levels of 10-5 Torr at a deposition rate of 0.8A/s. MBD grown DNA-CTMA thin films were highly uniform, optically transparent, and adhere to silicon, quartz and glass substrates more strongly than spin coated films. The material deposited was verified as DNA-CTMA through optical absorption, energy dispersive X-ray analysis, and using a DNA indicating fluorescent dye

  18. Design and experimental validation of a compact collimated Knudsen source

    CERN Document Server

    Wouters, Steinar H W; Mutsaers, Peter H A; Vredenbregt, Edgar J D

    2015-01-01

    In this paper we discuss the design and performance of a collimated Knudsen source which has the benefit of a simple design over recirculating sources. Measurements of the flux, transverse velocity distribution and brightness at different temperatures were conducted to evaluate the performance. The scaling of the flux and brightness with the source temperature follow the theoretical predictions. The transverse velocity distribution in the transparent operation regime also agrees with the simulated data. The source was found able to produce a flux of $10^{14}$ s$^{-1}$ at a temperature of 433 K. Furthermore the transverse reduced brightness of an ion beam with equal properties as the atomic beam reads $1.7 \\times 10^2$ A/(m${}^2$ sr eV) which is sufficient for our goal: the creation of an ultra-cold ion beam by ionization of a laser-cooled and compressed atomic rubidium beam.

  19. The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-time Observations, First-light Time, Distance to NGC 4666, and Progenitor Constraints

    Science.gov (United States)

    Shappee, B. J.; Piro, A. L.; Holoien, T. W.-S.; Prieto, J. L.; Contreras, C.; Itagaki, K.; Burns, C. R.; Kochanek, C. S.; Stanek, K. Z.; Alper, E.; Basu, U.; Beacom, J. F.; Bersier, D.; Brimacombe, J.; Conseil, E.; Danilet, A. B.; Dong, Subo; Falco, E.; Grupe, D.; Hsiao, E. Y.; Kiyota, S.; Morrell, N.; Nicolas, J.; Phillips, M. M.; Pojmanski, G.; Simonian, G.; Stritzinger, M.; Szczygieł, D. M.; Taddia, F.; Thompson, T. A.; Thorstensen, J.; Wagner, M. R.; Woźniak, P. R.

    2016-08-01

    On 2014 December 9.61, the All-sky Automated Survey for SuperNovae (ASAS-SN or “Assassin”) discovered ASASSN-14lp just ˜2 days after first light using a global array of 14 cm diameter telescopes. ASASSN-14lp went on to become a bright supernova (V = 11.94 mag), second only to SN 2014J for the year. We present prediscovery photometry (with a detection less than a day after first light) and ultraviolet through near-infrared photometric and spectroscopic data covering the rise and fall of ASASSN-14lp for more than 100 days. We find that ASASSN-14lp had a broad light curve ({{Δ }}{m}15(B)=0.80+/- 0.05), a B-band maximum at 2457015.82 ± 0.03, a rise time of {16.94}-0.10+0.11 days, and moderate host-galaxy extinction (E{(B-V)}{host}=0.33+/- 0.06). Using ASASSN-14lp, we derive a distance modulus for NGC 4666 of μ =30.8+/- 0.2, corresponding to a distance of 14.7 ± 1.5 Mpc. However, adding ASASSN-14lp to the calibrating sample of Type Ia supernovae still requires an independent distance to the host galaxy. Finally, using our early-time photometric and spectroscopic observations, we rule out red giant secondaries and, assuming a favorable viewing angle and explosion time, any nondegenerate companion larger than 0.34 {R}⊙ .

  20. Fermilab Recycler Collimation System Design

    Energy Technology Data Exchange (ETDEWEB)

    Brown, B. C. [Fermilab; Adamson, P. [Fermilab; Ainsworth, R. [Fermilab; Capista, D. [Fermilab; Hazelwood, K. [Fermilab; Kourbanis, I. [Fermilab; Mokhov, N. V. [Fermilab; Morris, D. K. [Fermilab; Murphy, M. [Fermilab; Sidorov, V. [Fermilab; Stern, E. [Fermilab; Tropin, I. [Fermilab; Yang, M-J. [Fermilab

    2016-10-04

    To provide 700 kW proton beams for neutrino production in the NuMI facility, we employ slip stacking in the Recycler with transfer to the Main Injector for recapture and acceleration. Slip stacking with 12 Booster batches per 1.33 sec cycle of the Main Injector has been implemented and briefly tested while extensive operation with 8 batches and 10 batches per MI cycle has been demonstrated. Operation in this mode since 2013 shows that loss localization is an essential component for long term operation. Beam loss in the Recycler will be localized in a collimation region with design capability for absorbing up to 2 kW of lost protons in a pair of 20-Ton collimators (absorbers). This system will employ a two stage collimation with a thin molybdenum scattering foil to define the bottom edge of both the injected and decelerated-for-slipping beams. Optimization and engineering design of the collimator components and radiation shielding are based on comprehensive MARS15 simulations predicting high collimation efficiency as well as tolerable levels of prompt and residual radiation. The system installation during the Fermilab 2016 facility shutdown will permit commissioning in the subsequent operating period.

  1. Efficient Dielectric Metasurface Collimating Lenses for Mid-Infrared Quantum Cascade Lasers

    CERN Document Server

    Arbabi, Amir; Horie, Yu; Bagheri, Mahmood; Faraon, Andrei

    2015-01-01

    Light emitted from single-mode semiconductor lasers generally has large divergence angles, and high numerical aperture lenses are required for beam collimation. Visible and near infrared lasers are collimated using aspheric glass or plastic lenses, yet collimation of mid-infrared quantum cascade lasers typically requires more costly aspheric lenses made of germanium, chalcogenide compounds, or other infrared-transparent materials. Here we report mid-infrared dielectric metasurface flat lenses that efficiently collimate the output beam of single-mode quantum cascade lasers. The metasurface lenses are composed of amorphous silicon posts on a flat sapphire substrate and can be fabricated at low cost using a single step conventional UV binary lithography. Mid-infrared radiation from a 4.8 $\\mu$m distributed-feedback quantum cascade laser is collimated using a polarization insensitive metasurface lens with 0.86 numerical aperture and 79% transmission efficiency. The collimated beam has a half divergence angle of 0...

  2. Transverse Impedance of LHC Collimators

    CERN Document Server

    Métral, E; Assmann, Ralph Wolfgang; Boccardi, A; Bracco, C; Bohl, T; Caspers, Friedhelm; Gasior, M; Jones, O R; Kasinski, K; Kroyer, T; Redaelli, S; Robert-Demolaize, R; Roncarolo, F; Rumolo, G; Salvant, B; Steinhagen, R; Weiler, T; Zimmermann, F

    2007-01-01

    The transverse impedance in the LHC is expected to be dominated by the numerous collimators, most of which are made of Fibre-Reinforced-Carbon to withstand the impacts of high intensity proton beams in case of failures, and which will be moved very close to the beam, with full gaps of few millimetres, in order to protect surrounding super-conducting equipments. We present an estimate of the transverse resistive-wall impedance of the LHC collimators, the total impedance in the LHC at injection and top energy, the induced coupled-bunch growth rates and tune shifts, and finally the result of the comparison of the theoretical predictions with measurements performed in 2004 and 2006 on a prototype collimator installed in the SPS.

  3. Collimation with hollow electron beams

    CERN Document Server

    Stancari, G; Annala, G; Kuznetsov, G; Shiltsev, V; Still, D A; Vorobiev, L G

    2011-01-01

    A novel concept of controlled halo removal for intense high-energy beams in storage rings and colliders is presented. It is based on the interaction of the circulating beam with a 5-keV, magnetically confined, pulsed hollow electron beam in a 2-m-long section of the ring. The electrons enclose the circulating beam, kicking halo particles transversely and leaving the beam core unperturbed. By acting as a tunable diffusion enhancer and not as a hard aperture limitation, the hollow electron beam collimator extends conventional collimation systems beyond the intensity limits imposed by tolerable losses. The concept was tested experimentally at the Fermilab Tevatron proton-antiproton collider. The first results on the collimation of 980-GeV antiprotons are presented.

  4. First cleaning with LHC collimators

    CERN Document Server

    Wollmann, D; Arnau-Izquiedo, G; Assmann, R; Bacher, J P; Baglin, V; Bellodi, G; Bertarelli, A; Bouzoud, A; Bracco, C; Bruce, R; Brugger, M; Calatroni, S; Cerruti, F; Chamizo, R; Cherif, A; Chiaveri, E; Chiggiato, P; Dallochio, A; Dehning, B; Donze, M; Ferrari, A; Folch, R; Francon, P; Gander, P; Geisser, J M; Grudiev, A; Holzer, EB; Jacquet, D; Jeanneret, J B; Jimenez, J M; Jonker, M; Jowett, J; Kershaw, K; Lari, L; Lendaro, J; Loprete, F; Losito, R; Magistris, M; Malabaila, M; Mayer, M; Marsili, A; Masi, A; Mathot, S; Métral, E; Mitifiot, C; Mounet, N; de Morais Amaral, R; Nordt, A; Perret, R; Perrollaz, S; Rathjen, C; Redaelli, S; Robert-Demolaize, G; Roesler, S; Rossi, A; Salvant, B; Santana, M; Sexton, I; Sievers, P; Tardy, T; Timmins, M; Tsoulou, K; Veyrunes, E; Vincke, H; Vlachoudis, V; Vuillemin, V; Weiler, T; Zimmermann, F; Baishev, I; Kurochkin, I; Kaltchev, D; Caspers, F; Kadi, Y

    2010-01-01

    The LHC has two dedicated cleaning insertions: IR3 for momentum cleaning and IR7 for betatron cleaning. The collimation system has been specified and built with tight mechanical tolerances (e.g. jaw flatness ~ 40 μm ) and is designed to achieve a high accuracy and reproducibility of the jaw positions (~ 20 μm). The practically achievable cleaning efficiency of the present Phase-I system depends on the precision of the jaw centering around the beam, the accuracy of the gap size and the jaw parallelism against the beam. The reproducibility and stability of the collimation system is important to avoid the frequent repetition of beam based alignment which is currently a lengthy procedure. Within this paper we describe the method used for the beam based alignment of the LHC collimation system, its achieved accuracy and stability and its performance at 450GeV.

  5. Bright white-light emission from Ag/SiO2/CdS-ZnS core/shell/shell plasmon couplers.

    Science.gov (United States)

    Liao, Chen; Tang, Luping; Gao, Xiaoqin; Xu, Ruilin; Zhang, Huichao; Yu, Yongya; Lu, Changgui; Cui, Yiping; Zhang, Jiayu

    2015-12-28

    Well-defined plasmon couplers (PCs) that comprise a Ag core overcoated with a SiO(2) shell with controlled thickness, followed by a monolayer of CdS-ZnS core-shell quantum dots (QDs) were synthesized to modify the emission from trap-rich CdS-ZnS QDs by adjusting the distance between the QDs and Ag nanoparticles (NPs). When the thickness of the SiO(2) shell was 10 nm, because the shell could effectively suppress the non-radiative energy transfer from the semiconductor QDs to the metal NPs and the localized surface plasmon resonance (LSPR) of the Ag NPs spectrally matched the emission peak of the CdS-ZnS QDs to bring about strong plasmon coupling, optimum enhancements of the surface state emission (SSE) (17 times) and band-edge emission (BEE) (4 times) were simultaneously realized and the SSE to BEE intensity ratio was increased to 55%. As a result, a bright white-light source with 1931 Commission Internationale d'Eclairage (CIE) chromaticity coordinates of (0.32, 0.34) was realized by the superposition of the two emissions. The experimental results from Ag/SiO(2)/CdSe-ZnS and the Ag/SiO(2)/CdS:Mn-ZnS core/shell/shell PCs indicated that suppressing the non-radiative decay rate (k(nr)) was the underlying mechanism for plasmon coupling fluorescence enhancement. PMID:26592756

  6. Research on the Inactivation Effect of Pulsed Bright Light to Bacillus subtilis in water%脉冲强光对水中枯草杆菌灭活效果的研究

    Institute of Scientific and Technical Information of China (English)

    赵伟; 马玉坤

    2014-01-01

    Pulsed bright light sterilization technology developed in recent years is a new type of cold steriliza-tion technique with strong white light flashes for sterilization. This paper compares inactivation effect of pulsed bright light and UV with Bacillus subtilis as target microorganism. By changing input voltage and frequency of light flashes, effect factors of pulsed bright light sterilization is studied.%脉冲强光杀菌技术是近年来开发的一种新型冷杀菌技术,利用强烈的白光闪照进行杀菌。以枯草杆菌为目标微生物,对比研究脉冲强光与紫外线对微生物的灭活效果。并通过改变脉冲强光装置的输入电压和闪照次数,研究了影响脉冲强光杀菌的影响因素。

  7. A neutron collimator with adjustable radiation field

    International Nuclear Information System (INIS)

    An adjustable neutron collimator for neutron therapy purposes is described. The collimator is designed to give a very sharp radiation field and a high freedom of choice for the radiation geometrics. (L.E.)

  8. Collimator with attachment mechanism and system

    Science.gov (United States)

    Kross, Brian J.; McKisson, John; Stolin, Aleksandr; Weisenberger, Andrew G.; Zorn, Carl

    2012-07-10

    A self-aligning collimator for a radiation imaging device that is secured and aligned through the use of a plurality of small magnets. The collimator allows for the rapid exchange, removal, or addition of collimators for the radiation imaging device without the need for tools. The accompanying method discloses the use of magnets and accompanying magnetic fields to align and secure collimators in a radiation imaging assembly.

  9. Carbon nanotube collimator fabrication and application

    Science.gov (United States)

    Chow, Lee; Chai, Guangyu; Schenkel, Thomas

    2010-07-06

    Apparatus, methods, systems and devices for fabricating individual CNT collimators. Micron size fiber coated CNT samples are synthesized with chemical vapor deposition method and then the individual CNT collimators are fabricated with focused ion beam technique. Unfocused electron beams are successfully propagated through the CNT collimators. The CNT nano-collimators are used for applications including single ion implantation and in high-energy physics, and allow rapid, reliable testing of the transmission of CNT arrays for transport of molecules.

  10. The brightness of colour.

    Directory of Open Access Journals (Sweden)

    David Corney

    Full Text Available BACKGROUND: The perception of brightness depends on spatial context: the same stimulus can appear light or dark depending on what surrounds it. A less well-known but equally important contextual phenomenon is that the colour of a stimulus can also alter its brightness. Specifically, stimuli that are more saturated (i.e. purer in colour appear brighter than stimuli that are less saturated at the same luminance. Similarly, stimuli that are red or blue appear brighter than equiluminant yellow and green stimuli. This non-linear relationship between stimulus intensity and brightness, called the Helmholtz-Kohlrausch (HK effect, was first described in the nineteenth century but has never been explained. Here, we take advantage of the relative simplicity of this 'illusion' to explain it and contextual effects more generally, by using a simple Bayesian ideal observer model of the human visual ecology. We also use fMRI brain scans to identify the neural correlates of brightness without changing the spatial context of the stimulus, which has complicated the interpretation of related fMRI studies. RESULTS: Rather than modelling human vision directly, we use a Bayesian ideal observer to model human visual ecology. We show that the HK effect is a result of encoding the non-linear statistical relationship between retinal images and natural scenes that would have been experienced by the human visual system in the past. We further show that the complexity of this relationship is due to the response functions of the cone photoreceptors, which themselves are thought to represent an efficient solution to encoding the statistics of images. Finally, we show that the locus of the response to the relationship between images and scenes lies in the primary visual cortex (V1, if not earlier in the visual system, since the brightness of colours (as opposed to their luminance accords with activity in V1 as measured with fMRI. CONCLUSIONS: The data suggest that perceptions

  11. Fluorescence-guided surgery of retroperitoneal-implanted human fibrosarcoma in nude mice delays or eliminates tumor recurrence and increases survival compared to bright-light surgery.

    Directory of Open Access Journals (Sweden)

    Fuminari Uehara

    Full Text Available The aim of this study is to determine if fluorescence-guided surgery (FGS can eradicate human fibrosarcoma growing in the retroperitoneum of nude mice. One week after retroperitoneal implantation of human HT1080 fibrosarcoma cells, expressing green fluorescent protein (GFP (HT-1080-GFP, in nude mice, bright-light surgery (BLS was performed on all tumor-bearing mice (n = 22. After BLS, mice were randomized into 2 treatment groups; BLS-only (n = 11 or the combination of BLS + FGS (n = 11. The residual tumors remaining after BLS were resected with FGS using a hand-held portable imaging system under fluorescence navigation. The average residual tumor area after BLS + FGS was significantly smaller than after BLS-only (0.4 ± 0.4 mm(2 and 10.5 ± 2.4 mm(2, respectively; p = 0.006. Five weeks after surgery, the fluorescent-tumor areas of BLS- and BLS + FGS-treated mice were 379 ± 147 mm(2 and 11.7 ± 6.9 mm(2, respectively, indicating that FGS greatly inhibited tumor recurrence compared to BLS. The combination of BLS + FGS significantly decreased fibrosarcoma recurrence compared to BLS-only treated mice (p < 0.001. Mice treated with BLS+FGS had a significantly higher disease-free survival rate than mice treated with BLS-only at five weeks after surgery. These results suggest that combination of BLS + FGS significantly reduced the residual fibrosarcoma volume after BLS and improved disease-free survival.

  12. Research on Most Appropriate Brightness of Projection and Ambient Light in Multimedia Classroom%最适投影照度与教室环境光照度的关系研究

    Institute of Scientific and Technical Information of China (English)

    刘连; 刘敏; 杨帆; 贺丽; 刘雪莲; 胡又农

    2014-01-01

    探究最适投影照度与多媒体教室环境光照度的关系,发现在一定照度范围内,最适投影照度与教室环境光照度的差是一个固定值。该关系可以给投影机的使用、采购和多媒体教室的设计提供数据指导。%This research explored the relationship between the most appropriate brightness of projection screen and ambient light in multimedia classroom. Result shows that in a certain illumination range, the difference between the most appropriate brightness of projection screen and the ambient light is a fixed value, which affords data guidance to the use and purchase of projections and multimedia classroom design.

  13. Comparison of effects of bright light therapy alone or combined with fluoxetine on severity of depression, circadian rhythms, mood disturbance, and sleep quality, in patients with non-seasonal depression

    OpenAIRE

    Ağargün MY; Hızlı Sayar G; Bulut H; Tan O

    2013-01-01

    Mehmet Yücel Agargün,1 Gokben Hizli Sayar,2 Hüseyin Bulut,3 Oguz Tan21Medipol University, Department of Psychiatry, Istanbul, Turkey; 2Uskudar University, Neuropsychiatry Istanbul Hospital, Istanbul, Turkey; 3Büyükçekmece Government Hospital, Department of Psychiatry, Istanbul, TurkeyPurpose: To compare effects of bright light therapy (BLT) alone or combined with the selective serotonin reuptake inhibitor (SSRI) fluoxetine, on severity of depression, circadian ...

  14. Comparison of effects of bright light therapy alone or combined with fluoxetine on severity of depression, circadian rhythms, mood disturbance, and sleep quality, in patients with non-seasonal depression

    OpenAIRE

    Hizli Sayar, Gökben

    2013-01-01

    Mehmet Yücel Agargün,1 Gokben Hizli Sayar,2 Hüseyin Bulut,3 Oguz Tan21Medipol University, Department of Psychiatry, Istanbul, Turkey; 2Uskudar University, Neuropsychiatry Istanbul Hospital, Istanbul, Turkey; 3Büyükçekmece Government Hospital, Department of Psychiatry, Istanbul, TurkeyPurpose: To compare effects of bright light therapy (BLT) alone or combined with the selective serotonin reuptake inhibitor (SSRI) fluoxetine, on severity o...

  15. High resolution alpha particle spectrometry through collimation

    International Nuclear Information System (INIS)

    Alpha particle spectrometry with collimation is a useful method for identifying nuclear materials among various nuclides. A mesh type collimator reduces the low energy tail and broadened energy distribution by cutting off particles with a low incidence angle. The relation between the resolution and the counting efficiency can be investigated by changing a ratio of the mesh hole diameter and the collimator thickness. Through collimation, a target particle can be distinguished by a PIPS® detector under a mixture of various nuclides. - Highlights: • Alpha particle spectrometry with collimation a useful method for identifying nuclear materials among various radionuclides. • A collimator cut off alpha particles with low angle emitted from a source. • We confirm that that a collimator improves the resolution of alpha spectra through both simulation and experiments

  16. Fano resonance of self-collimated beams in two-dimensional photonic crystals.

    Science.gov (United States)

    Lee, Sun-Goo; Park, Jong-Moon; Kee, Chul-Sik

    2014-11-17

    We report that the Fano resonance of self-collimated beams can be achieved in a two-dimensional photonic crystal by introducing a Fano resonator that is composed of zigzag line defects. An asymmetric Fano line shape in a transmission spectrum is generated by the interference between radiated light beams from the resonator and self-collimated beams that directly pass through the resonator without resonance. It is shown that the Fano profile increases in sharpness as the number of zigzag line defects increases because the phase values of the radiated light beams change more rapidly when the number of defects increases. The Fano resonance of self-collimated beams could provide an efficient approach to manipulate light propagation and increase the possibility of application of self-collimated beams. PMID:25402134

  17. Neutron collimator with rectangular beam profile

    Energy Technology Data Exchange (ETDEWEB)

    Cussen, L.D. E-mail: leo.cussen@vu.edu.au; Hoeghoj, P.; Anderson, I.S

    2001-03-21

    Several Soller slit-type neutron collimators which give rectangular profiles of transmission as a function of angular divergence have been constructed. The collimators accept a beam of realistic dimensions - greater than 12x22 mm{sup 2} in all cases. The blades of the collimators are 280 {mu}m thick wafers of single-crystal silicon each coated with a Ni-Gd-Ni multilayer on one side. Tests at a neutron wavelength of 7.5 A confirm that the transmission profiles are rectangular. Tests at a wavelength of 4.2 A show that two such collimators rocked against each other give dramatically enhanced transmission and resolution by comparison with conventional collimators. This is the first such demonstration of increased counting rates in a scan on an instrument from rectangular profile collimators, an effect expected but not produced for over 40 years.

  18. Neutron collimator with rectangular beam profile

    CERN Document Server

    Cussen, L D; Anderson, I S

    2001-01-01

    Several Soller slit-type neutron collimators which give rectangular profiles of transmission as a function of angular divergence have been constructed. The collimators accept a beam of realistic dimensions - greater than 12x22 mm sup 2 in all cases. The blades of the collimators are 280 mu m thick wafers of single-crystal silicon each coated with a Ni-Gd-Ni multilayer on one side. Tests at a neutron wavelength of 7.5 A confirm that the transmission profiles are rectangular. Tests at a wavelength of 4.2 A show that two such collimators rocked against each other give dramatically enhanced transmission and resolution by comparison with conventional collimators. This is the first such demonstration of increased counting rates in a scan on an instrument from rectangular profile collimators, an effect expected but not produced for over 40 years.

  19. Neutron collimator with rectangular beam profile

    International Nuclear Information System (INIS)

    Several Soller slit-type neutron collimators which give rectangular profiles of transmission as a function of angular divergence have been constructed. The collimators accept a beam of realistic dimensions - greater than 12x22 mm2 in all cases. The blades of the collimators are 280 μm thick wafers of single-crystal silicon each coated with a Ni-Gd-Ni multilayer on one side. Tests at a neutron wavelength of 7.5 A confirm that the transmission profiles are rectangular. Tests at a wavelength of 4.2 A show that two such collimators rocked against each other give dramatically enhanced transmission and resolution by comparison with conventional collimators. This is the first such demonstration of increased counting rates in a scan on an instrument from rectangular profile collimators, an effect expected but not produced for over 40 years

  20. PLEIADES: High Peak Brightness, Subpicosecond Thomson Hard-X-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Kuba, J; Anderson, S G; Barty, C J; Betts, S M; Booth, R; Brown, W J; Crane, J K; Cross, R R; Fittinghoff, D N; Gibson, D J; Harteman, F V; Le Sage, G P; Rosenzweig, J B; Tremaine, A M; Springer, P T

    2003-12-15

    The Picosecond Laser-Electron Inter-Action for the Dynamic Evaluation of Structures (PLEIADES) facility, is a unique, novel, tunable (10-200 keV), ultrafast (ps-fs), hard x-ray source that greatly extends the parameter range reached by existing 3rd generation sources, both in terms of x-ray energy range, pulse duration, and peak brightness at high energies. First light was observed at 70 keV early in 2003, and the experimental data agrees with 3D codes developed at LLNL. The x-rays are generated by the interaction of a 50 fs Fourier-transform-limited laser pulse produced by the TW-class FALCON CPA laser and a highly focused, relativistic (20-100 MeV), high brightness (1 nC, 0.3-5 ps, 5 mm.mrad, 0.2% energy spread) photo-electron bunch. The resulting x-ray brightness is expected to exceed 10{sup 20} ph/mm{sup 2}/s/mrad{sup 2}/0.1% BW. The beam is well-collimated (10 mrad divergence over the full spectrum, 1 mrad for a single color), and the source is a unique tool for time-resolved dynamic measurements in matter, including high-Z materials.

  1. Polarization Beam Splitter Based on Self-Collimation of a Hybrid Photonic Crystal

    Directory of Open Access Journals (Sweden)

    F. Bagci

    2014-12-01

    Full Text Available A photonic crystal polarization beam splitter based on photonic band gap and self-collimation effects is designed for optical communication wavelengths. The photonic crystal structure consists of a polarization-insensitive self-collimation region and a splitting region. TM- and TE-polarized waves propagate without diffraction in the self-collimation region, whereas they split by 90 degrees in the splitting region. Efficiency of more than 75% for TM- and TE-polarized light is obtained for a polarization beam splitter size of only 17 μm x 17 μm in a wavelength interval of 60 nm including 1.55 μm.

  2. Beam halo collimation in heavy ion synchrotrons

    Science.gov (United States)

    Strašík, I.; Prokhorov, I.; Boine-Frankenheim, O.

    2015-08-01

    This paper presents a systematic study of the halo collimation of ion beams from proton up to uranium in synchrotrons. The projected Facility for Antiproton and Ion Research synchrotron SIS100 is used as a reference case. The concepts are separated into fully stripped (e.g., 238U92+ ) and partially stripped (e.g., 238U28+ ) ion collimation. An application of the two-stage betatron collimation system, well established for proton accelerators, is intended also for fully stripped ions. The two-stage system consists of a primary collimator (a scattering foil) and secondary collimators (bulky absorbers). Interaction of the particles with the primary collimator (scattering, momentum losses, and nuclear interactions) was simulated by using fluka. Particle-tracking simulations were performed by using mad-x. Finally, the dependence of the collimation efficiency on the primary ion species was determined. The influence of the collimation system adjustment, lattice imperfections, and beam parameters was estimated. The concept for the collimation of partially stripped ions employs a thin stripping foil in order to change their charge state. These ions are subsequently deflected towards a dump location using a beam optical element. The charge state distribution after the stripping foil was obtained from global. The ions were tracked by using mad-x.

  3. Out of the darkness and into the light: bright field in situ hybridisation for delineation of ERBB2 (HER2) status in breast carcinoma

    OpenAIRE

    Gruver, Aaron M; Peerwani, Ziad; Tubbs, Raymond R.

    2010-01-01

    Assessment of ERBB2 (HER2) status in breast carcinomas has become critical in determining response to the humanised monoclonal antibody trastuzumab. The current joint College of American Pathologists and the American Society of Clinical Oncology guidelines for the evaluation of HER2 status in breast carcinoma involve testing by immunohistochemistry and fluorescence in situ hybridisation (FISH). However, neither of these modalities is without limitations. Novel bright field in situ hybridisati...

  4. The UBVRI light curve behaviour of the Seyfert galaxy NGC 4151 during the extraordinary maximum of the nuclear brightness in 1989-1997

    Science.gov (United States)

    Merkulova, N. I.

    Observations were carried out with the 1.25 m telescope of Crimean Astrophysical Observatory, equipped with a Double Image Chopping Photometer--Polarimeter by Prof. V.Piirola from Helsinki University. This device allows to obtain simultaneous observations in 5 filters of Johnson's UBVRI system. Photometric errors were less than 0,m01, time resolution was about 3--4 min. Round diaphragms with diameters 20 and 15 arcseconds were used. During this extraordinary maximum the nuclear brightness in the U band increases on ~2m.0, while in the I band -- only on ~ 0m.7. All colour indices decreased: (U-B) from ~-0m.3 to ~-0m.8, (B-V) from ~0m.9 to ~0m.4, (V-I) from ~1m.3 to ~0m.9. The flux ascending in the blue spectral region was twice more than in the red one. The galaxy nucleus seems to be more and more "bluer", but some brightness and colour variations were observed during each of the 9 observational seasons, include local mimimums, flares and intranight variability. Colour--magnitude dependences were analyzed as well as two--colour diagrams. There were no differences between data obtained in 20" and 15" apertures. This fact means that we can see only fluxes from the galactic nucleus during the epoch of brightness maximum.

  5. Modeling of a multileaf collimator

    Science.gov (United States)

    Kim, Siyong

    A comprehensive physics model of a multileaf collimator (MLC) field for treatment planning was developed. Specifically, an MLC user interface module that includes a geometric optimization tool and a general method of in- air output factor calculation were developed. An automatic tool for optimization of MLC conformation is needed to realize the potential benefits of MLC. It is also necessary that a radiation therapy treatment planning (RTTP) system is capable of modeling MLC completely. An MLC geometric optimization and user interface module was developed. The planning time has been reduced significantly by incorporating the MLC module into the main RTTP system, Radiation Oncology Computer System (ROCS). The dosimetric parameter that has the most profound effect on the accuracy of the dose delivered with an MLC is the change in the in-air output factor that occurs with field shaping. It has been reported that the conventional method of calculating an in-air output factor cannot be used for MLC shaped fields accurately. Therefore, it is necessary to develop algorithms that allow accurate calculation of the in-air output factor. A generalized solution for an in-air output factor calculation was developed. Three major contributors of scatter to the in-air output-flattening filter, wedge, and tertiary collimator-were considered separately. By virtue of a field mapping method, in which a source plane field determined by detector's eye view is mapped into a detector plane field, no additional dosimetric data acquisition other than the standard data set for a range of square fields is required for the calculation of head scatter. Comparisons of in-air output factors between calculated and measured values show a good agreement for both open and wedge fields. For rectangular fields, a simple equivalent square formula was derived based on the configuration of a linear accelerator treatment head. This method predicts in-air output to within 1% accuracy. A two

  6. Characterisation of fan-beam collimators.

    Science.gov (United States)

    Pareto, D; Pavía, J; Falcón, C; Juvells, I; Cot, A; Ros, D

    2001-02-01

    Fan-beam collimators offer a good balance between resolution and noise. The collimator response may be included in iterative reconstruction algorithms in order to improve single-photon emission tomography (SPET) resolution. To this end, accurate determination of the focal region and characterisation of the collimator response as a function of the source co-ordinates must be performed. In this paper, a method to characterise fanbeam collimators is evaluated. First, we calculated the real focal region and the accuracy of the collimator convergence. Then, we confirmed the hypothesis that Gaussian distributions adequately fit the collimator responses, although no individualised treatment was performed for the tails of detector response which are associated with scattering and septal penetration. Finally, analytical functions were used to model the resolution and sensitivity. The parameter values in these functions were obtained from experimental measures by non-linear regression fitting. Our findings show differences of 1.43% between nominal and real focal length and standard deviations of 2.5 mm in the x-direction and 7.1 mm in the y-direction for the focal convergence. The correlation coefficients between experimental and predicted values were 0.994 for resolution and 0.991 for sensitivity. As a consequence, the proposed method can be used to characterise the collimator response.

  7. Characterisation of fan-beam collimators

    International Nuclear Information System (INIS)

    Fan-beam collimators offer a good balance between resolution and noise. The collimator response may be included in iterative reconstruction algorithms in order to improve single-photon emission tomography (SPET) resolution. To this end, accurate determination of the focal region and characterisation of the collimator response as a function of the source co-ordinates must be performed. In this paper, a method to characterise fan-beam collimators is evaluated. First, we calculated the real focal region and the accuracy of the collimator convergence. Then, we confirmed the hypothesis that Gaussian distributions adequately fit the collimator responses, although no individualised treatment was performed for the tails of detector response which are associated with scattering and septal penetration. Finally, analytical functions were used to model the resolution and sensitivity. The parameter values in these functions were obtained from experimental measures by non-linear regression fitting. Our findings show differences of 1.43% between nominal and real focal length and standard deviations of 2.5 mm in the x-direction and 7.1 mm in the y-direction for the focal convergence. The correlation coefficients between experimental and predicted values were 0.994 for resolution and 0.991 for sensitivity. As a consequence, the proposed method can be used to characterise the collimator response. (orig.)

  8. Lensless CCD-based fluorometer using a micromachined optical Soller collimator

    NARCIS (Netherlands)

    Balsam, Joshua; Ossandon, Miguel; Kostov, Yordan; Bruck, Hugh Alan; Rasooly, Avraham

    2011-01-01

    In this paper, we describe a simple charge-coupled device (CCD) based lensless fluorometer with sensitivity in the range of current ELISA plate readers. In our lensfree fluorometer, a multi-wavelength LED light source was used for fluorophore excitation. To collimate the light, we developed a simple

  9. Collimator for the SPS extracted beam

    CERN Multimedia

    1976-01-01

    This is a water cooled copper collimator (TCSA) which has exactly the shape of the cross section of the downstream magnetic beam splitter. Parts of the blown up primary proton beam pass above/below and left through this collimator. A small part of the protons is absorbed in the thin copper wedges. In this way the downstream magnetic splitter of the same cross section receives already a beam where its magnetic wedges are no longer hit by protons. The upstream, water cooled collimator, more resistant to protons, has cast a 'shadow' onto the downstream magnetic splitter, less resistant to protons. Gualtero Del Torre stands on the left.

  10. Scrapping and Collimation Tests in the SPS

    CERN Document Server

    Fischer, C; Jung, R; CERN. Geneva. AB Department

    2004-01-01

    Scraping of the SPS beam will be required prior to extraction towards the LHC in order to remove the beam tails and ensure clean injection conditions. Scraper mechanisms recuperated from the ISR and collimators coming from LEP are installed since a few years in the SPS to test this concept. The purpose of these tests was to show that with the help of the associated two stage collimation system, it is possible to make the scraping process very clean by confining the losses at the collimator locations, hence without irradiating any other part of the machine.

  11. Crystal Collimation with protons at injection energy

    CERN Document Server

    Rossi, Roberto; Masi, Alessandro; Mirarchi, Daniele; Montesano, Simone; Redaelli, Stefano; Valentino, Gianluca; Scandale, Walter; CERN. Geneva. ATS Department

    2015-01-01

    During this MD, performed on August 30th, 2015, bent silicon crystals were tested with protons beams for a possible usage of crystal-assisted collimation. Tests were performed at injection energy, using both horizontal and vertical crystals, providing a crucial test of the hardware for precise crystal angle adjustments (goniometers). Proton channeling was observed for the first time with LHC beams and the channeled beams were probed with scans performed with secondary collimators. Measurements of cleaning efficiency of a crystal-based collimation system were also performed.

  12. The HEAO-1 Scanning Modulation Collimator

    Science.gov (United States)

    Schwartz, Daniel A.

    2013-01-01

    My niche on this panel seems to be the High Energy Astronomy Observatory-1 Scanning Modulation Collimator experiment. Our chair, Hale Bradt, and the late Herb Gursky each proposed a different version modulation collimator, which was condensed by NASA via "forced marriage," to the SMC. I worked as Project Scientist under Herb, later inheriting the PI role. The MIT Project Scientist, the late Rodger Doxsey, and I were told "this is your experiment," and "we are a seamless team regardless of institution." Rodger and I were young enough to believe this, and we made it happen (and not always with the best results vis a vis higher internal management). I was never interested in astronomy, and allegedly am still not. Why do an astro-metrical job of measuring and reporting the coordinates of X-ray sources? In fact we participated widely in the identification of the sources with astronomical object, and making each paper a discussion of the physics of the emission. An enjoyable way to learn some astronomy. The stated purpose of the Gursky/Bradt experiment was to enable optical identifications so that more detailed study could be done. I remember meeting with John Whelan to discuss his collaboration in making the optical identifications. He said he only wanted to study sources after they were identified. For many milliseconds I became very angry - "who is going to to the work to MAKE those identifications," but luckily before speaking I realized how satisfying it was that astronomers indeed wanted to study X-ray sources in other wavebands. The second biggest excitement in the HEAO-1 program was the "glitches" that appeared in the gyro data during final functional testing. This took some high-powered politics by all the PI's to convince MSFC to delay for 4 months, replacing the "funny" unit with one from HEAO-2 (Einstein) and later refurbishing that unit. Third biggest excitement was when a computer failed and final checkout during countdown at the Cape was done by looking at

  13. Burkina Faso - BRIGHT II

    Data.gov (United States)

    Millenium Challenge Corporation — Millennium Challenge Corporation hired Mathematica Policy Research to conduct an independent evaluation of the BRIGHT II program. The three main research questions...

  14. Self-collimation-based photonic crystal Mach–Zehnder demultiplexer

    Science.gov (United States)

    Lee, Sun-Goo; Jung, Soo-Yong; Lee, Jongjin; Park, Jong-Moon; Kee, Chul-Sik

    2016-09-01

    A photonic crystal Mach–Zehnder demultiplexer (PC-MZDmux) with four output ports based on the self-collimation phenomenon in a two-dimensional (2D) PC is proposed and numerically studied using finite-difference time-domain simulations. The PC-MZDmux is composed of three Mach–Zehnder interferometers (MZIs) and each MZI consists of two 50:50 beam splitters and two perfect mirrors. Employed as the design parameters to achieve the demultiplexing functionality are the radius of phase control rods (PCRs) in the mirrors and the distance between the beam spitter and the mirror in the three MZIs. From spatial electric field distributions and transmission spectra, it is demonstrated that an incident self-collimated beam with four different frequencies can be demultiplexed to four output ports of the PC-MZDmux with proper design parameters. Our results indicate that this device design may constitute an efficient approach to light propagation manipulation and increase the application range of self-collimated beams.

  15. Spatial Brightness Perception of Trichromatic Stimuli

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.; Houser, Kevin W.

    2012-11-16

    An experiment was conducted to examine the effect of tuning optical radiation on brightness perception for younger (18-25 years of age) and older (50 years of age or older) observers. Participants made forced-choice evaluations of the brightness of a full factorial of stimulus pairs selected from two groups of four metameric stimuli. The large-field stimuli were created by systematically varying either the red or the blue primary of an RGB LED mixture. The results indicate that light stimuli of equal illuminance and chromaticity do not appear equally bright to either younger or older subjects. The rank-order of brightness is not predicted by any current model of human vision or theory of brightness perception including Scotopic to Photopic or Cirtopic to Photopic ratio theory, prime color theory, correlated color temperature, V(λ)-based photometry, color quality metrics, linear brightness models, or color appearance models. Age may affect brightness perception when short-wavelength primaries are used, especially those with a peak wavelength shorter than 450 nm. The results suggest further development of metrics to predict brightness perception is warranted, and that including age as a variable in predictive models may be valuable.

  16. Using the Larval Zebrafish Locomotor Asssay in Functional Neurotoxicity Screening: Light Brightness and the Order of Stimulus Presentation Affect the Outcome

    Science.gov (United States)

    We are evaluating methods to screen/prioritize large numbers of chemicals using 6 day old zebrafish (Danio rerio) as an alternative model for detecting neurotoxic effects. Our behavioral testing paradigm simultaneously tests individual larval zebrafish under sequential light and...

  17. New methods of particle collimation in colliders

    CERN Document Server

    Stancari, Giulio

    2011-01-01

    The collimation system is an essential part of the design of any high-power accelerator. Its functions include protection of components from accidental and intentional energy deposition, reduction of backgrounds, and beam diagnostics. Conventional multi-stage systems based on scatterers and absorbers offer robust shielding and efficient collection of losses. Two complementary concepts have been proposed to address some of the limitations of conventional systems: channeling and volume reflection in bent crystals and collimation with hollow electron beams. The main focus of this paper is the hollow electron beam collimator, a novel concept based on the interaction of the circulating beam with a 5-keV, magnetically confined, pulsed hollow electron beam in a 2-m-long section of the ring. The electrons enclose the circulating beam, kicking halo particles transversely and leaving the beam core unperturbed. By acting as tunable diffusion enhancer and not as a hard aperture limitation, the hollow electron beam collim...

  18. Collimation of laser-produced proton beam

    Science.gov (United States)

    Takano, M.; Nagashima, T.; Izumiyama, T.; Gu, Y. J.; Barada, D.; Kong, Q.; Wang, P. X.; Ma, Y. Y.; Wang, W. M.; Kawata, S.

    2016-03-01

    In intense laser plasma interaction for particle acceleration several issues remain to be solved. In this paper we focus on a collimation of ion beam, which is produced by a laser plasma interaction. In this study, the ion beam is collimated by a thin film target. When an intense short pulse laser illuminates a target, target electrons are accelerated, and create an electron cloud that generates a sheath electric field at the target surface. Such the ion acceleration mechanism is called the target normal sheath acceleration (TNSA). The TNSA field would be used for the ion beam collimation by the electric field. We have successfully obtained a collimated beam in our particle-in-cell simulations.

  19. Digital chest radiography: collimation and dose reduction

    DEFF Research Database (Denmark)

    Debess, Jeanne; Johnsen, Karen Kirstine; Vejle-Sørensen, Jens Kristian;

    Purpose: Quality improvement of basic radiography focusing on collimation and dose reduction in digital chest radiography Methods and Materials:A retrospective study of digital chest radiography is performed to evaluate the primary x-ray tube collimation of the PA and lateral radiographs. Data from...... one hundred fifty self-reliant female patients between 15 and 55 years of age are included in the study. The clinical research is performed between September and November 2014 where 3rd year Radiography students collect data on four Danish x-ray departments using identical procedures under guidance...... of clinical supervisors. Optimal collimation is determined by European and Regional Danish guidelines. The areal between current and optimal collimation is calculated. The experimental research is performed in September - October 2014 Siemens Axiom Aristos digital radiography system DR using 150 kV, 1,25 -3...

  20. Semiautomatic beam-based LHC collimator alignment

    CERN Document Server

    Valentino, Gianluca; Bruce, Roderik; Wollmann, Daniel; Sammut, Nicholas; Rossi, Adriana; Redaelli, Stefano

    2012-01-01

    Full beam-based alignment of the LHC collimation system was a time-consuming procedure (up to 28 hours) as the collimators were set up manually. A yearly alignment campaign has been sufficient for now, although in the future due to tighter tolerances this may lead to a decrease in the cleaning efficiency if machine parameters such as the beam orbit drift over time. Automating the collimator setup procedure can reduce the beam time for collimator setup and allow for more frequent alignments, therefore reducing the risk of performance degradation. This article describes the design and testing of a semiautomatic algorithm as a first step towards a fully automatic setup procedure. The parameters used to measure the accuracy and performance of the alignment are defined and determined from experimental data. A comparison of these measured parameters at 450 GeV and 3.5 TeV with manual and semiautomatic alignment is provided.

  1. Observations and diagnostics in high brightness beams

    Science.gov (United States)

    Cianchi, A.; Anania, M. P.; Bisesto, F.; Castellano, M.; Chiadroni, E.; Pompili, R.; Shpakov, V.

    2016-09-01

    The brightness is a figure of merit largely used in the light sources, like FEL (Free Electron Lasers), but it is also fundamental in several other applications, as for instance Compton backscattering sources, beam driven plasma accelerators and THz sources. Advanced diagnostics are essential tools in the development of high brightness beams. 6D electron beam diagnostics will be reviewed with emphasis on emittance measurement.

  2. Comparison of carbon and HI-Z primary collimators for the LHC phase II collimation system

    CERN Document Server

    Keller, L; Smith, J; Assmann, R; Bracco, C; Weiler, T

    2010-01-01

    A current issue with the LHC collimation system is single-diffractive, off-energy protons from the primary collimators that pass completely through the secondary collimation system and are absorbed immediately downbeam in the cold magnets of the dispersion suppressor section. Simulations suggest that the high impact rate could result in quenching of these magnets. We have studied replacing the 60 cm primary graphite collimators, which remove halo mainly by inelastic strong interactions, with 5.25 mm tungsten, which remove halo mainly by multiple coulomb scattering and thereby reduce the rate of single-diffractive interactions that cause losses in the dispersion suppressor.

  3. Comparison of the current LHC Collimators and the SLAC Phase 2 Collimator Impedances

    CERN Document Server

    Day, Hugo; Metral, Elias; Salvant, Benoit; Jones, Roger

    2011-01-01

    One of the key sources of transverse impedance in the LHC has been the secondary graphite collimators that sit close to the beam at all energies. This limits the stable bunch intensity due to transverse coupled-bunch instabilities and transverse mode coupling instability. To counteract this, new secondary collimators have been proposed for the phase II upgrade of the LHC collimation system. A number of designs based on different jaw materials and mechanical designs have been proposed. A comparison of the beam coupling impedance of these different designs derived from simulations are presented, with reference to the existing phase I secondary collimator design.

  4. Comparison of the current LHC Collimators and the SLAC phase 2 Collimator impedances

    CERN Document Server

    Day, H A; Metral, E; Salvant, B; Jones, R M

    2011-01-01

    One of the key sources of transverse impedance in the LHC has been the secondary graphite collimators that sit close to the beam at all energies. This limits the stable bunch intensity due to transverse coupled-bunch instabilities and transverse mode coupling instability. To counteract this, new secondary collimators have been proposed for the phase II upgrade of the LHC collimation system. A number of designs based on different jaw materials and mechanical designs have been proposed. A comparison of the beam coupling impedance of these different designs derived from simulations are presented, with reference to the existing phase I secondary collimator design.

  5. A Simple and Inexpensive Collimator for Neutron Radiography

    DEFF Research Database (Denmark)

    Olsen, J.; Mortensen, L.

    1974-01-01

    A neutron beam collimator was constructed by means of plastic drinking “straws”. The properties of the collimator were investigated, and especially the distribution of the neutrons at different distances.......A neutron beam collimator was constructed by means of plastic drinking “straws”. The properties of the collimator were investigated, and especially the distribution of the neutrons at different distances....

  6. Efficient dielectric metasurface collimating lenses for mid-infrared quantum cascade lasers

    Science.gov (United States)

    Arbabi, Amir; Briggs, Ryan M.; Horie, Yu; Bagheri, Mahmood; Faraon, Andrei

    2015-12-01

    Light emitted from single-mode semiconductor lasers generally has large divergence angles, and high numerical aperture lenses are required for beam collimation. Visible and near infrared lasers are collimated using aspheric glass or plastic lenses, yet collimation of mid-infrared quantum cascade lasers typically requires more costly aspheric lenses made of germanium, chalcogenide compounds, or other infrared-transparent materials. Here we report mid-infrared dielectric metasurface flat lenses that efficiently collimate the output beam of single-mode quantum cascade lasers. The metasurface lenses are composed of amorphous silicon posts on a flat sapphire substrate and can be fabricated at low cost using a single step conventional UV binary lithography. Mid-infrared radiation from a 4.8 $\\mu$m distributed-feedback quantum cascade laser is collimated using a polarization insensitive metasurface lens with 0.86 numerical aperture and 79% transmission efficiency. The collimated beam has a half divergence angle of 0.36$^\\circ$ and beam quality factor of $M^2$=1.02.

  7. Efficient dielectric metasurface collimating lenses for mid-infrared quantum cascade lasers.

    Science.gov (United States)

    Arbabi, Amir; Briggs, Ryan M; Horie, Yu; Bagheri, Mahmood; Faraon, Andrei

    2015-12-28

    Light emitted from single-mode semiconductor lasers generally has large divergence angles, and high numerical aperture lenses are required for beam collimation. Visible and near infrared lasers are collimated using aspheric glass or plastic lenses, yet collimation of mid-infrared quantum cascade lasers typically requires more costly aspheric lenses made of germanium, chalcogenide compounds, or other infrared-transparent materials. Here we report mid-infrared dielectric metasurface flat lenses that efficiently collimate the output beam of single-mode quantum cascade lasers. The metasurface lenses are composed of amorphous silicon posts on a flat sapphire substrate and can be fabricated at low cost using a single step conventional UV binary lithography. Mid-infrared radiation from a 4.8 μm distributed-feedback quantum cascade laser is collimated using a polarization insensitive metasurface lens with 0.86 numerical aperture and 79% transmission efficiency. The collimated beam has a half divergence angle of 0.36° and beam quality factor of M2=1.02. PMID:26831996

  8. Experimental study of phase locking of fiber collimators using internal beam-tail interference

    Science.gov (United States)

    Beresnev, Leonid A.; Vorontsov, Mikhail A.; Weyrauch, Thomas; Carhart, Gary; Lachinova, Svetlana L.; Liu, Jiang

    2011-02-01

    Experimental study of internal phase locking of a seven fiber collimator array is presented. As a metric for the feedback loop the periphery areas (tails) of beams outgoing from three adjacent fiber tips are used before the beams are clipped by the lens apertures. The "intercepted" tails of beams are redirected back into the collimator array forming an interference pattern located between adjacent collimators. Optical energy from one region of the pattern is selected by a pinhole, detected with a photo-diode and used as a metric signal for an SPGD controller to lock the phase of the three adjacent beam tails. The non-common phase difference of the outgoing wavefronts from these three collimators can be manipulated by altering the position of the pinhole in focal plane of the interference pattern and is removed (set to "zero" or 2π increments) by a displacement selected to produce the expected far field interference pattern. To phase lock the beams from seven collimators arranged in a hexagonal array, three pinholes, each of which receives some light from the center collimator are used. A sum of the signals from the three photo-diodes placed behind these pinholes is used to lock the phase of the six periphery beams to the central uncontrolled reference without beam splitters or a remote target-in-theloop metric.

  9. Compact collimated fiber optic array diagnostic for railgun plasmas

    Science.gov (United States)

    Tang, V.; Solberg, J. M.; Ferriera, T. J.; Tully, L. K.; Stephan, P. L.

    2009-01-01

    We developed and tested a compact collimated 16 channel fiber optic array diagnostic for studying the light emission of railgun armature plasmas with approximately millimeter spatial and submicrosecond temporal resolution. The design and operational details of the diagnostic are described. Plasma velocities, oscillation, and dimension data from the diagnostic for the Livermore fixed hybrid armature experiment are presented and compared with one-dimensional simulations. The techniques and principles discussed allow the extension of the diagnostic to other railgun and related dense plasma experiments.

  10. Compact collimated fiber optic array diagnostic for railgun plasma experiments

    Energy Technology Data Exchange (ETDEWEB)

    Tang, V; Solberg, J; Ferriera, T; Tully, L; Stephan, P

    2008-10-02

    We have developed and tested a compact collimated sixteen channel fiber optic array diagnostic for studying the light emission of railgun armature plasmas with {approx}mm spatial and sub-{micro}s temporal resolution. The design and operational details of the diagnostic are described. Plasma velocities, oscillation, and dimension data from the diagnostic for the Livermore Fixed Hybrid Armature experiment are presented and compared with 1-D simulations. The techniques and principles discussed allow the extension of the diagnostic to other railgun and related dense plasma experiments.

  11. Robust Collimation Control of Laser-Generated Ion Beam

    OpenAIRE

    Kawata, S; Takano, M.; Kamiyama, D.; T. Nagashima; Barada, D.; Gu, Y. J.; Li, X; Yu, Q; Kong, Q.; Wang, P. X.

    2015-01-01

    The robustness of a structured collimation device is discussed for an intense-laser-produced ion beam. In this paper the ion beam collimation is realized by the solid structured collimation device, which produces the transverse electric field; the electric field contributes to reduce the ion beam transverse velocity and collimate the ion beam. Our 2.5 dimensional particle-in cell simulations demonstrate that the collimation device is rather robust against the changes in the laser parameters a...

  12. Sunspot Bright Points

    CERN Document Server

    Choudhary, Debi Prasad

    2010-01-01

    We used the flux calibrated images through the Broad Band Filter Imager and Stokes Polarimeter data obtained with the Solar Optical Telescope onboard the Hinode spacecraft to study the properties of bright points in and around the sunspots. The well isolated bright points were selected and classified as umbral dot, peripheral umbral dot, penumbral grains and G-band bright point depending on their location. Most of the bright points are smaller than about 150 km. The larger points are mostly associated with the penumbral features. The bright points are not uniformly distributed over the umbra but preferentially located around the penumbral boundary and in the fast decaying parts of umbra. The color temperature of the bright points, derived using the continuum irradiance, are in the range of 4600 K to 6600 K with cooler ones located in the umbra. The temperature increases as a function of distance from the center to outside. The G-band, CN-band and CaII H flux of the bright points as a function of their blue ba...

  13. High-brightness electron injectors

    International Nuclear Information System (INIS)

    Free-electron laser (FEL) oscillators and synchrotron light sources require pulse trains of high peak brightness and, in some applications, high-average power. Recent developments in the technology of photoemissive and thermionic electron sources in rf cavities for electron-linac injector applications offer promising advances over conventional electron injectors. Reduced emittance growth in high peak-current electron injectors may be achieved by using high field strengths and by linearizing the radial component of the cavity electric field at the expense of lower shunt impedance

  14. Vol. 31 - Crystal Collimation for LHC

    CERN Document Server

    Mirarchi, Daniele; Scandale, Walter; Hall, Geoffrey

    2015-01-01

    Future upgrades of the CERN Large Hadron Collider (LHC) may demand improved cleaning performance of its collimation system. Very efficient collimation is required during regular operations at high intensities, because even a small amount of energy deposited on superconducting magnets can cause an abrupt loss of superconducting conditions (quench). The present collimation system has accomplished its tasks during the LHC Run I very well, where no quench with circulating beam took place with up to 150 MJ of stored energy at 4 TeV. On the other hand, uncertainty remains on the performance at the design energy of 7 TeV and with 360 MJ of stored energy. In particular, a further increase up to about 700 MJ is expected for the high luminosity upgrade (HL-LHC), where improved cleaning performance may be needed together with a reduction of collimator impedance. The possibility to use a crystal-based collimation system represents an option for improving both cleaning performance and impedance compared to the present s...

  15. Upgrade scenario for the RHIC collimation system

    Energy Technology Data Exchange (ETDEWEB)

    Robert-Demolaize, G.; Drees, A.

    2012-01-19

    The RHIC collimation system is used to reduce background levels in both STAR and PHENIX detectors. With a push for higher luminosity in the near future, it becomes critical to check if and how the level of performance of the collimators can be improved. The following reviews a proposal for additional collimators placed further downstream of the current system and designed to intercept the tertiary halo coming out of the IR8 insertion before it can reach the triplet quadrupoles in either STAR or PHENIX. Simulations have been peformed to quantify the efficiency of additional collimator jaws in RHIC. Each figure presented in this article clearly shows that the additional mask collimators provide the expected reduction in losses around the machine, and especially to the incoming triplet to the STAR experiment (IP6), for the Yellow beam as much as for the Blue beam. Looking at compiled statistics for all three working point cases studied, proton losses around the machine are reduced by roughly one order of magnitude: at most a factor 30 for magnet losses, and at most a factor 40 for losses in spaces between magnets.

  16. Collimating Slicer for Optical Integral Field Spectroscopy

    CERN Document Server

    Laurent, Florence

    2016-01-01

    Integral Field Spectroscopy (IFS) is a technique that gives simultaneously the spectrum of each spatial sampling element in a given object field. It is a powerful tool which rearranges the data cube (x, y, lambda) represented by two spatial dimensions defining the field and the spectral decomposition in a detector plane. In IFS, the spatial unit reorganizes the field and the spectral unit is being composed of a classical spectrograph.The development of a Collimating Slicer aims at proposing a new type of integral field spectrograph which should be more compact. The main idea is to combine the image slicer with the collimator of the spectrograph, thus mixing the spatial and spectral units. The traditional combination of slicer, pupil and slit elements and the spectrograph collimator is replaced by a new one composed of a slicer and collimator only. In this paper, the state of the art of integral field spectroscopy using image slicers is described. The new system based onto the development of a Collimating Slic...

  17. Controlling the self-collimation characteristics of a near-infrared two-dimensional metallic photonic crystal

    Institute of Scientific and Technical Information of China (English)

    Feng Shuai; Ren Cheng; Wang Wen-Zhong; Wang Yi-Quan

    2012-01-01

    Self-collimation characteristics of the two-dimensional square-lattice photonic crystal (PC) consisting of metal rods immersed in silicon are studied by the finite-difference time-domain method.The Drude dispersion model is adopted to describe the metal rod,and the self-collimation behaviours of the near-infrared light through the PC are studied.The frequency region and the tolerance of incident angle for the self-collimation behaviour can be controlled by changing the shape of the metal rods.

  18. Multibeam collimator uses prism stack

    Science.gov (United States)

    Minott, P. O.

    1981-01-01

    Optical instrument creates many divergent light beams for surveying and machine element alignment applications. Angles and refractive indices of stack of prisms are selected to divert incoming laser beam by small increments, different for each prism. Angles of emerging beams thus differ by small, precisely-controlled amounts. Instrument is nearly immune to vibration, changes in gravitational force, temperature variations, and mechanical distortion.

  19. A Correlation Between the Intrinsic Brightness and Average Decay Rate of Gamma-ray Burst X-ray Afterglow Light Curves

    CERN Document Server

    Racusin, J L; de Pasquale, M; Kocevski, D

    2016-01-01

    We present a correlation between the average temporal decay ({\\alpha}X,avg,>200s) and early-time luminosity (LX,200s) of X-ray afterglows of gamma-ray bursts as observed by Swift-XRT. Both quantities are measured relative to a rest frame time of 200 s after the {\\gamma}-ray trigger. The luminosity average decay correlation does not depend on specific temporal behavior and contains one scale independent quantity minimizing the role of selection effects. This is a complementary correlation to that discovered by Oates et al. (2012) in the optical light curves observed by Swift-UVOT. The correlation indicates that on average, more luminous X-ray afterglows decay faster than less luminous ones, indicating some relative mechanism for energy dissipation. The X-ray and optical correlations are entirely consistent once corrections are applied and contamination is removed. We explore the possible biases introduced by different light curve morphologies and observational selection effects, and how either geometrical effe...

  20. Laser beam collimation using Talbot interferometry

    Science.gov (United States)

    Ganesan, A. R.; Venkateswarlu, Putcha

    1993-01-01

    A modified method of checking laser beam collimation using a single grating and a right-angled prism is presented. The self-images (Talbot images) of a grating illuminated by a collimated beam are formed at some distance from the grating. The use of a right-angled prism makes it possible to carry out the folding of the self-image with respect to the original grating and to ensure that the grating lines in the self-image and the actual grating are inclined at equal angles with respect to horizontal direction. It is concluded that the proposed collimation test method has an in-built reference and does not require precise orientation of the grating as in the two-grating method. Large beams can be tested with a small-size assembly.

  1. THE TWO STAGE CRYSTAL COLLIMATOR FOR RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    FLILLER, R.P. III; DREES, A.; GASSNER, D.; HAMMONS, L.; MCINTYRE, G.; TRBOJEVIC, D.; BIRYUKOV, V.; CHESNOKOV, Y.; TEREKHOV, V.

    2001-06-18

    The use of a two stage crystal collimation system in the RHIC yellow ring is examined. The system includes a copper beam scraper and a bent silicon crystal. While scrapers were installed in both of the RHIC rings before the year 2000 run, the crystal is installed for the 2001 run in one ring only, forming a two stage collimation system there. We present simulations of the expected channeling through the bent silicon crystal for both protons and gold ions with various beam parameters. This gives a picture of the particle losses around the ring, and the expected channeling efficiency. These results are then used to optimize the beam parameters in the area of the crystal to obtain maximum channeling efficiency, minimize out-scattering in the secondary collimator, and reduce beam halo.

  2. Macrostrain measurement using radial collimators at LANSCE

    Energy Technology Data Exchange (ETDEWEB)

    Bourke, M.A.M.; Roberts, J.A.; Davis, D.

    1996-06-01

    A series of `short` radial collimators have been implemented in the 90{degrees} scattering geometries on the neutron powder diffractometer at Los Alamos. The capability to perform macrostrain measurements has been improved by the commensurate ability to rapidly select a sampling volume appropriate to the specimen. The compact design of the collimators was dictated by the need to fit them in a cylindrical vacuum chamber as well as providing space in which to manipulate a specimen in three dimensions. Collimators of different vane lengths were fabricated to give 4 different resolutions for which 2/3 of the diffracted intensity comes form distances of 0.75, 1. 25, 2.5, and 4.0 mm along the incident beam. Qualifying scans and a demonstration of a cracked ring, containing a steep stress gradient, are included.

  3. Radiation collimator and systems incorporating same

    Energy Technology Data Exchange (ETDEWEB)

    Norman, Daren R. (Idaho Falls, ID); Yoon, Woo Y. (Idaho Falls, ID); Jones, James L. (Idaho Falls, ID); Haskell, Kevin J. (Idaho Falls, ID); Bennett, Brion D. (Idaho Falls, ID); Tschaggeny, Charles W. (Woods Cross, UT); Jones, Warren F. (Idaho Falls, ID)

    2011-09-13

    A collimator including a housing having disposed therein a shield element surrounding a converter core in which a photon beam is generated from electrons emanating from a linear accelerator. A beam channeler longitudinally adjacent the shield element has a beam aperture therethrough coaxially aligned with, and of the same diameter as, an exit bore of the converter core. A larger entry bore in the converter core is coaxial with, and longitudinally separated from, the exit bore thereof. Systems incorporating the collimator are also disclosed.

  4. Collimated Magnetron Sputter Deposition for Mirror Coatings

    DEFF Research Database (Denmark)

    Vickery, A.; Cooper-Jensen, Carsten P.; Christensen, Finn Erland;

    2008-01-01

    At the Danish National Space Center (DNSC), a planar magnetron sputtering chamber has been established as a research and production coating facility for curved X-ray mirrors for hard X-ray optics for astronomical X-ray telescopes. In the following, we present experimental evidence...... that a collimation of the sputtered particles is an efficient way to suppress the interfacial roughness of the produced multilayer. We present two different types of collimation optimized for the production of low roughness curved mirrors and flat mirrors, respectively....

  5. The New Transfer Line Collimation System for the LHC High Luminosity Era

    Energy Technology Data Exchange (ETDEWEB)

    Kain, Verena [CERN; Bracco, Chiara [CERN; Goddard, Brennan [CERN; Maciariello, Fausto [CERN; Meddahi, Malika [CERN; Mereghetti, Alessio [CERN; Steele, Genevieve [CERN; Velotti, Francesco [CERN; Gianfelice-Wendt, Eliana [Fermilab

    2014-07-01

    A set of passive absorbers is located at the end of each of the 3 km long injection lines to protect the LHC in case of failures during the extraction process from the LHC’s last pre-injector or the beam transfer itself. In case of an erroneous extraction, the absorbers have to attenuate the beam to a safe level and be robust enough themselves to survive the impact. These requirements are difficult to fulfil with the very bright and intense beams produced by the LHC injectors for the high luminosity era. This paper revisits the requirements for the SPS-to-LHC transfer line collimation system and the adapted strategy to fulfill these for the LHC high luminosity operation. A possible solution for the new transfer line collimation system is presented.

  6. Efficient bright white organic light-emitting diode based on non-doped ultrathin 5,6,11,12-tetraphenylnaphthacene layer

    Energy Technology Data Exchange (ETDEWEB)

    Li Lu [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China); Yu Junsheng [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)], E-mail: jsyu@uestc.edu.cn; Tang Xiaoqing; Wang Tao; Li Wei; Jiang Yadong [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2008-11-15

    High-performance undoped white organic light-emitting diode (OLED) has been fabricated using an ultrathin yellow-emitting layer of 5,6,11,12-tetraphenylnaphthacene (rubrene) inserted at two sides of interface between two N,N'-bis-(1-naphthyl)-N,N'- biphenyl-1,1'-biphenyl-4,4'- diamine (NPB) layers as a hole transporting and blue emissive layer, respectively. The results showed that a maximum luminance of the device reached to as high as 21,500 cd/m{sup 2} at 15 V. The power efficiencies of 2.5 and 1.6 lm/W at a luminance of 1000 and 10000 cd/m{sup 2}, respectively, were obtained. The peaks of electroluminescent (EL) spectra locate at 429 and 560 nm corresponding to the Commissions Internationale De L'Eclairage (CIE) coordinates of (0.32, 0.33), which is independent of bias voltage. The performance enhancement of the device may result from direct charge carrier trapping in rubrene. Energy transfer mechanism was also found in the EL process.

  7. A Bright Fluorescent Probe for H2S Enables Analyte-Responsive, 3D Imaging in Live Zebrafish Using Light Sheet Fluorescence Microscopy.

    Science.gov (United States)

    Hammers, Matthew D; Taormina, Michael J; Cerda, Matthew M; Montoya, Leticia A; Seidenkranz, Daniel T; Parthasarathy, Raghuveer; Pluth, Michael D

    2015-08-19

    Hydrogen sulfide (H2S) is a critical gaseous signaling molecule emerging at the center of a rich field of chemical and biological research. As our understanding of the complexity of physiological H2S in signaling pathways evolves, advanced chemical and technological investigative tools are required to make sense of this interconnectivity. Toward this goal, we have developed an azide-functionalized O-methylrhodol fluorophore, MeRho-Az, which exhibits a rapid >1000-fold fluorescence response when treated with H2S, is selective for H2S over other biological analytes, and has a detection limit of 86 nM. Additionally, the MeRho-Az scaffold is less susceptible to photoactivation than other commonly used azide-based systems, increasing its potential application in imaging experiments. To demonstrate the efficacy of this probe for H2S detection, we demonstrate the ability of MeRho-Az to detect differences in H2S levels in C6 cells and those treated with AOAA, a common inhibitor of enzymatic H2S synthesis. Expanding the use of MeRho-Az to complex and heterogeneous biological settings, we used MeRho-Az in combination with light sheet fluorescence microscopy (LSFM) to visualize H2S in the intestinal tract of live zebrafish. This application provides the first demonstration of analyte-responsive 3D imaging with LSFM, highlighting the utility of combining new probes and live imaging methods for investigating chemical signaling in complex multicellular systems. PMID:26061541

  8. Highly collimated source of cold Rubidium atoms from a two dimensional magneto-optical trap

    CERN Document Server

    Carrat, Vincent; Jacquey, Marion; Tabosa, José W; de Lesegno, Bruno Viaris; Pruvost, Laurence

    2013-01-01

    Using a blue detuned laser shaped in a Laguerre-Gaussian donut mode we highly collimate the output of a two dimensional magneto-optical trap. The resulting atomic beam has a 1 mm diameter, its divergence is reduced from 40 down to 3 mrad and the atomic density is increased by a factor of 200. The collimation effect has been studied versus the order of the Laguerre-Gaussian mode (up to 10) and the laser atom frequency detuning (2 to 120 GHz). The 2D-colli-MOT study allows us to determine the best conditions which minimize the atom heating due to residual light absorption and optimize the collimation effect. The 2D-colli MOT could provide a new tool to fill a 3D-MOT using lasers with millimeter range diameters and thus sparing the laser power.

  9. EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014. Scientific Opinion on the substantiation of a health claim related to a combination of lutein and zeaxanthin and improved vision under bright light conditions pursuant to Article 13(5) of Regulation (EC) No 1924/2006

    DEFF Research Database (Denmark)

    Tetens, Inge

    EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014. Scientific Opinion on the substantiation of a health claim related to a combination of lutein and zeaxanthin and improved vision under bright light conditions pursuant to Article 13(5) of Regulation (EC) No 1924/2006....

  10. A dosimetric comparison of various multileaf collimators

    International Nuclear Information System (INIS)

    The dosimetric characteristics of three multileaf collimator (MLC) systems (Elekta, Siemens and Varian) having 10 mm leaf width are compared. A 6 MV photon beam was used from each unit for measurements. Film dosimetry was performed for the measurements and the analysis techniques were exactly duplicated in each system. Two of the collimators have rounded leaf ends (Elekta and Varian) and the third (Siemens) has a flat end that follows beam divergence. A scanning densitometer (Wellhoefer with 0.45 mm spot and 0.5 mm step size) was used for film analysis. The dosimetric characteristics studied include: penumbra width (80-20%) as a function of position of the leaf end in the field, inter- and intra-leaf radiation leakage, dose distribution of the tongue and groove, and isodose curves for stepped leaves forming 45 deg. angle beam edge. Results show that MLC designs with divergent and non-divergent leaves produce penumbra (80-20%) widths that are within 2.0 mm of each other. However, the distance of the collimator from the x-ray target plays an important role, and the smallest penumbra width was noted for the Varian MLC despite its rounded leaf-end design. Compared to the other systems, this collimator is positioned about 15 cm closer to the patient which affects the skin dose. The MLC with flat leaf end, although closer to the target, showed slightly poorer penumbra width. Inter-leaf leakage through the leaves is 1.3% for two of the collimators (Elekta and Varian) with the backup jaws and is nearly 1% for the third system (Siemens). The Siemens MLC produces reduced tongue-and-groove effect compared to the other two collimators (Elekta and Varian). The isodose undulation for a stepped edge is found to be significant for the collimator closest to the patient (Varian) and does not depend on the leaf-end shape. There is no perfect MLC system that can be recommended, rather each one has unique advantages and disadvantages that should be weighed with comfort, ease and cost

  11. Robust Collimation Control of Laser-Generated Ion Beam

    CERN Document Server

    Kawata, S; Kamiyama, D; Nagashima, T; Barada, D; Gu, Y J; Li, X; Yu, Q; Kong, Q; Wang, P X

    2015-01-01

    The robustness of a structured collimation device is discussed for an intense-laser-produced ion beam. In this paper the ion beam collimation is realized by the solid structured collimation device, which produces the transverse electric field; the electric field contributes to reduce the ion beam transverse velocity and collimate the ion beam. Our 2.5 dimensional particle-in cell simulations demonstrate that the collimation device is rather robust against the changes in the laser parameters and the collimation target sizes. The intense short-pulse lasers are now available, and are used to generate an ion beam. The issues in the laser ion acceleration include an ion beam collimation, ion energy spectrum control, ion production efficiency, ion energy control, ion beam bunching, etc. The laser-produced ion beam tends to expand in the transverse and longitudinal directions during the ion beam propagation. The ion beam collimation is focused in this paper.

  12. ENERGY DEPOSITION STUDIES FOR POSSIBLE INNOVATIVE PHASE II COLLIMATOR DESIGNS

    CERN Document Server

    Lari, L; Brugger, M; Cerutti, F; Ferrari, A; Vlachoudis, V; Weiler, T

    2009-01-01

    Due to the known limitations of Phase I LHC collimators in stable physics conditions, the LHC collimation system will be complemented by additional 30 Phase II collimators. The Phase II collimation system is designed to improve cleaning efficiency and to minimize the collimator-induced impedance with the main function of protecting the Super Conducting (SC) magnets from quenching due to beam particle losses. To fulfil these requirements, different possible innovative collimation designs were taken in consideration. Advanced jaw materials, including new composite materials (e.g. Cu–Diamond), jaw SiC insertions, coating foil, in-jaw instrumentation (e.g. BPM) and improved mechanical robustness of the jaw are the main features of these new promising Phase II collimator designs developed at CERN. The FLUKA Monte Carlo code is extensively used to evaluate the behavior of these collimators in the most radioactive areas of LHC, supporting the mechanical integration. These studies aim to identify the possible criti...

  13. Energy Deposition Studies for Possible Innovative Phase II Collimator Designs

    CERN Document Server

    Lari, L; Brugger, M; Cerutti, F; Ferrari, A; Vlachoudis, V; Weiler, T

    2010-01-01

    Due to the known limitations of Phase I LHC collimators in stable physics conditions, the LHC collimation system will be complemented by additional 30 Phase II collimators. The Phase II collimation system is designed to improve cleaning efficiency and to minimize the collimator-induced impedance with the main function of protecting the Super Conducting (SC) magnets from quenching due to beam particle losses. To fulfil these requirements, different possible innovative collimation designs were taken in consideration. Advanced jaw materials, including new composite materials (e.g. Cu–Diamond), jaw SiC insertions, coating foil, in-jaw instrumentation (e.g. BPM) and improved mechanical robustness of the jaw are the main features of these new promising Phase II collimator designs developed at CERN. The FLUKA Monte Carlo code is extensively used to evaluate the behavior of these collimators in the most radioactive areas of LHC, supporting the mechanical integration. These studies aim to identify the possible criti...

  14. Online Status and Settings Monitoring for the LHC Collimators

    CERN Document Server

    Valentino, G; Jacquet, D; Redaelli, S; Veyrunes, E

    2014-01-01

    The Large Hadron Collider is equipped with 100 movable collimators. The LHC collimator control system is responsible for the accurate synchronization of around 400 axes of motion at the microsecond level, and with the precision of a few micrometers.

  15. Comparison of effects of bright light therapy alone or combined with fluoxetine on severity of depression, circadian rhythms, mood disturbance, and sleep quality, in patients with non-seasonal depression

    Directory of Open Access Journals (Sweden)

    Ağargün MY

    2013-06-01

    Full Text Available Mehmet Yücel Agargün,1 Gokben Hizli Sayar,2 Hüseyin Bulut,3 Oguz Tan21Medipol University, Department of Psychiatry, Istanbul, Turkey; 2Uskudar University, Neuropsychiatry Istanbul Hospital, Istanbul, Turkey; 3Büyükçekmece Government Hospital, Department of Psychiatry, Istanbul, TurkeyPurpose: To compare effects of bright light therapy (BLT alone or combined with the selective serotonin reuptake inhibitor (SSRI fluoxetine, on severity of depression, circadian rhythms, mood disturbance, and sleep quality, in patients with non-seasonal depression.Patients and methods: Drug-free patients who were administered 10,000 lux of BLT for 30 minutes for 7 days comprised the BLT group (n = 7, while patients who started fluoxetine as an add-on treatment day comprised the SSRI + BLT group (n = 8. The primary outcomes were severity of depression, measured using the Hamilton Depression Rating Scale (HAM-D and the Beck Depression Inventory (BDI; chronotype, measured using the Morningness Eveningness Questionnaire (MEQ; mood disturbance, measured using the Profile of Mood States (POMS survey; and sleep quality, measured using the Pittsburgh Sleep Quality Index (PSQI, before and after treatment in both groups.Results: All patients completed the study, and none reported obvious side effects. The mean onset age of depression was 26.1 years ± 5.3 years in the BLT group and 27 years ± 9.5 years in the SSRI + BLT group (P = 0.425. The number of past depressive episodes was 1.29 ± 0.76 in the BLT group, and 1.5 ± 0.8 in the SSRI + BLT group (P = 0.427. The difference between pre- and posttreatment scores revealed no significant difference between groups for the HAM-D scale, BDI, MEQ, POMS survey, and the PSQI.Conclusion: This study suggests that BLT is effective with respect to the severity of depression, circadian rhythms, mood disturbance, and sleep quality, in non-seasonal depression. However, there was no evidence in favor of adjunctive fluoxetine with BLT

  16. BPM Design and Impedance Considerations for a Rotatable Collimator for the LHC Collimation Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jeffrey Claiborne; /SLAC; Keller, Lewis; /SLAC; Lundgren, Steven; /SLAC; Markiewicz, Thomas; /SLAC; Young, Andrew; /SLAC

    2010-08-26

    The Phase II upgrade to the LHC collimation system calls for complementing the 30 high robust Phase I graphite secondary collimators with 30 high Z Phase II collimators. This paper reports on BPM and impedance considerations and measurements of the integrated BPMs in the prototype rotatable collimator to be installed in the Super Proton Synchrotron (SPS) at CERN. The BPMs are necessary to align the jaws with the beam. Without careful design the beam impedance can result in unacceptable heating of the chamber wall or beam instabilities. The impedance measurements involve utilizing both a single displaced wire and two wires excited in opposite phase to disentangle the driving and detuning transverse impedances. Trapped mode resonances and longitudinal impedance are to also be measured and compared with simulations. These measurements, when completed, will demonstrate the device is fully operational and has the impedance characteristics and BPM performance acceptable for installation in the SPS.

  17. Design of high-brightness TEM00-mode solar-pumped laser for renewable material processing

    Science.gov (United States)

    Liang, D.; Almeida, J.

    2014-08-01

    The conversion of sunlight into laser light by direct solar pumping is of ever-increasing importance because broadband, temporally constant, sunlight is converted into laser light, which can be a source of narrowband, collimated, rapidly pulsed, radiation with the possibility of obtaining extremely high brightness and intensity. Nonlinear processes, such as harmonic generation, might be used to obtain broad wavelength coverage, including the ultraviolet wavelengths, where the solar flux is very weak. The direct excitation of large lasers by sunlight offers the prospect of a drastic reduction in the cost of coherent optical radiation for high average power materials processing. This renewable laser has a large potential for many applications such as high-temperature materials processing, renewable magnesium-hydrogen energy cycle and so on. We propose here a scalable TEM00 mode solar laser pumping scheme, which is composed of four firststage 1.13 m diameter Fresnel lenses with its respective folding mirrors mounted on a two-axis automatic solar tracker. Concentrated solar power at the four focal spots of these Fresnel lenses are focused individually along a common 3.5 mm diameter, 70 mm length Nd:YAG rod via four pairs of second-stage fused-silica spherical lenses and third-stage 2D-CPCs (Compound Parabolic Concentrator), sitting just above the laser rod which is also double-pass pumped by four V-shaped pumping cavities. Distilled water cools both the rod and the concentrators. 15.4 W TEM00 solar laser power is numerically calculated, corresponding to 6.7 times enhancement in laser beam brightness.

  18. Study on the Backward Scattering Power of a Collimated Green-Blue Laser Beam Transmitting in the Seawater

    Institute of Scientific and Technical Information of China (English)

    陈磊; 罗莉; 戴德昌; 罗琦; 丘志仁; 周建英

    2001-01-01

    Based on the theory of light beam transmitting in the seawater and the principle of scattering between light and particles, we have studied the relation between water quality parameter and backward scattering power of collimated green-blue laser beam, which can be used to interpret the existed airborne laser experimental data successfully.

  19. The Bright New Financial System

    Directory of Open Access Journals (Sweden)

    Associate Professor Adela Coman

    2009-05-01

    Full Text Available By the end of 2008, Mr. Paul Volcker gave financiers a devastating critique. “For all its talented participants, for all its rich rewards” he said, the “bright new financial system” has “failed the test of the marketplace”.In light of the events of recent weeks, it is hard to disagree. A financial system that ends up with the government taking over some of its biggest institutions in serial weekend rescues and which requires the promise of 700 billion dollars in public money to stave off catastrophe is not a trustworthy system. The disappearance of all five big American investment banks – either by bankruptcy or rebirth as commercial banks – is powerful evidence that Wall Street failed “the test of the marketplace”. Something went wrong.But what exactly and why? A more serious analysis needs to distinguish between three separate questions: what is Mr. Volcker’s “bright new financial system”? Second, how far was today’s mess created by instabilities that are inseparable from modern finance and how far was it fuelled by other errors and distortions? Third, to the extent that modern finance does bear the blame, what is the balance between its costs and its benefits and how can it be improved?

  20. Collimator settings and performance in 2011 and 2012

    International Nuclear Information System (INIS)

    Collimator settings and performance are key parameters for deciding the reach in intensity and β* in order to conclude on possible limits for the 2012 run, a summary is first given of the relevant running experience in 2011 and the collimation-related MDs. These include among others tight collimator settings, a quench test, and aperture measurements. Based on the 2011 experience, we conclude on possible running scenarios for 2012 in terms of collimator settings, intensity and β* from the collimation point of view. (authors)

  1. The Linac Cooherent Light Source (LCLS) Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Juhao; Emma, P.; /SLAC

    2007-03-21

    The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) based on the final kilometer of the Stanford Linear Accelerator. Such an FEL requires a high energy, high brightness electron beam to drive the FEL instability to saturation. When fed by an RF-photocathode gun, and modified to include two bunch compressor chicanes, the SLAC linac will provide such a high quality beam at 14 GeV and 1-{micro}m normalized emittance. In this paper, we report on recent linac studies, including beam stability and tolerances, longitudinal and transverse feedback systems, conventional and time-resolved diagnostics, and beam collimation systems. Construction and installation of the injector through first bunch compressor will be completed by December 2006, and electron commissioning is scheduled to begin in January of 2007.

  2. Can Collimated Extraterrestrial Signals be Intercepted?

    CERN Document Server

    Forgan, Duncan H

    2014-01-01

    The Optical Search for Extraterrestrial Intelligence (OSETI) attempts to detect collimated, narrowband pulses of electromagnetic radiation. These pulses may either consist of signals intentionally directed at the Earth, or signals between two star systems with a vector that unintentionally intersects the Solar System, allowing Earth to intercept the communication. But should we expect to be able to intercept these unintentional signals? And what constraints can we place upon the frequency of intelligent civilisations if we do? We carry out Monte Carlo Realisation simulations of interstellar communications between civilisations in the Galactic Habitable Zone (GHZ) using collimated beams. We measure the frequency with which beams between two stars are intercepted by a third. The interception rate increases linearly with the fraction of communicating civilisations, and as the cube of the beam opening angle, which is somewhat stronger than theoretical expectations, which we argue is due to the geometry of the GHZ...

  3. Can Collimated Extraterrestrial Signals be Intercepted?

    OpenAIRE

    Forgan, Duncan H.

    2014-01-01

    The Optical Search for Extraterrestrial Intelligence (OSETI) attempts to detect collimated, narrowband pulses of electromagnetic radiation. These pulses may either consist of signals intentionally directed at the Earth, or signals between two star systems with a vector that unintentionally intersects the Solar System, allowing Earth to intercept the communication. But should we expect to be able to intercept these unintentional signals? And what constraints can we place upon the frequency of ...

  4. Turbulent Magnetohydrodynamic Jet Collimation and Thermal Driving

    OpenAIRE

    Williams, Peter T.

    2003-01-01

    We have argued that magnetohydrodynamic (MHD) turbulence in an accretion disk naturally produces hoop-stresses, and that in a geometrically-thick flow these stresses could both drive and collimate an outflow. We based this argument on an analogy of turbulent MHD fluids to viscoelastic fluids, in which azimuthal shear flow creates hoop-stresses that cause a variety of flow phenomena, including the Weissenberg effect in which a fluid climbs a spinning rod. One of the more important differences ...

  5. Evaluation of infrared collimators for testing thermal imaging systems

    Science.gov (United States)

    Chrzanowski, K.

    2007-06-01

    Infrared reflective collimators are important components of expensive sophisticated test systems used for testing thermal imagers. Too low quality collimators can become a source of significant measurement errors and collimators of too high quality can unnecessarily increase cost of a test system. In such a situation it is important for test system users to know proper requirements on the collimator and to be able to verify its performance. A method for evaluation of infrared reflective collimators used in test systems for testing thermal imagers is presented in this paper. The method requires only easily available optical equipment and can be used not only by collimator manufactures but also by users of test equipment to verify performance of the collimators used for testing thermal imagers.

  6. Subwavelength nanobrush target to collimate fast electrons

    Science.gov (United States)

    Zhao, Zongqing; Cao, Lihua; Cao, Leifeng; Zhou, Weimin; Wu, Yuchi; Zhu, Bin; Dong, Kegong; Zhang, Baohan; Ding, Yongkun; Gu, Yuqiu

    2011-10-01

    A subwavelength nanobrush target was proposed to collimate fast electrons in laser plasma interaction, which consists of a 5 μm copper underlay covered with a 20 μm thick layer of metallic fibers. The diameter of the individual fibers is about 200 nm and the spacing between them is about 150 nm. The experiment was hold at SILEX-I laser facility (10 J, 31 fs, 300 TW). When a subwavelength nanobrush target interacts with ultraintense laser of 7.9*1018/cm2, highly collimated fast electron beam with divergence angle nearly zero whereas the divergence of the plane target is 40 degree. Two-dimensional particle-in-cell (PIC) simulations show that the fast electrons will be accelerated and guided by strong transient electromagnetic fields created at the wall surfaces of nanobrushs. Both experiment and simulation show that the subwavelength nanobrush target can indeed generate fast electrons more efficiency and collimate them. The scheme should be useful for fast ignition and K α source research in inertial confinement fusion.

  7. Bright Lights and Questions: Using Mutual Interrogation

    Science.gov (United States)

    Adam, Aishikin; Alangui, Willy; Barton, Bill

    2010-01-01

    Mutual Interrogation is a research methodology for ethnomathematics proposed by Alangui in 2006 in an attempt to avoid the potential inequality set up when a restricted cultural practice is viewed through the lens of the near-universal and highly developed research domain of mathematics. Using three significant examples of mutual interrogation in…

  8. CA BrightStor

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    CA推出的BrightStor系列存储管理解决方案已经成为企业电子商务体系架构管理战略中举足轻重的组成部分。BrightStor是一整套企业级的智能化存储管理解决方案,定位在存储硬件设备和上层应用之间,通过各种集成化的产品和工具为驻留在企业任何位置的数据提供全方位的、有效的存储管理和保护。

  9. Bright Economic Prospects

    Institute of Scientific and Technical Information of China (English)

    Zhang Minqiu

    2004-01-01

    @@ India is expected to register an 8.2% growth rate for the 2003-04 fiscal year. The overall economic situation this year has been satisfactory despite the scaled down 6-6.5% growth rate for the new fiscal year due to oil price hikes, reduced monsoon volume and some 7% inflation. Judging from the following factors, bright prospects are in store for the country down the road.

  10. Improvement in Brightness Uniformity by Compensating for the Threshold Voltages of Both the Driving Thin-Film Transistor and the Organic Light-Emitting Diode for Active-Matrix Organic Light-Emitting Diode Displays

    OpenAIRE

    Ching-Lin Fan; Hao-Wei Chen; Hui-Lung Lai; Bo-Liang Guo; Bohr-Ran Huang

    2014-01-01

    This paper proposes a novel pixel circuit design and driving method for active-matrix organic light-emitting diode (AM-OLED) displays that use low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) as driving element. The automatic integrated circuit modeling simulation program with integrated circuit emphasis (AIM-SPICE) simulator was used to verify that the proposed pixel circuit, which comprises five transistors and one capacitor, can supply uniform output current. The v...

  11. Comparison of LHC collimation setups with manual and semi-automatic collimator alignment

    CERN Document Server

    Valentino, G; Bruce, R; Burkart, F; Cauchi, M; Deboy, D; Redaelli, S; Rossi, A; Sammut, N; Wollmann, D

    2011-01-01

    The LHC collimation system beam-based alignment procedure has recently been upgraded to a semi-automatic process in order to increase its efficiency. In this paper, we describe the parameters used to measure the accuracy, stability and performance of the beam-based alignment of the LHC collimation system. This is followed by a comparison of the results at 450 GeV and 3.5 TeV with (1) a manual alignment and (2) with the results for semi-automatic alignment.

  12. Low surface brightness galaxies

    Science.gov (United States)

    Vanderhulst, J. M.; Deblok, W. J. G.; Mcgaugh, S. S.; Bothun, G. D.

    1993-01-01

    A program to investigate the properties of low surface brightness (LSB) galaxies involving surface photometry in U, B, V, R, I, and H-alpha, HI imaging with the Westerbork Synthesis Radio Telescope (WSRT) and the very large array (VLA) and spectrophotometry of H2 regions in LSB galaxies is underway. The goal is to verify the idea that LSB galaxies have low star formation rates because the local gas density falls below the critical density for star formation, and to study the stellar population and abundances in LSB galaxies. Such information should help understanding the evolutionary history of LSB galaxies. Some preliminary results are reported.

  13. Improvement in Brightness Uniformity by Compensating for the Threshold Voltages of Both the Driving Thin-Film Transistor and the Organic Light-Emitting Diode for Active-Matrix Organic Light-Emitting Diode Displays

    Science.gov (United States)

    Fan, Ching-Lin; Lai, Hui-Lung; Chang, Jyu-Yu

    2010-05-01

    In this paper, we propose a novel pixel design and driving method for active-matrix organic light-emitting diode (AM-OLED) displays using low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs). The proposed threshold voltage compensation circuit, which comprised five transistors and two capacitors, has been verified to supply uniform output current by simulation work using the automatic integrated circuit modeling simulation program with integrated circuit emphasis (AIM-SPICE) simulator. The driving scheme of this voltage programming method includes four periods: precharging, compensation, data input, and emission. The simulated results demonstrate excellent properties such as low error rate of OLED anode voltage variation (<1%) and high output current. The proposed pixel circuit shows high immunity to the threshold voltage deviation characteristics of both the driving poly-Si TFT and the OLED.

  14. Preliminary assessment of beam impact consequences on LHC Collimators

    CERN Document Server

    Cauchi, M; Bertarelli, A; Bruce, R; Carra, F; Dallocchio, A; Deboy, D; Mariani, N; Rossi, A; Lari, L; Mollicone, P; Sammut, N

    2011-01-01

    The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, the robustness of the collimators plays an important role. An accident, which causes the proton beam to hit a collimator, might result in severe beam-induced damage and, in some cases, replacement of the collimator, with consequent downtime for the machine. In this paper, several case studies representing different realistic beam impact scenarios are shown. A preliminary analysis of the thermal response of tertiary collimators to beam impact is presented, from which the most critical cases can be identified. Such work will also help to give an initial insight on the operational constraints of the LHC by taking into account all relevant collimator damage limits.

  15. New scheme of high-precision visual collimator

    Science.gov (United States)

    Ge, Zhaoxiang; Ying, Han; Chen, Lei

    1998-08-01

    Machine manufacture and installation, special constructional engineering and precision engineering surveying need a very high precision collimator. In the text, we discus a plane focusing visual collimator, which had been specially made for the synchrotron accelerator. Using an electronic spirit level as the reference element, CCD automatic aiming system, photoelectric readout device and computer processing technology, the new visual collimator has a much higher precision and can be used more quickly, more conveniently and more reliably.

  16. Improvement in Brightness Uniformity by Compensating for the Threshold Voltages of Both the Driving Thin-Film Transistor and the Organic Light-Emitting Diode for Active-Matrix Organic Light-Emitting Diode Displays

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2014-01-01

    Full Text Available This paper proposes a novel pixel circuit design and driving method for active-matrix organic light-emitting diode (AM-OLED displays that use low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs as driving element. The automatic integrated circuit modeling simulation program with integrated circuit emphasis (AIM-SPICE simulator was used to verify that the proposed pixel circuit, which comprises five transistors and one capacitor, can supply uniform output current. The voltage programming method of the proposed pixel circuit comprises three periods: reset, compensation with data input, and emission periods. The simulated results reflected excellent performance. For instance, when ΔVTH=±0.33 V, the average error rate of the OLED current variation was low (<0.8%, and when ΔVTH_OLED=+0.33 V, the error rate of the OLED current variation was 4.7%. Moreover, when the I×R (current × resistance drop voltage of a power line was 0.3 V, the error rate of the OLED current variation was 5.8%. The simulated results indicated that the proposed pixel circuit exhibits high immunity to the threshold voltage deviation of both the driving poly-Si TFTs and OLEDs, and simultaneously compensates for the I×R drop voltage of a power line.

  17. Optimization of convergent collimators for pixelated SPECT systems

    Energy Technology Data Exchange (ETDEWEB)

    Capote, Ricardo M.; Matela, Nuno; Conceicao, Raquel C.; Almeida, Pedro [Universidade de Lisboa, Faculdade de Ciencias, Instituto de Biofisica e Engenharia Biomedica, Campo Grande, 1749-016 Lisboa (Portugal)

    2013-06-15

    Purpose: The optimization of the collimator design is essential to obtain the best possible sensitivity in single photon emission computed tomography imaging. The aim of this work is to present a methodology for maximizing the sensitivity of convergent collimators, specifically designed to match the pitch of pixelated detectors, for a fixed spatial resolution value and to present some initial results using this approach. Methods: Given the matched constraint, the optimal collimator design cannot be simply found by allowing the highest level of septal penetration and spatial resolution consistent with the imposed restrictions, as it is done for the optimization of conventional collimators. Therefore, an algorithm that interactively calculates the collimator dimensions, with the maximum sensitivity, which respect the imposed restrictions was developed and used to optimize cone and fan beam collimators with tapered square-shaped holes for low (60-300 keV) and high energy radiation (300-511 keV). The optimal collimator dimensions were locally calculated based on the premise that each hole and septa of the convergent collimator should locally resemble an appropriate optimal matched parallel collimator. Results: The optimal collimator dimensions, calculated for subcentimeter resolutions (3 and 7.5 mm), common pixel sizes (1.6, 2.1, and 2.5 mm), and acceptable septal penetration at 140 keV, were approximately constant throughout the collimator, despite their different hole incidence angles. By using these input parameters and a less strict septal penetration value of 5%, the optimal collimator dimensions and the corresponding mass per detector area were calculated for 511 keV. It is shown that a low value of focal distance leads to improvements in the average sensitivity at a fixed source-collimator distance and resolution. The optimal cone beam performance outperformed that of other optimal collimation geometries (fan and parallel beam) in imaging objects close to the

  18. Tests of a silicon wafer based neutron collimator

    Energy Technology Data Exchange (ETDEWEB)

    Cussen, L.D. E-mail: leo.cussen@vu.edu.au; Vale, C.J.; Anderson, I.S.; Hoeghoj, P

    2001-10-01

    A Soller slit neutron collimator has been prepared by stacking 160 {mu}m thick single crystal silicon wafers coated on one surface with 4 {mu}m of gadolinium metal. The collimator has an angular width of 20 min full width at half maximum and an effective length of 2.75 cm. The collimator has beam dimensions of 1 cm wide by 5.3 cm high. Tests at neutron wavelengths 7.5A and 1.8A showed a peak transmission of 88% within 2% of the optimum theoretical possibility. The background suppression in the wings is comparable with that of conventional neutron collimators.

  19. Tests of a silicon wafer based neutron collimator

    CERN Document Server

    Cussen, L D; Anderson, I S; Hoeghoj, P

    2001-01-01

    A Soller slit neutron collimator has been prepared by stacking 160 mu m thick single crystal silicon wafers coated on one surface with 4 mu m of gadolinium metal. The collimator has an angular width of 20 min full width at half maximum and an effective length of 2.75 cm. The collimator has beam dimensions of 1 cm wide by 5.3 cm high. Tests at neutron wavelengths 7.5A and 1.8A showed a peak transmission of 88% within 2% of the optimum theoretical possibility. The background suppression in the wings is comparable with that of conventional neutron collimators.

  20. Tests of a silicon wafer based neutron collimator

    International Nuclear Information System (INIS)

    A Soller slit neutron collimator has been prepared by stacking 160 μm thick single crystal silicon wafers coated on one surface with 4 μm of gadolinium metal. The collimator has an angular width of 20 min full width at half maximum and an effective length of 2.75 cm. The collimator has beam dimensions of 1 cm wide by 5.3 cm high. Tests at neutron wavelengths 7.5A and 1.8A showed a peak transmission of 88% within 2% of the optimum theoretical possibility. The background suppression in the wings is comparable with that of conventional neutron collimators

  1. Lightness functions

    DEFF Research Database (Denmark)

    Campi, Stefano; Gardner, Richard; Gronchi, Paolo;

    2012-01-01

    Variants of the brightness function of a convex body K in n-dimensional Euclidean are investigated. The Lambertian lightness function L(K; v , w ) gives the total reflected light resulting from illumination by a light source at infinity in the direction w that is visible when looking...... in the direction v . The partial brightness function R( K ; v , w ) gives the area of the projection orthogonal to v of the portion of the surface of K that is both illuminated by a light source from the direction w and visible when looking in the direction v . A class of functions called lightness functions...... is introduced that includes L(K;.) and R(K;.) as special cases. Much of the theory of the brightness function like uniqueness, stability, and the existence and properties of convex bodies of maximal and minimal volume with finitely many function values equal to those of a given convex body, is extended...

  2. Leaf sequencing algorithms for segmented multileaf collimation

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, Srijit [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Sahni, Sartaj [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Li, Jonathan [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Palta, Jatinder [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Ranka, Sanjay [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States)

    2003-02-07

    The delivery of intensity-modulated radiation therapy (IMRT) with a multileaf collimator (MLC) requires the conversion of a radiation fluence map into a leaf sequence file that controls the movement of the MLC during radiation delivery. It is imperative that the fluence map delivered using the leaf sequence file is as close as possible to the fluence map generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. Optimization of the leaf sequencing algorithm has been the subject of several recent investigations. In this work, we present a systematic study of the optimization of leaf sequencing algorithms for segmental multileaf collimator beam delivery and provide rigorous mathematical proofs of optimized leaf sequence settings in terms of monitor unit (MU) efficiency under most common leaf movement constraints that include minimum leaf separation constraint and leaf interdigitation constraint. Our analytical analysis shows that leaf sequencing based on unidirectional movement of the MLC leaves is as MU efficient as bidirectional movement of the MLC leaves.

  3. Leaky wave lenses for spoof plasmon collimation.

    Science.gov (United States)

    Panaretos, Anastasios H; Werner, Douglas H

    2016-06-27

    We theoretically demonstrate the feasibility of collimating radiating spoof plasmons using a leaky wave lens approach. Spoof plasmons are surface waves excited along reactance surfaces realized through metallic corrugations. By employing a periodic perturbation to the geometric profile of this type of reactance surface, it becomes feasible to convert the excited spoof plasmons into free-space radiating leaky wave modes. It is demonstrated that by structurally modifying such a corrugated surface through the introduction of a non-uniform sinusoidally modulated reactance profile, then a tapered wavenumber, with a real part less than that of free space, can be established along the surface. In this way the radiating properties of the structure (amplitude and phase) can be locally controlled thereby creating a radiating effect similar to that of a non-uniform current distribution. By properly engineering the space dependent wavenumber along the corrugated surface, different regions of the structure will emit spoof plasmon energy at different angles with varying intensity. The combined effect is the emission of an electromagnetic wave exhibiting a converging wave-front that eventually collimates spoof plasmon energy at some desired focal point.

  4. How Bright Can Supernovae Get?

    Science.gov (United States)

    Kohler, Susanna

    2016-04-01

    Supernovae enormous explosions associated with the end of a stars life come in a variety of types with different origins. A new study has examined how the brightest supernovae in the Universe are produced, and what limits might be set on their brightness.Ultra-Luminous ObservationsRecent observations have revealed many ultra-luminous supernovae, which haveenergies that challenge our abilities to explain them usingcurrent supernova models. An especially extreme example is the 2015 discovery of the supernova ASASSN-15lh, which shone with a peak luminosity of ~2*1045 erg/s, nearly a trillion times brighter than the Sun. ASASSN-15lh radiated a whopping ~2*1052 erg in the first four months after its detection.How could a supernova that bright be produced? To explore the answer to that question, Tuguldur Sukhbold and Stan Woosley at University of California, Santa Cruz, have examined the different sources that could produce supernovae and calculated upper limits on the potential luminosities ofeach of these supernova varieties.Explosive ModelsSukhbold and Woosley explore multiple different models for core-collapse supernova explosions, including:Prompt explosionA stars core collapses and immediately explodes.Pair instabilityElectron/positron pair production at a massive stars center leads to core collapse. For high masses, radioactivity can contribute to delayed energy output.Colliding shellsPreviously expelled shells of material around a star collide after the initial explosion, providing additional energy release.MagnetarThe collapsing star forms a magnetar a rapidly rotating neutron star with an incredibly strong magnetic field at its core, which then dumps energy into the supernova ejecta, further brightening the explosion.They then apply these models to different types of stars.Setting the LimitThe authors show that the light curve of ASASSN-15lh (plotted in orange) can be described by a model (black curve) in which a magnetar with an initial spin period of 0.7 ms

  5. Globe at Night - Sky Brightness Monitoring Network

    Science.gov (United States)

    Cheung, Sze Leung; Pun, Jason Chun Shing; SO, Chu-wing; Shibata, Yukiko; Walker, Constance Elaine; Agata, Hidehiko

    2015-08-01

    The Global at Night - Sky Brightness Monitoring Network (GaN-MN) is an international project for long-term monitoring of night sky conditions around the world. The GaN-MN consists of fixed monitoring stations each equipped with a Sky Quality Meter - Lensed Ethernet (SQM-LE), which is a specialized light sensor for night sky brightness (NSB) measurement. NSB data are continuously collected at high sampling frequency throughout the night, and these data will be instantly made available to the general public to provide a real-time snapshot of the global light pollution condition. A single data collection methodology, including data sampling frequency, data selection criteria, device design and calibration, and schemes for data quality control, was adopted to ensure uniformity in the data collected. This is essential for a systematic and global study of the level of light pollution. The data collected will also provide the scientific backbone in our efforts to contribute to dark sky conservation through education to the general public and policy makers. The GaN-MN project is endorsed by the IAU IYL Executive Committee Working Group as a major Cosmic Light program in the International Year of Light.

  6. Electron beam collimation with a 40 000 tip metallic double-gate field emitter array and in-situ control of nanotip sharpness distribution

    Energy Technology Data Exchange (ETDEWEB)

    Helfenstein, P.; Guzenko, V. A.; Tsujino, S. [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Fink, H.-W. [Physik Institut, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)

    2013-01-28

    The generation of highly collimated electron beams from a double-gate field emitter array with 40000 metallic tips and large collimation gate apertures is reported. Field emission beam measurements demonstrated the reduction of the beam envelope down to the array size by applying a negative potential to the on-chip gate electrode for the collimation of individual field emission beamlets. Owing to the optimized gate structure, the concomitant decrease of the emission current was minimal, leading to a net enhancement of the current density. Furthermore, a noble gas conditioning process was successfully applied to the double-gate device to improve the beam uniformity in-situ with orders of magnitude increase of the active emission area. The results show that the proposed double-gate field emission cathodes are promising for high current and high brightness electron beam applications such as free-electron lasers and THz power devices.

  7. Electron beam collimation with a 40 000 tip metallic double-gate field emitter array and in-situ control of nanotip sharpness distribution

    Science.gov (United States)

    Helfenstein, P.; Guzenko, V. A.; Fink, H.-W.; Tsujino, S.

    2013-01-01

    The generation of highly collimated electron beams from a double-gate field emitter array with 40000 metallic tips and large collimation gate apertures is reported. Field emission beam measurements demonstrated the reduction of the beam envelope down to the array size by applying a negative potential to the on-chip gate electrode for the collimation of individual field emission beamlets. Owing to the optimized gate structure, the concomitant decrease of the emission current was minimal, leading to a net enhancement of the current density. Furthermore, a noble gas conditioning process was successfully applied to the double-gate device to improve the beam uniformity in-situ with orders of magnitude increase of the active emission area. The results show that the proposed double-gate field emission cathodes are promising for high current and high brightness electron beam applications such as free-electron lasers and THz power devices.

  8. Adaptive Lighting

    OpenAIRE

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive LightingAdaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled i...

  9. Light Reflector

    Science.gov (United States)

    1988-01-01

    Ultra Sales, Inc.'s fluorescent lighting fixture gets a boost in reflectivity through installation of Lightdriver, a thin tough thermoplastic film plated with aluminum, capable of reflecting 95 percent of visible light striking it. Lightdriver increases brightness without adding bulbs, and allows energy savings by removing some bulbs because the mirrorlike surface cuts light loss generally occasioned by conventional low reflectivity white painted surface above the bulbs in many fluorescent fixtures. Forty-five percent reduction in lighting electricity is attainable.

  10. LA Palma Night-Sky Brightness

    CERN Document Server

    Benn, C R; Benn, Chris R.; Ellison, Sara L.

    1998-01-01

    The brightness of the moonless night sky above La Palma was measured on 427 CCD images taken with the Isaac Newton and Jacobus Kapteyn Telescopes on 63 nights during 1987 - 1996. The median sky brightness at high elevation, high galactic latitude and high ecliptic latitude, at sunspot minimum, is B = 22.7, V = 21.9, R = 21.0, similar to that at other dark sites. The main contributions to sky brightness are airglow and zodiacal light. The sky is brighter at low ecliptic latitude (by 0.4 mag); at solar maximum (by 0.4 mag); and at high airmass (0.25 mag brighter at airmass 1.5). Light pollution (line + continuum) contributes < 0.03 mag in U, approximately 0.02 mag in B, approximately 0.10 mag in V, approximately and 0.10 mag in R at the zenith. This paper is a summary of results which are presented in full elsewhere (Benn & Ellison 1998, La Palma Technical Note 115).

  11. Time collimation for elastic neutron scattering at a pulsed source

    International Nuclear Information System (INIS)

    Conditions for carrying out elastic neutron scattering experiments using the time-of-flight technique are considered. It is shown, that the employment of time dependent neutron beam collimation in the source-sample flight path increases the luminosity of the spectrometer under certain resolution restrictions. Time collimation modes are proposed for small-angle scattering and neutron reflection. (author) 8 figs., 3 refs

  12. Towards Optimum Material Choices for HL-LHC Collimator Upgrade

    CERN Document Server

    Quaranta, E.; Biancacci, N.; Bruce, R.; Carra, F.; Métral, E.; Redaelli, S.; Rossi, A.; Salvant, B.

    2016-01-01

    properties that address different limitations of the present collimation system, solutions have been found to fulfil various upgrade challenges. This paper describes the proposed staged approach to deploy new materials in the upgraded HL-LHC collimation system. Beam tests at the CERN HiRadMat facility were also performed to benchmark simulation methods and constitutive material models.

  13. Self-collimation in photonic crystals with anisotropic constituents

    Institute of Scientific and Technical Information of China (English)

    J. W. Haus; M. Siraj; P. Prasad; P. Markowicz

    2007-01-01

    @@ In a photonic crystal composed of anisotropic constituents we quantify the range of input angles and the degree of collimation of the beam inside the crystal. The optical properties of a photobleached 4-dimethylamino-N-methyl-4-stilbazolium-tosylate (DAST) crystal are used in our model to demonstrate the efficacy of the self-collimation features.

  14. Formation of collimated beams behind the woodpile photonic crystal

    International Nuclear Information System (INIS)

    We experimentally observe formation of narrow laser beams behind the woodpile photonic crystal, when the beam remains well collimated in free propagation behind the crystal. We show that the collimation depends on the input laser beam's focusing conditions, and we interpret theoretically the observed effect by calculating the spatial dispersion of propagation eigenmodes and by numerical simulation of paraxial propagation model.

  15. Light

    CERN Document Server

    Robertson, William C

    2003-01-01

    Why is left right and right left in the mirror? Baffled by the basics of reflection and refraction? Wondering just how the eye works? If you have trouble teaching concepts about light that you don t fully grasp yourself, get help from a book that s both scientifically accurate and entertaining with Light. By combining clear explanations, clever drawings, and activities that use easy-to-find materials, this book covers what science teachers and parents need to know to teach about light with confidence. It uses ray, wave, and particle models of light to explain the basics of reflection and refraction, optical instruments, polarization of light, and interference and diffraction. There s also an entire chapter on how the eye works. Each chapter ends with a Summary and Applications section that reinforces concepts with everyday examples. Whether you need a deeper understanding of how light bends or a good explanation of why the sky is blue, you ll find Light more illuminating and accessible than a college textbook...

  16. LVDT Conditioning on the LHC Collimators

    CERN Document Server

    Masi, A; Losito, R; Martino, M

    2008-01-01

    The Position Readout and Survey system of the LHC collimators has to monitor in real time (RT), at a frequency close to 100 Hz, the position of the 555 synchronized axes with an accuracy of 20 mum. Radiation hard Linear Variable Differential Transformers (LVDT) are used as absolute position sensors for their ruggedness, intrinsic accuracy and infinite resolution. Because of the radioactive environment the conditioning electronics is located in safe zones up to 800 m away from the sensors. Under these conditions, standard conditioning techniques cannot guarantee the accuracy requested by this application because of cable impedance, noise immunity, crosstalk between signals of different sensors passing within the same multiwire cable and temperature stability. A fully digital approach based on a sine-fit algorithm has been followed and will be described showing the excellent results measured up to now. Particular attention is devoted to the RT implementation of the algorithm on the PXI platform from National In...

  17. Collimated trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    The objects of this invention are first to reduce the time required to obtain statistically significant data in trans-axial tomographic radioisotope scanning using a scintillation camera. Secondly, to provide a scintillation camera system to increase the rate of acceptance of radioactive events to contribute to the positional information obtainable from a known radiation source without sacrificing spatial resolution. Thirdly to reduce the scanning time without loss of image clarity. The system described comprises a scintillation camera detector, means for moving this in orbit about a cranial-caudal axis relative to a patient and a collimator having septa defining apertures such that gamma rays perpendicular to the axis are admitted with high spatial resolution, parallel to the axis with low resolution. The septa may be made of strips of lead. Detailed descriptions are given. (U.K.)

  18. Collimated trans-axial tomographic scintillation camera

    International Nuclear Information System (INIS)

    The principal problem in trans-axial tomographic radioisotope scanning is the length of time required to obtain meaningful data. Patient movement and radioisotope migration during the scanning period can cause distortion of the image. The object of this invention is to reduce the scanning time without degrading the images obtained. A system is described in which a scintillation camera detector is moved to an orbit about the cranial-caudal axis relative to the patient. A collimator is used in which lead septa are arranged so as to admit gamma rays travelling perpendicular to this axis with high spatial resolution and those travelling in the direction of the axis with low spatial resolution, thus increasing the rate of acceptance of radioactive events to contribute to the positional information obtainable without sacrificing spatial resolution. (author)

  19. Beam diffusion measurements using collimator scans in the LHC

    CERN Document Server

    Valentino, Gianluca; Bruce, Roderik; Burkart, Florian; Previtali, Valentina; Redaelli, Stefano; Salvachua, Belen; Stancari, Giuliov; Valishev, Alexander

    2013-01-01

    The time evolution of beam losses during a collimator scan provides information on halo diffusion and population. This is an essential input for machine performance characterization and for the design of collimation systems. Beam halo measurements in the CERN Large Hadron Collider were conducted through collimator scrapings in a dedicated beam study for the first time at 4 TeV. Four scans were performed with two collimators, in the vertical plane for beam 1 and horizontally for beam 2, before and after bringing the beams into collisions. Inward and outward steps were performed. A diffusion model was used to interpret the observed loss rate evolution in response to the collimator steps. With this technique, diffusion coefficients were estimated as a function of betatron oscillation amplitude from approximately 3 to 7 standard deviations of the transverse beam distribution. A comparison of halo diffusion and core emittance growth rates is also presented.

  20. Modeling and simulation of LHC beam-based collimator setup

    CERN Document Server

    Valentino, G; Assmann, R W; Burkart, F; Redaelli, S; Rossi, A; Lari, L

    2012-01-01

    In the 2011 Large Hadron Collider run, collimators were aligned for proton and heavy ion beams using a semiautomatic setup algorithm. The algorithm provided a reduction in the beam time required for setup, an elimination of beam dumps during setup and better reproducibility with respect to manual alignment. A collimator setup simulator was developed based on a Gaussian model of the beam distribution as well as a parametric model of the beam losses. A time-varying beam loss signal can be simulated for a given collimator movement into the beam. The simulation results and comparison to measurement data obtained during collimator setups and dedicated fills for beam halo scraping are presented. The simulator will then be used to develop a fully automatic collimator alignment algorithm.

  1. Preliminary Exploratory Study of Different Phase II Collimators

    CERN Document Server

    Lari, L; Bertarelli, A; Bracco, C; Brugger, M; Cerutti, F; Dallocchio, Alessandro; Doyle, E; Ferrari, A; Keller, L; Lundgren, S; Markiewicz, T; Mauri, M; Roesler, S; Sarchiapone, L; Smith, J; Vlachoudis, V

    2008-01-01

    The LHC collimation system is installed and commissioned in different phases, following the natural evolution of the LHC performance. To improve cleaning efficiency towards the end of the low beta squeeze at 7TeV, and in stable physics conditions, it is foreseen to complement the 30 highly robust Phase I secondary collimators with low impedance Phase II collimators. At this stage, their design is not yet finalized. Possible options include metallic collimators, graphite jaws with a movable metallic foil, or collimators with metallic rotating jaws. As part of the evaluation of the different designs, the FLUKA Monte Carlo code is extensively used for calculating energy deposition and studying material damage and activation. This report outlines the simulation approach and defines the critical quantities involved.

  2. Ultra-compact on-chip LED collimation optics by 3D femtosecond direct laser writing.

    Science.gov (United States)

    Thiele, Simon; Gissibl, Timo; Giessen, Harald; Herkommer, Alois M

    2016-07-01

    By using two-photon lithographic 3D printing, we demonstrate additive manufacturing of a dielectric concentrator directly on a LED chip. With a size of below 200 μm in diameter and length, light output is increased by a factor of 6.2 in collimation direction, while the emission half-angle is reduced by 50%. We measure excellent form fidelity and irradiance patterns close to simulation. Additionally, a more complex shape design is presented, which exhibits a nonconventional triangular illumination pattern. The introduced method features exceptional design freedoms which can be used to tailor high-quality miniature illumination optics for specific lighting tasks, for example, endoscopy. PMID:27367093

  3. X-ray collimation by the parabolic cylinder mirror in SPring-8/BL29XUL.

    Science.gov (United States)

    Takei, Dai; Kohmura, Yoshiki; Senba, Yasunori; Ohashi, Haruhiko; Tamasaku, Kenji; Ishikawa, Tetsuya

    2016-01-01

    A combination of plane and threefold-shape X-ray mirrors was installed in SPring-8 BL29XUL. The second mirror has parabolic cylinder surfaces that collimate X-rays in the vertical direction. A performance test was conducted, yielding highly collimated 8 keV photon beams with an effective angular divergence of 0.4 µrad, below only 5% of that of the original beams. The double-mirror system preserved 70% of the total incident flux and nearly tripled the flux density at 988 m from the light source. The values of the observations were almost similar to those of our ray-tracing simulation. Based on the results a discussion of future prospects of the mirror system is included.

  4. Polarization-independent self-collimating bends and beam splitters in photonic crystals

    Institute of Scientific and Technical Information of China (English)

    Xiaopeng Shen; Kui Han; Xianqing Yang; Yifeng Shen; Haipeng Li; Gang Tang; Zhitian Guo

    2007-01-01

    Polarization independent bends and beam splitters for transverse electric (TE) and transverse magnetic (TM) polarizations have been demonstrated in two-dimensional (2D) photonic crystals (PhCs). In virtuel of equi-frequency contour analysis and finite-difference time-domain calculations, self-collimation behaviors for TE- and TM-polarizations are achieved at the same frequency. Simulation results show a 90-degree bend with 90% efficiency and beam splitters with about 96% total efficiency for both TE- and TMpolarizations, where the light is self-guided by the self-collimation effect. Such bends and beam splitters are expected to play important roles in optical devices where polarization insensitivity is needed.

  5. Determination of optimal collimation parameters for a rotating slat collimator system: a system matrix method using ML-EM

    Science.gov (United States)

    Boisson, F.; Bekaert, V.; Brasse, D.

    2016-03-01

    Nowadays, Single Photon imaging has become an essential part of molecular imaging and nuclear medicine. Whether to establish a diagnosis or in the therapeutic monitoring, this modality presents performance that continues to improve. For over 50 years, several collimators have been proposed. Mainly governed by collimation parameters, the resolution-sensitivity trade-off is the factor determining the collimator the most suitable for an intended study. One alternative to the common approaches is the rotating slat collimator (RSC). In the present study, we are aiming at developing a preclinical system equipped with a RSC dedicated to mice and rats imaging, which requires both high sensitivity and spatial resolution. We investigated the resolution-sensitivity trade-offs obtained by varying different collimation parameters: (i) the slats height (H), and (ii) the gap between two consecutive slats (g), considering different intrinsic spatial resolutions. One system matrix was generated for each set of collimation parameters (H,g). Spatial resolutions, Signal-to-Noise Ratio (SNR) and sensitivity obtained for all the set of collimation parameters (H,g) were measured in the 2D projections reconstructed with ML-EM. According to our results, 20 mm high slats and a 1 mm gap were chosen as a good RSC candidate for a preclinical detection module. This collimator will ensure a sensitivity greater than 0.2% and a system spatial resolution below 1 mm, considering an intrinsic spatial resolution below 0.8 mm.

  6. COLLIMATION AND SCATTERING OF THE ACTIVE GALACTIC NUCLEUS EMISSION IN THE SOMBRERO GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Menezes, R. B.; Steiner, J. E.; Ricci, T. V., E-mail: robertobm@astro.iag.usp.br [Instituto de Astronomia Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, Sao Paulo, SP CEP 05508-090 (Brazil)

    2013-03-10

    We present an analysis of a data cube of the central region of M104, the Sombrero galaxy, obtained with the GMOS-IFU of the Gemini-South telescope, and report the discovery of collimation and scattering of the active galactic nucleus (AGN) emission in the circumnuclear region of this galaxy. Analysis with PCA Tomography and spectral synthesis revealed the existence of collimation and scattering of the AGN featureless continuum and also of a broad component of the H{alpha} emission line. The collimation and scattering of this broad H{alpha} component was also revealed by fitting the [N II] {lambda}{lambda}6548, 6583 and H{alpha} emission lines as a sum of Gaussian functions. The spectral synthesis, together with a V-I image obtained with the Hubble Space Telescope, showed the existence of circumnuclear dust, which may cause the light scattering. We also identify a dusty feature that may be interpreted as a torus/disk structure. The existence of two opposite regions with featureless continuum (P.A. = -18 Degree-Sign {+-} 13 Degree-Sign and P.A. = 162 Degree-Sign {+-} 13 Degree-Sign ) along a direction perpendicular to the torus/disk (P.A. = 72 Degree-Sign {+-} 14 Degree-Sign ) suggests that this structure is approximately edge-on and collimates the AGN emission. The edge-on torus/disk also hides the broad-line region. The proposed scenario is compatible with the unified model and explains why only a weak broad component of the H{alpha} emission line is visible and also why many previous studies detected no broad H{alpha}. The technique used here proved to be an efficient method not only for detecting scattered light, but also for testing the unified model in low-luminosity AGNs.

  7. Assessment of line of sight characteristics of ITER bolometer prototype collimators

    Energy Technology Data Exchange (ETDEWEB)

    Penzel, F., E-mail: florian.penzel@ipp.mpg.de [Max-Planck-Institute for Plasmaphysics, EURATOM Association, Garching (Germany); Meister, H.; Giannone, L.; Kannamüller, M.; Koll, J.; Trautmann, T. [Max-Planck-Institute for Plasmaphysics, EURATOM Association, Garching (Germany); Koch, A.W. [Institute for Measurement Systems and Sensor Technology, Technical University of Munich (Germany)

    2013-10-15

    Highlights: ► Developments on the optimization of line of sight (LOS) characteristics for the ITER bolometry collimators are presented. ► ITER Bolometer Robot Test Facility (IBOROB) is used as a diagnostic tool in order to analyze signal geometry and assess the performance of different prototypes. ► LOS characteristics as a function of number of apertures are presented. ► Influence of a microwave filtering aperture was determined. ► Improvement of stray light attenuation by application of the graphite based coating AQUADAG. -- Abstract: This work outlines the present design status of developments on the optimization of line of sight (LOS) characteristics for the ITER bolometry collimators. The verification and measurement of the LOS of the bolometry is an important issue for a reliable operation of the tomographic reconstruction algorithms. Therefore the ITER Bolometer Robot Test Facility (IBOROB) is used as a diagnostic tool in order to analyze LOS geometry and assess the performance of different collimator prototypes. The LOS characteristics as a function of number of apertures are presented and the influence of a microwave filtering aperture was determined. The results of the improvement of stray light attenuation by application of the graphite based coating AQUADAG are evaluated as well and an overview about the current collimator design is given. This paper focuses on the most remarkable results, a way to further possible upgrades is outlined. However, some results are not in accordance with the ones predicted in theoretical calculations. Thus not all key parameters which influence the LOS could be clearly identified yet.

  8. Assessment of line of sight characteristics of ITER bolometer prototype collimators

    International Nuclear Information System (INIS)

    Highlights: ► Developments on the optimization of line of sight (LOS) characteristics for the ITER bolometry collimators are presented. ► ITER Bolometer Robot Test Facility (IBOROB) is used as a diagnostic tool in order to analyze signal geometry and assess the performance of different prototypes. ► LOS characteristics as a function of number of apertures are presented. ► Influence of a microwave filtering aperture was determined. ► Improvement of stray light attenuation by application of the graphite based coating AQUADAG. -- Abstract: This work outlines the present design status of developments on the optimization of line of sight (LOS) characteristics for the ITER bolometry collimators. The verification and measurement of the LOS of the bolometry is an important issue for a reliable operation of the tomographic reconstruction algorithms. Therefore the ITER Bolometer Robot Test Facility (IBOROB) is used as a diagnostic tool in order to analyze LOS geometry and assess the performance of different collimator prototypes. The LOS characteristics as a function of number of apertures are presented and the influence of a microwave filtering aperture was determined. The results of the improvement of stray light attenuation by application of the graphite based coating AQUADAG are evaluated as well and an overview about the current collimator design is given. This paper focuses on the most remarkable results, a way to further possible upgrades is outlined. However, some results are not in accordance with the ones predicted in theoretical calculations. Thus not all key parameters which influence the LOS could be clearly identified yet

  9. Theoretical analysis of a collimated hollow-laser-beam generated by a single axicon using diffraction integral

    Institute of Scientific and Technical Information of China (English)

    Yong Qian(钱勇); Yuzhu Wang(王育竹)

    2004-01-01

    A novel method to generate a collimated hollow-laser-beam (HLB) by only a single axicon is proposed. With some reasonable assumptions, the radial light intensity distribution is calculated in detail by diffraction integral theory. The result of numerical simulation shows that this method is valid. Compared with other methods of generating HLB, this scheme is extraordinarily simple in principle and can be utilized experimentally to construct a light trap in atomic fountain for convenience.

  10. Light

    CERN Document Server

    Ditchburn, R W

    2011-01-01

    This classic study, available for the first time in paperback, clearly demonstrates how quantum theory is a natural development of wave theory, and how these two theories, once thought to be irreconcilable, together comprise a single valid theory of light. Aimed at students with an intermediate-level knowledge of physics, the book first offers a historical introduction to the subject, then covers topics such as wave theory, interference, diffraction, Huygens' Principle, Fermat's Principle, and the accuracy of optical measurements. Additional topics include the velocity of light, relativistic o

  11. Multipinhole collimator with 20 apertures for a brain SPECT application

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tzu-Cheng; Ellin, Justin R.; Shrestha, Uttam; Seo, Youngho, E-mail: youngho.seo@ucsf.edu [Physics Research Laboratory, Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94107 (United States); Huang, Qiu [School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China); Gullberg, Grant T. [Department of Radiotracer Development and Imaging Technology, Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94702 (United States)

    2014-11-01

    Purpose: Several new technologies for single photon emission computed tomography (SPECT) instrumentation with parallel-hole collimation have been proposed to improve detector sensitivity and signal collection efficiency. Benefits from improved signal efficiency include shorter acquisition times and lower dose requirements. In this paper, the authors show a possibility of over an order of magnitude enhancement in photon detection efficiency (from 7.6 × 10{sup −5} to 1.6 × 10{sup −3}) for dopamine transporter (DaT) imaging of the striatum over the conventional SPECT parallel-hole collimators by use of custom-designed 20 multipinhole (20-MPH) collimators with apertures of 0.75 cm diameter. Methods: Quantifying specific binding ratio (SBR) of {sup 123}I-ioflupane or {sup 123}I-iometopane’s signal at the striatal region is a common brain imaging method to confirm the diagnosis of the Parkinson’s disease. The authors performed imaging of a striatal phantom filled with aqueous solution of I-123 and compared camera recovery ratios of SBR acquired between low-energy high-resolution (LEHR) parallel-hole collimators and 20-MPH collimators. Results: With only two-thirds of total acquisition time (20 min against 30 min), a comparable camera recovery ratio of SBR was achieved using 20-MPH collimators in comparison to that from the LEHR collimator study. Conclusions: Their systematic analyses showed that the 20-MPH collimator could be a promising alternative for the DaT SPECT imaging for brain over the traditional LEHR collimator, which could give both shorter scan time and improved diagnostic accuracy.

  12. High brightness microwave lamp

    Science.gov (United States)

    Kirkpatrick, Douglas A.; Dolan, James T.; MacLennan, Donald A.; Turner, Brian P.; Simpson, James E.

    2003-09-09

    An electrodeless microwave discharge lamp includes a source of microwave energy, a microwave cavity, a structure configured to transmit the microwave energy from the source to the microwave cavity, a bulb disposed within the microwave cavity, the bulb including a discharge forming fill which emits light when excited by the microwave energy, and a reflector disposed within the microwave cavity, wherein the reflector defines a reflective cavity which encompasses the bulb within its volume and has an inside surface area which is sufficiently less than an inside surface area of the microwave cavity. A portion of the reflector may define a light emitting aperture which extends from a position closely spaced to the bulb to a light transmissive end of the microwave cavity. Preferably, at least a portion of the reflector is spaced from a wall of the microwave cavity. The lamp may be substantially sealed from environmental contamination. The cavity may include a dielectric material is a sufficient amount to require a reduction in the size of the cavity to support the desired resonant mode.

  13. Wavelength division demultiplexing with photonic crystal self-collimation interference

    Science.gov (United States)

    Wang, Yufei; Qiu, Yishen; Chen, Xiyao; Lin, Guimin; Hong, Hailian

    2007-11-01

    A theoretical model of wavelength division demultiplexer (WDD), which is based on an asymmetric Mach-Zehnder interferometer (AMZI) constructed in a two-dimensional photonic crystal (2D PhC), is proposed and numerically demonstrated. The 2D PhC consists of a square lattice of cylindric air holes in silicon. The AMZI includes two mirrors and two splitters. Lights propagate between them employing self-collimation effect. The two interferometer branches have different path lengths. By using the finite-difference time-domain method, the calculation results show that the transmission spectras at two AMZI output ports are in the shape of sinusoidal curves and have a uniform peak spacing in the frequency range from 0.26c/a to 0.27c/a. When the path length of the longer branch is increased and the shorter one is fixed, the peaks shift to the lower frequencies and the peak spacing decreases nonlinearly. Consequently, the transmission can be designed to meet various application demands by changing the length difference between the two branches. For the dimensions of the WDD are about tens of operating wavelengths, this PhC WDD may be applied in future photonic integrated circuits.

  14. Studies for an alternative LHC non-linear collimation system

    CERN Document Server

    Lari, L; Boccone, V; Cerutti, F; Versaci, R; Vlachoudis, V; Mereghetti, A; Faus-Golfe, A; Resta-Lopez, J

    2012-01-01

    A LHC non-linear betatron cleaning collimation system would allow larger gap for the mechanical jaws, reducing as a consequence the collimator-induced impedance, which may limit the LHC beam intensity. In this paper, the performance of the proposed system is analyzed in terms of beam losses distribution around the LHC ring and cleaning efficiency in stable physics condition at 7TeV for Beam1. Moreover, the energy deposition distribution on the machine elements is compared to the present LHC Betatron cleaning collimation system in the Point 7 Insertion Region (IR).

  15. Tracking studies of the Compact Linear Collider collimation system

    Energy Technology Data Exchange (ETDEWEB)

    Agapov, I.; Burkhardt, H.; Schulte, D.; /CERN; Latina, A.; /Fermilab; Blair, G.A.; Malton, S.; /Royal Holloway, U. of London; Resta-Lopez, J.; /Oxford U., JAI

    2009-08-01

    A collimation system performance study includes several types of computations performed by different codes. Optics calculations are performed with codes such as MADX, tracking studies including additional effects such as wakefields, halo and tail generation, and dynamical machine alignment are done with codes such as PLACET, and energy deposition can be studied with BDSIM. More detailed studies of hadron production in the beam halo interaction with collimators are better performed with GEANT4 and FLUKA. A procedure has been developed that allows one to perform a single tracking study using several codes simultaneously. In this paper we study the performance of the Compact Linear Collider collimation system using such a procedure.

  16. The optimisation of absorber thickness for neutron Soller slit collimators

    Energy Technology Data Exchange (ETDEWEB)

    Cussen, L.D. [Victoria Univ. of Technol., Melbourne (Australia). Sch. of Commun. and Inf.

    1998-08-11

    When constructing neutron Soller slit collimators an absorbing layer is applied to the blades. Choice of an optimum absorber thickness becomes more important as the collimator is made shorter or the neutron absorption becomes poorer as occurs for short wavelength neutrons. A quality factor for the performance of Soller slit collimators is proposed and used to determine the optimum thickness of the absorbing layer. The solution to this problem is non analytic but easily coded as a computer program. Sample calculations of optimum thickness are described. A simple formula for the approximate optimum thickness is given. (orig.) 3 refs.

  17. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G.; Kuznetsov, G.; Shiltsev, V.; Still, D.A.; Valishev, A.; Vorobiev, L.G.; Assmann, R.; Kabantsev, A.

    2010-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams

  18. Hollow Electron Beam Collimator: R&D Status Report

    CERN Document Server

    Stancari, G; Kuznetsov, G; Shiltsev, V; Valishev, A; Kabantsev, A; Vorobiev, L

    2012-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams.

  19. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G; Kuznetsov, G; Shiltsev, V; Still, D A; Valishev, A; Vorobiev, L G; Assmann, R; Kabantsev, A

    2012-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams.

  20. Independent collimators are sufficient to conform and combine adjacent fields?

    International Nuclear Information System (INIS)

    Consider a radiotherapy treatment in which the tumor is located in the region of head and neck. In general, isocentric technique combined with three tangents half-beam fields are used. How these fields must be collimated? We show that the combination of independent collimators and multi-leaf results in a uniform dose in the region which these fields touch each other. Moreover, we recommend a setup that minimizes the heterogeneity for LINAC's that doesn't possess a multi-leaf collimator. (author)

  1. The final collimator has been installed ready for the LHC restart (phase 1 of the LHC collimator project)

    CERN Multimedia

    CERN audiovisual service

    2009-01-01

    The collimators are installed around the LHC ring and the transfer lines to absorb ‘stray’ particles that have spread out, forming a halo around the beam. It is important to absorb this halo to protect the rest of the machine from damage, in particular the superconducting magnets, where any slight heating by the ‘stray particles’ could cause a magnet quench. The one-meter long collimators absorb the particles in the halo by closing a set of ‘jaws’ of various materials around the beam; the most robust collimators use fiber-reinforced graphite. Before the start-up last year, 88 collimators were installed. The unforeseen shutdown caused by the incident in Sector 3-4, allowed the collimator team to continue with the final 20 collimators necessary to maximize the LHC intensity and luminosity reach with the phase 1 collimation system. This marks the end of 6.5 years of hard work since the project began

  2. Self-collimation-based photonic crystal Mach–Zehnder add-drop filters

    International Nuclear Information System (INIS)

    Photonic crystal Mach–Zehnder add-drop filters (PC-MZADFs) based on the self-collimation phenomenon in a two-dimensional (2D) PC are proposed and numerically studied using finite-difference time-domain (FDTD) simulations. Each PC-MZADF is composed of a symmetric Mach–Zehnder interferometer (MZI) with an identical filter in each of its two different optical paths. Zizag-box resonators (ZBRs) and Fano resonators (FRs) are employed as the optical filters in rod-type and hole-type PCs, respectively. It is shown that self-collimated beams with the ZBR and FR resonant frequencies can be dropped or added using multiple-beam interference. We also show that the resonant frequencies of the resonators can be adjusted by varying the radii of their rods or holes. Our results indicate that this device design may constitute an efficient approach to light propagation manipulation and increase the application range of self-collimated beams. (paper)

  3. Self-collimation-based photonic crystal Mach-Zehnder add-drop filters

    Science.gov (United States)

    Lee, Sun-Goo; Park, Jong-Moon; Kee, Chul-Sik; Lee, Jongjin

    2016-02-01

    Photonic crystal Mach-Zehnder add-drop filters (PC-MZADFs) based on the self-collimation phenomenon in a two-dimensional (2D) PC are proposed and numerically studied using finite-difference time-domain (FDTD) simulations. Each PC-MZADF is composed of a symmetric Mach-Zehnder interferometer (MZI) with an identical filter in each of its two different optical paths. Zizag-box resonators (ZBRs) and Fano resonators (FRs) are employed as the optical filters in rod-type and hole-type PCs, respectively. It is shown that self-collimated beams with the ZBR and FR resonant frequencies can be dropped or added using multiple-beam interference. We also show that the resonant frequencies of the resonators can be adjusted by varying the radii of their rods or holes. Our results indicate that this device design may constitute an efficient approach to light propagation manipulation and increase the application range of self-collimated beams.

  4. Beam Loss Patterns at the LHC Collimators Measurements & Simulations

    CERN Document Server

    Böhlen, Till Tobias

    2008-01-01

    The Beam Loss Monitoring (BLM) system of the Large Hadron Collider (LHC) detects particle losses of circulating beams and initiates an emergency extraction of the beam in case that the BLM thresholds are exceeded. This protection is required as energy deposition in the accelerator equipment due to secondary shower particles can reach critical levels; causing damage to the beam-line components and quenches of superconducting magnets. Robust and movable beam line elements, so-called collimators, are the aperture limitations of the LHC. Consequently, they are exposed to the excess of lost beam particles and their showers. Proton loss patterns at LHC collimators have to be determined to interpret the signal of the BLM detectors and to set adequate BLM thresholds for the protection of collimators and other equipment in case of unacceptably increased loss rates. The first part of this work investigates the agreement of BLM detector measurements with simulations for an LHC-like collimation setup. The setup consists ...

  5. Beam Loss and Beam Shape at the LHC Collimators

    CERN Document Server

    Burkart, Florian

    In this master thesis the beam loss and the beam shape at the LHC collimators was measured, analysed, presented and discussed. Beginning with a short introduction of the LHC, the experiments, the supercon- ducting magnet system, the basics on linear beam dynamics and a describtion of the LHC collimation system are given. This is followed by the presentation of the performance of the LHC collimation sys- tem during 2011. A method to convert the Beam Loss Monitor signal in Gy/s to a proton beam loss rate will be introduced. Also the beam lifetime during the proton physics runs in 2011 will be presented and discussed. Finally, the shape of the LHC beams is analysed by using data obtained by scraping the beam at the LHC primary collimators.

  6. Mechanical Design for Robustness of the LHC Collimators

    CERN Document Server

    Bertarelli, Alessandro; Assmann, R W; Calatroni, Sergio; Dallocchio, Alessandro; Kurtyka, Tadeusz; Mayer, Manfred; Perret, Roger; Redaelli, Stefano; Robert-Demolaize, Guillaume

    2005-01-01

    The functional specification of the LHC Collimators requires, for the start-up of the machine and the initial luminosity runs (Phase 1), a collimation system with maximum robustness against abnormal beam operating conditions. The most severe cases to be considered in the mechanical design are the asynchronous beam dump at 7 TeV and the 450 GeV injection error. To ensure that the collimator jaws survive such accident scenarios, low-Z materials were chosen, driving the design towards Graphite or Carbon/Carbon composites. Furthermore, in-depth thermo-mechanical simulations, both static and dynamic, were necessary.This paper presents the results of the numerical analyses performed for the 450 GeV accident case, along with the experimental results of the tests conducted on a collimator prototype in Cern TT40 transfer line, impacted by a 450 GeV beam of 3.1·1013

  7. Errors generated with the use of rectangular collimation

    Energy Technology Data Exchange (ETDEWEB)

    Parks, E.T. (Department of Allied Health, Western Kentucky University, Bowling Green (USA))

    1991-04-01

    This study was designed to determine whether various techniques for achieving rectangular collimation generate different numbers and types of errors and remakes and to determine whether operator skill level influences errors and remakes. Eighteen students exposed full-mouth series of radiographs on manikins with the use of six techniques. The students were grouped according to skill level. The radiographs were evaluated for errors and remakes resulting from errors in the following categories: cone cutting, vertical angulation, and film placement. Significant differences were found among the techniques in cone cutting errors and remakes, vertical angulation errors and remakes, and total errors and remakes. Operator skill did not appear to influence the number or types of errors or remakes generated. Rectangular collimation techniques produced more errors than did the round collimation techniques. However, only one rectangular collimation technique generated significantly more remakes than the other techniques.

  8. Benchmarking of collimation tracking using RHIC beam loss data.

    Energy Technology Data Exchange (ETDEWEB)

    Robert-Demolaize,G.; Drees, A.

    2008-06-23

    State-of-the-art tracking tools were recently developed at CERN to study the cleaning efficiency of the Large Hadron Collider (LHC) collimation system. In order to estimate the prediction accuracy of these tools, benchmarking studies can be performed using actual beam loss measurements from a machine that already uses a similar multistage collimation system. This paper reviews the main results from benchmarking studies performed with specific data collected from operations at the Relativistic Heavy Ion Collider (RHIC).

  9. Formation of collimated beams behind the woodpile photonic crystal

    OpenAIRE

    Trull Silvestre, José Francisco; Maigyte, Lina; Malinauskas, Mangirdas; Mizeikis, Vygantas; Juodkazis, Saulius; Cojocaru, Crina; Rutkauskas, Marius; Peckus, Martynas; Sirutkaitis, Valdas; Staliunas, Kestutis

    2011-01-01

    We experimentally observe formation of narrow laser beams behind the woodpile photonic crystal, when the beam remains well collimated in free propagation behind the crystal. We show that the collimation depends on the input laser beam’s focusing conditions, and we interpret theoretically the observed effect by calculating the spatial dispersion of propagation eigenmodes and by numerical simulation of paraxial propagation model. Peer Reviewed

  10. Collimated directional emission from a peanut-shaped microresonator

    OpenAIRE

    Shu, Fang-Jie; Zou, Chang-Ling; Sun, Fang-Wen; Xiao, Yun-Feng

    2011-01-01

    Collimated directional emission is essentially required an asymmetric resonant cavity. In this paper, we theoretically investigate a type of peanut-shaped microcavity which can support highly directional emission with the emission divergence as small as 2.5o. The mechanism of the collimated emission is explained with the short-term ray trajectory and the intuitive lens model in detail. Wave simulation also confirms these results. This extremely narrow divergence of the emission holds a great ...

  11. Steering and collimating ballistic electrons with amphoteric refraction

    International Nuclear Information System (INIS)

    We show that amphoteric refraction of ballistic electrons, i.e., positive or negative refraction depending on the incidence angle, occurs at an interface between an isotropic and an anisotropic medium and can be employed to steer and collimate electron beams. The steering angle is determined by the materials’ parameters, but the degree of collimation can be tuned in a significant range by changing the energy of ballistic electrons.

  12. Parallel-hole collimator concept for stationary SPECT imaging

    Science.gov (United States)

    Pato, Lara R. V.; Vandenberghe, Stefaan; Zedda, Tiziana; Van Holen, Roel

    2015-11-01

    Parallel-hole SPECT collimators have traditionally been manufactured by stacking sheets of lead foil or by casting. These techniques significantly restrict our options in terms of collimator geometry. However, recent developments in metal additive manufacturing are making novel collimator designs possible, giving rise to new opportunities in SPECT imaging. In this paper we propose an innovative type of collimator for stationary SPECT, using parallel-holes whose collimation direction depends on their axial position. Its main advantage compared to current stationary SPECT systems (which are based on pinholes) is that, using only axial bed translations, we can achieve complete angular sampling of an increased portion of the transaxial area of the collimator bore. This allows the system to be much more compact than current stationary SPECT systems that image objects of the same size. We describe three possible designs, for full-body, brain and small-animal imaging, respectively, and test their feasibility using simulations. The system modeling method is validated against realistic Monte Carlo simulations, and then used in the evaluation of the systems’ performances and reconstructions. The simulations show that the system is able to reconstruct objects occupying the predicted field of view (75% of the transaxial area of the bore) without sampling artifacts. In particular, we perform reconstructions from noisy projection data obtained for an activity and scanning time similar to standard protocols for the three applications, and the resulting images indicate the possibility of using the proposed systems in practice.

  13. Mini-beam collimator applications at the Advanced Photon Source

    Energy Technology Data Exchange (ETDEWEB)

    Xu Shenglan, E-mail: sxu@anl.gov [GM/CA CAT, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Keefe, Lisa J.; Mulichak, Anne [IMCA CAT, Argonne National Laboratory, Argonne, IL 60439 (United States); Yan Lifen; Alp, Ercan E.; Zhao Jiyong [X-ray Sciences Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Fischetti, Robert F. [GM/CA CAT, Biosciences Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2011-09-01

    In 2007, the General Medicine and Cancer Institutes Collaborative Access Team (GM/CA CAT, Sector 23, Advanced Photon Source) began providing mini-beam collimators to its users. These collimators contained individual, 5- or 10-{mu}m pinholes and were rapidly exchangeable, thereby allowing users to tailor the beam size to their experimental needs. The use of these collimators provided a reduction in background noise, and thus improved the signal-to-noise ratio . Recent improvements in the collimator design include construction of the device from a monolithic piece of molybdenum with multiple pinholes mounted inside . This allows users to select from various size options from within the beamline control software without the realignment that was previously necessary. In addition, a new, 20-{mu}m pinhole has been added to create a 'quad-collimator', resulting in greater flexibility for the users. The mini-beam collimator is now available at multiple crystallographic beamlines and also is a part of the first Moessbauer Microscopic system at sector 3-ID.

  14. Dual self-image technique for beam collimation

    Science.gov (United States)

    Herrera-Fernandez, Jose Maria; Sanchez-Brea, Luis Miguel; Torcal-Milla, Francisco Jose; Morlanes, Tomas; Bernabeu, Eusebio

    2016-07-01

    We propose an accurate technique for obtaining highly collimated beams, which also allows testing the collimation degree of a beam. It is based on comparing the period of two different self-images produced by a single diffraction grating. In this way, variations in the period of the diffraction grating do not affect to the measuring procedure. Self-images are acquired by two CMOS cameras and their periods are determined by fitting the variogram function of the self-images to a cosine function with polynomial envelopes. This way, loss of accuracy caused by imperfections of the measured self-images is avoided. As usual, collimation is obtained by displacing the collimation element with respect to the source along the optical axis. When the period of both self-images coincides, collimation is achieved. With this method neither a strict control of the period of the diffraction grating nor a transverse displacement, required in other techniques, are necessary. As an example, a LED considering paraxial approximation and point source illumination is collimated resulting a resolution in the divergence of the beam of δ φ =+/- 1.57 μ {rad}.

  15. Collimation quench test with 4 TeV proton beams

    CERN Document Server

    Salvachua, B; Cauchi, M; Deboy, D; Hofle, W; Holzer, EB; Jacquet, D; Lari, L; Nebot, E; Mirarchi, D; Quaranta, E; Redaelli, S; Sapinski, M; Schmidt, R; Valentino, G; Valuch, D; Wenniger, J; Wollmann, D; Zerlauth, M; CERN. Geneva. ATS Department

    2014-01-01

    In 2013, at the end of the LHC physics run I, several quench tests took place with the aim to measure the quench limit of the LHC superconducting magnets. The LHC superconducting magnets in the dispersion suppressor of IR7 are the most exposed to beam losses leaking from the betatron collimation system and represent the main limitation for the halo cleaning. A collimation quench test was performed with 4 TeV proton beams to improve the quench limit estimates, which determine the maximum allowed beam loss rate for a given collimation cleaning. The main goal of the collimation quench test was to try to quench the magnets by increasing losses at the collimators. This note describes the procedure during the test and the first results with the data. Losses of up to 1 MW over a few seconds were generated by blowing up the beam, achieving total losses of about 5.8 MJ. These controlled losses exceeded by a factor 2 the collimation design value, and the magnets did not quench.

  16. Therapy simulation of MLC-collimated fields

    International Nuclear Information System (INIS)

    In clinical routines X-ray simulation of planned treatment fields is performed prior to start of the actual treatment session. In a clinic with access to MLC collimated beams and CT-based patient data in a 3-D dose planning system the beam shaping will in most cases be performed in the dose planning system. In these cases the beam simulation prior to treatment is motivated by at least three reasons. The first is to verify the positioning of the patient relative the beam isocenter point. The second is to verify the field shape with respect to tumour and critical organs, and to have the possibility to use contrast media in this verification. The third reason could be to achieve a reference image for later comparison to portal images. There are alternative methods available to achieve the above stated objects but they often suffer from a number of limitations. A portal imaging system can sometimes fulfil both the positioning and field shaping criteria but lack the contrast of a simulator image and can not be used with contrast media. Digitally reconstructed images can be generated in most dose planning systems and could thus be a potential replacement for simulator images but will not verify the patient position. Thus in most cases there will be an actual need for X-ray simulation prior to the patient treatment and for this purpose a number of different methods to visualise an MLC-shaped beam are available. One method is based on manual transfer of the field shape to the X-ray film. Another, commercially available system utilises automatic transfer of the field contour to a digitized image and a third method which will be presented in more detail is based on a specially developed mechanical accessory to the X-ray simulator, the MLC-delineator

  17. Collimation of a thulium atomic beam by two-dimensional optical molasses

    International Nuclear Information System (INIS)

    The number of laser cooled and trapped thulium atoms in a magneto-optical trap is increased by a factor of 3 using a two-dimensional optical molasses which collimated the atomic beam before entering a Zeeman slower. A diode laser operating at 410.6 nm was employed to form optical molasses: The laser was heated to 70 °C by a two-step temperature stabilisation system. The laser system consisting of a master oscillator and an injection-locked amplifier emitted more than 100 mW at 410 nm and had a spectral linewidth of 0.6 MHz. (extreme light fields and their applications)

  18. Collimation of a thulium atomic beam by two-dimensional optical molasses

    Energy Technology Data Exchange (ETDEWEB)

    Sukachev, D D; Kalganova, E S; Sokolov, A V; Savchenkov, A V; Vishnyakova, G A; Golovizin, A A; Akimov, A V; Kolachevsky, Nikolai N; Sorokin, Vadim N

    2013-04-30

    The number of laser cooled and trapped thulium atoms in a magneto-optical trap is increased by a factor of 3 using a two-dimensional optical molasses which collimated the atomic beam before entering a Zeeman slower. A diode laser operating at 410.6 nm was employed to form optical molasses: The laser was heated to 70 Degree-Sign C by a two-step temperature stabilisation system. The laser system consisting of a master oscillator and an injection-locked amplifier emitted more than 100 mW at 410 nm and had a spectral linewidth of 0.6 MHz. (extreme light fields and their applications)

  19. Enhanced PET resolution by combining pinhole collimation and coincidence detection.

    Science.gov (United States)

    DiFilippo, Frank P

    2015-10-21

    Spatial resolution of clinical PET scanners is limited by detector design and photon non-colinearity. Although dedicated small animal PET scanners using specialized high-resolution detectors have been developed, enhancing the spatial resolution of clinical PET scanners is of interest as a more available alternative. Multi-pinhole 511 keV SPECT is capable of high spatial resolution but requires heavily shielded collimators to avoid significant background counts. A practical approach with clinical PET detectors is to combine multi-pinhole collimation with coincidence detection. In this new hybrid modality, there are three locations associated with each event, namely those of the two detected photons and the pinhole aperture. These three locations over-determine the line of response and provide redundant information that is superior to coincidence detection or pinhole collimation alone. Multi-pinhole collimation provides high resolution and avoids non-colinearity error but is subject to collimator penetration and artifacts from overlapping projections. However the coincidence information, though at lower resolution, is valuable for determining whether the photon passed near a pinhole within the cone acceptance angle and for identifying through which pinhole the photon passed. This information allows most photons penetrating through the collimator to be rejected and avoids overlapping projections. With much improved event rejection, a collimator with minimal shielding may be used, and a lightweight add-on collimator for high resolution imaging is feasible for use with a clinical PET scanner. Monte Carlo simulations were performed of a (18)F hot rods phantom and a 54-pinhole unfocused whole-body mouse collimator with a clinical PET scanner. Based on coincidence information and pinhole geometry, events were accepted or rejected, and pinhole-specific crystal-map projections were generated. Tomographic images then were reconstructed using a conventional pinhole SPECT

  20. Comparative efficiency of the multi-leaf collimator and variable-aperture collimator in intensity-modulated radiotherapy

    Science.gov (United States)

    Anderson, J. W.; Symonds-Tayler, R.; Hartmann, G.; Echner, G.; Lang, C.; Schlegel, W.; Webb, S.

    2006-04-01

    The potential of the variable-aperture collimator (VAC) in intensity-modulated radiation therapy (IMRT) has been evaluated by comparing its performance with that of the multi-leaf collimator (MLC). This comparison used a decomposition algorithm to find the series of collimator segments that would treat a given intensity-modulated beam (IMB). Collimator performance was measured using both the number of segments required to complete the IMB and the monitor-unit efficiency of the treatment. The VAC was modelled with aperture sizes from 4 × 4 cm to 20 × 20 cm, and these apertures were allowed to be located anywhere within the IMB. To enable a direct comparison, a similar scanning MLC was modelled at the same range of aperture sizes. Using both collimators, decompositions were run on 10 × 10 and 20 × 20 random IMBs with integer bixel values ranging from 1 to 10. Clinical IMBs from lung, head and neck, and pelvic patients were taken from a Pinnacle treatment-planning system and tested in the same manner. It was found that for all treatment sites, a small, scanning MLC performs as well or better than an equivalent sized VAC in both number of segments and monitor-unit efficiency, and would be an efficient choice for centres looking for a simple collimator for IMRT.

  1. Quadrature measurements of a bright squeezed state via sideband swapping

    DEFF Research Database (Denmark)

    Schneider, J.; Glockl, O.; Leuchs, G.;

    2009-01-01

    The measurement of an arbitrary quadrature of a bright quantum state of light is a commonly requested action in many quantum information protocols, but it is experimentally challenging with previously proposed schemes. We suggest that the quadrature be measured at a specific sideband frequency of...

  2. The star-bright hour : [luuletused] / Betti Alver

    Index Scriptorium Estoniae

    Alver, Betti, 1906-1989

    2006-01-01

    Sisu: The star-bright hour ; Not a dream ; The Piper ; Corals in an ancent river. Luuletused pärinevad kogumikust "Tuulelaeval valgusest on aerud = Windship with Oars of Light. (Tallinn : Huma, 2001). Orig.: Tähetund ; Mitte viirastus, meelepett ; Vilepuhuja ; Korallid Emajões

  3. Teradiode's high brightness semiconductor lasers

    Science.gov (United States)

    Huang, Robin K.; Chann, Bien; Burgess, James; Lochman, Bryan; Zhou, Wang; Cruz, Mike; Cook, Rob; Dugmore, Dan; Shattuck, Jeff; Tayebati, Parviz

    2016-03-01

    TeraDiode is manufacturing multi-kW-class ultra-high brightness fiber-coupled direct diode lasers for industrial applications. A fiber-coupled direct diode laser with a power level of 4,680 W from a 100 μm core diameter, lasers. The fiber-coupled output corresponds to a Beam Parameter Product (BPP) of 3.5 mm-mrad and is the lowest BPP multi-kW-class direct diode laser yet reported. This laser is suitable for industrial materials processing applications, including sheet metal cutting and welding. This 4-kW fiber-coupled direct diode laser has comparable brightness to that of industrial fiber lasers and CO2 lasers, and is over 10x brighter than state-of-the-art direct diode lasers. We have also demonstrated novel high peak power lasers and high brightness Mid-Infrared Lasers.

  4. The night sky brightness at Potsdam-Babelsberg

    CERN Document Server

    Puschnig, Johannes; Posch, Thomas; Schwarz, Robert

    2013-01-01

    We analyze the results of a 2 years (2011--2012) time series of night sky photometry performed at the Leibniz Institute for Astrophysics in Potsdam (AIP). This observatory is located on top of a hill ("Babelsberg"), 22\\,km to the southwest of the center of Berlin. The measurements have been performed with a Unihedron Sky Quality Meter. We find night sky brightness values ranging from 16.5 to 20.3 mag$_{\\rm SQM}$ arcsec$^{-2}$; the latter (best) value corresponds to 4.7 times the natural zenithal night sky brightness. We discuss the influence of clouds, of the Moon and other factors on the night sky brightness. With respect to the influence of the Moon, it turns out that Potsdam-Babelsberg, despite its proximity to Berlin, still shows a circalunar periodicity of the night sky brightness, although it is much weaker than naturally. The light-pollution-enhancing effect of clouds dominates the night sky brightness by far. Overcast nights with light pollution (up to 16.5 mag$_{\\rm SQM}$ arcsec$^{-2}$) are brighter ...

  5. The EUVE bright source list

    Science.gov (United States)

    Stroozas, B.; Mcdonald, K.; Antia, B.; Mcdonald, J.; Wiercigroch, A.

    1993-01-01

    Initial results for bright extreme ultraviolet sources discovered during the EUVE all-sky and deep ecliptic surveys have been published as a Bright Source List (BSL) and released to the astronomical community with a recent NASA research announcement (NRA 93-OSS-02, Appendix F). This paper describes the data processing software, the EUVE survey data set, and the production of the BSL at the Center for EUV Astrophysics. The contents, format, and selection criteria for sources, the data processing strategy, some problems encountered, and a summary of the BSL results are presented.

  6. All things bright and beautiful

    OpenAIRE

    Brown, Chloe

    2012-01-01

    'All Things Bright and Beautiful' was exhibited in 20/21 Visual Arts Centre, Scunthorpe, which is sited in a 'redundant' church. The fundamental question that the exhibition explored concerned the role of 'the animal' within contemporary art and within secular society, which in turn hoped to prompt reflections on our understanding of the place of 'the human' in the world and in nature. If there is no divine order, as posited by the hymn 'All Things Bright and Beautiful', where does this leave...

  7. Brightness reversal in the natural visual environment: a Venetian blind effect.

    Science.gov (United States)

    Walker, J T

    1985-01-01

    If a partially open Venetian blind is lighted by the sun, or by diffuse light from the sky, then the upper portion of each slat will be brightly lighted and the lower portion shaded. If an observer moves the head downward while viewing a dark object silhouetted against the sky, then the object displays a reversal of brightness, appearing brighter than the sky while the head is moving downward. Moving the head upward produces no brightness reversal. These observations in the natural visual environment are consistent with earlier laboratory demonstration under several conditions. PMID:3832614

  8. Collimated fast electron beam generation in critical density plasma

    International Nuclear Information System (INIS)

    Significantly collimated fast electron beam with a divergence angle 10° (FWHM) is observed when an ultra-intense laser pulse (I = 1014 W/cm2, 300 fs) irradiates a uniform critical density plasma. The uniform plasma is created through the ionization of an ultra-low density (5 mg/c.c.) plastic foam by X-ray burst from the interaction of intense laser (I = 1014 W/cm2, 600 ps) with a thin Cu foil. 2D Particle-In-Cell (PIC) simulation well reproduces the collimated electron beam with a strong magnetic field in the region of the laser pulse propagation. To understand the physical mechanism of the collimation, we calculate energetic electron motion in the magnetic field obtained from the 2D PIC simulation. As the results, the strong magnetic field (300 MG) collimates electrons with energy over a few MeV. This collimation mechanism may attract attention in many applications such as electron acceleration, electron microscope and fast ignition of laser fusion

  9. Radiation shielding for the Main Injector collimation system

    Energy Technology Data Exchange (ETDEWEB)

    Rakhno, Igor; /Fermilab

    2007-12-01

    The results of Monte Carlo radiation shielding studies performed with the MARS15 code for the Main Injector collimation system are presented and discussed. A Proton Plan was developed recently at Fermilab for the benefit of the existing neutrino programs as well as to increase anti-proton production for the Tevatron programs [1]. As a part of the plan, the intensity of proton beams in the Main Injector (MI) should be increased by means of slip-stacking injection. In order to localize beam loss associated with the injection, a collimation system was designed [2] that satisfies all the radiation and engineering constraints. The system itself comprises a primary collimator and four secondary ones to which various masks are added. It is assumed that beam loss at the slip-stacking injection is equal to 5% of total intensity which is 5.5 x 10{sup 13} protons per pulse [2]. As far as pulse separation is 2.2 seconds, one has (5.5 x 10{sup 13}/2.2) x 0.05 = 1.25 x 10{sup 12} protons interacting per second with the primary collimator. In the paper the geometry model of the corresponding MI region and beam loss model are described. The model of the region was built by means of the MAD-MARS Beam Line Builder (MMBLB) [3] using results of the collimation studies [2]. The results of radiation shielding calculations performed with the MARS15 code [4] are presented.

  10. An improved scattering routine for collimation tracking studies at LHC

    CERN Document Server

    Tambasco, Claudia; Salvachua Ferrando, Maria Belen; Cavoto, Gianluca

    The present Master thesis work has been carried out at CERN in the framework of the LHC (Large Hadron Collider) Collimation project. The LHC accelerates proton beams up to 7 TeV colliding in the experiment detectors installed in four points of the accelerator ring. The LHC is built to store a energy of 360MJ for each beam. The energy deposition induced by local beam losses could quench the superconducting magnets located around the accelerator beam pipes. To prevent and keep under control dangerous beam losses, an efficient collimation system is required. In addition, the achievable LHC beam intensity is related to the beam loss rate and, consequently, to the cleaning efficiency of the collimation system. Collimation studies at LHC are carried out also by means of simulations by using SixTrack, a dedicated simulation tool that tracks a large numbers of particles for many turns around the ring. The SixTrack code includes a scattering routine to model proton interactions with the material of the collimators j...

  11. The Crystal Collimation System Of The Relativistic Heavy Ion Collider

    CERN Document Server

    Fliller, R P

    2004-01-01

    Crystal Channeling occurs when an ion enters a crystal with a small angle with respect to the crystal planes. The electrostatic interaction between the incoming ion and the lattice causes the ion to follow the crystal planes. By mechanically bending a crystal, it is possible to use a crystal to deflect ions. One novel use of a bent crystal is to use it to channel beam halo particles into a downstream collimator. By deflecting the halo particles into a collimator with a crystal it may be possible to improve the collimation efficiency as compared to a conventional two stage collimation system. A bent crystal was installed in the counterclockwise ring of the Relativistic Heavy Ion Collider (RHIC) prior to the FY2001 run to be used as the first stage of a two stage collimation system. We present a model and simulations to the predict crystal channeling efficiency. The simulations and model predict a channeling efficiency between 59% and 74% depending on the choice of optics. Attempts to reduce backgrounds in RHIC...

  12. Collimated fast electron beam generation in critical density plasma

    Energy Technology Data Exchange (ETDEWEB)

    Iwawaki, T., E-mail: iwawaki-t@eie.eng.osaka-u.ac.jp; Habara, H.; Morita, K.; Tanaka, K. A. [Graduate School of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565-0871 (Japan); Baton, S.; Fuchs, J.; Chen, S. [LULI, CNRS-Ecole Polytechnique-Université Pierre et Marie Curie-CEA, 91128 Palaiseau (France); Nakatsutsumi, M. [LULI, CNRS-Ecole Polytechnique-Université Pierre et Marie Curie-CEA, 91128 Palaiseau (France); European X-Ray Free-Electron Laser Facility (XFEL) GmbH (Germany); Rousseaux, C. [CEA, DAM, DIF, F-91297 Arpajon (France); Filippi, F. [La SAPIENZA, University of Rome, Dip. SBAI, 00161 Rome (Italy); Nazarov, W. [School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, Fife KY16 9ST, Scotland (United Kingdom)

    2014-11-15

    Significantly collimated fast electron beam with a divergence angle 10° (FWHM) is observed when an ultra-intense laser pulse (I = 10{sup 14 }W/cm{sup 2}, 300 fs) irradiates a uniform critical density plasma. The uniform plasma is created through the ionization of an ultra-low density (5 mg/c.c.) plastic foam by X-ray burst from the interaction of intense laser (I = 10{sup 14 }W/cm{sup 2}, 600 ps) with a thin Cu foil. 2D Particle-In-Cell (PIC) simulation well reproduces the collimated electron beam with a strong magnetic field in the region of the laser pulse propagation. To understand the physical mechanism of the collimation, we calculate energetic electron motion in the magnetic field obtained from the 2D PIC simulation. As the results, the strong magnetic field (300 MG) collimates electrons with energy over a few MeV. This collimation mechanism may attract attention in many applications such as electron acceleration, electron microscope and fast ignition of laser fusion.

  13. Bright Transients discovered by PSST

    Science.gov (United States)

    Smith, K. W.; Wright, D.; Smartt, S. J.; Young, D. R.; Huber, M.; Chambers, K. C.; Flewelling, H.; Willman, M.; Primak, N.; Schultz, A.; Gibson, B.; Magnier, E.; Waters, C.; Tonry, J.; Wainscoat, R. J.; Foley, R. J.; Jha, S. W.; Rest, A.; Scolnic, D.

    2016-08-01

    Six bright transients have been discovered as part of the Pan-STARRS Survey for Transients (PSST). Information on all objects discovered by the Pan-STARRS Survey for Transients is available at http://star.pst.qub.ac.uk/ps1threepi/ (see Huber et al. ATel #7153).

  14. Characteristics of parallel-hole and pinhole collimators for nuclear medicine imaging

    International Nuclear Information System (INIS)

    In this paper, the spatial resolution and geometry sensitivity of parallel- and pin-hole collimators in compact gamma camera are presented, and quantitatively compared by GEANT4 code in Monte-Carlo library. The results show that the geometry sensitivity for pinhole collimator rapidly drops with increasing the gamma source-to- collimator distance (SCD); and for parallel-hole collimator, mildly. Meanwhile, the spatial resolution for pin-hole collimator mildly deteriorates; and for parallel-hole collimator, severely. The pin-hole collimator for close imaging objects has higher geometry sensitivity than parallel-hole collimator. Our findings are helpful for setting compact gamma camera collimators in nuclear medicine imaging. (authors)

  15. Photometric indicators of visual night sky quality derived from all-sky brightness maps

    Science.gov (United States)

    Duriscoe, Dan M.

    2016-09-01

    Wide angle or fisheye cameras provide a high resolution record of artificial sky glow, which results from the scattering of escaped anthropogenic light by the atmosphere, over the sky vault in the moonless nocturnal environment. Analysis of this record yields important indicators of the extent and severity of light pollution. The following indicators were derived through numerical analysis of all-sky brightness maps: zenithal, average all-sky, median, brightest, and darkest sky brightness. In addition, horizontal and vertical illuminance, resulting from sky brightness were computed. A natural reference condition to which the anthropogenic component may be compared is proposed for each indicator, based upon an iterative analysis of a high resolution natural sky model. All-sky brightness data, calibrated in the V band by photometry of standard stars and converted to luminance, from 406 separate data sets were included in an exploratory analysis. Of these, six locations representing a wide range of severity of impact from artificial sky brightness were selected as examples and examined in detail. All-sky average brightness is the most unbiased indicator of impact to the environment, and is more sensitive and accurate in areas of slight to moderate light pollution impact than zenith brightness. Maximum vertical illuminance provides an excellent indicator of impacts to wilderness character, as does measures of the brightest portions of the sky. Zenith brightness, the workhorse of field campaigns, is compared to the other indicators and found to correlate well with horizontal illuminance, especially at relatively bright sites. The median sky brightness describes a brightness threshold for the upper half of the sky, of importance to telescopic optical astronomy. Numeric indicators, in concert with all-sky brightness maps, provide a complete assessment of visual sky quality at a site.

  16. Absolute brightness temperature measurements at 2.1-mm wavelength

    Science.gov (United States)

    Ulich, B. L.

    1974-01-01

    Absolute measurements of the brightness temperatures of the Sun, new Moon, Venus, Mars, Jupiter, Saturn, and Uranus, and of the flux density of DR21 at 2.1-mm wavelength are reported. Relative measurements at 3.5-mm wavelength are also preented which resolve the absolute calibration discrepancy between The University of Texas 16-ft radio telescope and the Aerospace Corporation 15-ft antenna. The use of the bright planets and DR21 as absolute calibration sources at millimeter wavelengths is discussed in the light of recent observations.

  17. Observing the onset of outflow collimation in a massive protostar

    CERN Document Server

    Carrasco-González, C; Cantó, J; Curiel, S; Surcis, G; Vlemmings, W H T; van Langevelde, H J; Goddi, C; Anglada, G; Kim, S -W; Kim, J -S; Gómez, J F

    2015-01-01

    The current paradigm of star formation through accretion disks, and magnetohydrodynamically driven gas ejections, predicts the development of collimated outflows, rather than expansion without any preferential direction. We present radio continuum observations of the massive protostar W75N(B)-VLA 2, showing that it is a thermal, collimated ionized wind and that it has evolved in 18 years from a compact source into an elongated one. This is consistent with the evolution of the associated expanding water-vapor maser shell, which changed from a nearly circular morphology, tracing an almost isotropic outflow, to an elliptical one outlining collimated motions. We model this behavior in terms of an episodic, short-lived, originally isotropic, ionized wind whose morphology evolves as it moves within a toroidal density stratification.

  18. Scraping for LHC and collimation tests in the CERN SPS

    CERN Document Server

    Facchini, M; Gras, J J; Hutchins, S; Jung, R

    2005-01-01

    Scraping of the SPS beam prior to extraction towards the LHC will be important in order to remove the beam tails and ensure clean injection conditions. Scrapers recuperated from the ISR were installed in the SPS for this purpose. The scrapers are associated with a two stage collimation system using collimators previously installed in LEP to reduce the irradiated area in the SPS. Tests have been performed to demonstrate that with the help of these collimators, it is possible to scrape with very little contamination outside the scraping area. Another issue was whether enough time is left for ejection towards the LHC after scraping, before repopulation of the removed tails. This was investigated with the SPS rest gas profile monitor and synchrotron radiation telescope. The system is described and the results of these tests are presented and discussed.

  19. Updated Simulation Studies of Damage Limit of LHC Tertiary Collimators

    CERN Document Server

    AUTHOR|(CDS)2085459; Bertarelli, Alessandro; Bruce, Roderik; Carra, Federico; Cerutti, Francesco; Gradassi, Paolo; Lechner, Anton; Redaelli, Stefano; Skordis, Eleftherios

    2015-01-01

    The tertiary collimators (TCTs) in the LHC, installed in front of the experiments, in standard operation intercept fractions of 10−3 halo particles. However, they risk to be hit by high-intensity primary beams in case of asynchronous beam dump. TCT damage thresholds were initially inferred from results of destructive tests on a TCT jaw, supported by numerical simulations, assuming simplified impact scenarios with one single bunch hitting the jaw with a given impact parameter. In this paper, more realistic failure conditions, including a train of bunches and taking into account the full collimation hierarchy, are used to derive updated damage limits. The results are used to update the margins in the collimation hierarchy and could thus potentially have an influence on the LHC performance.

  20. Comparison of pinhole collimation and focusing optics for SANS

    Energy Technology Data Exchange (ETDEWEB)

    Glinka, C.J., E-mail: cglinka@nist.gov [University of Delaware, Newark, DE 19716 (United States); National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States); Barker, J.G.; Mildner, D.F.R. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

    2015-09-21

    We examine quantitatively the instrumental factors that affect the theoretical performance and practical application of conventional pinhole collimation and focusing optics for small-angle neutron scattering (SANS) measurements. We calculate the relative performance of pinhole collimation vis-à-vis focusing by grazing incidence elliptical mirrors and compare the results with a recent ray-tracing simulation to show that the performance gains due to focusing found in the simulation arise largely from assuming a much larger sample size. We also compare measurements of the parasitic scattering from pinhole collimation with that from focusing cylindrical quartz mirrors, and a focusing refractive optic, to stress the importance of signal-to-noise as the true measure of performance for SANS instruments.

  1. Novel Materials for Collimators at LHC and its Upgrades

    CERN Document Server

    AUTHOR|(CDS)2108536; Dallocchio, Alessandro; Garlasche, Marco; Gentini, Luca; Gradassi, Paolo; Guinchard, Michael; Redaelli, Stefano; Rossi, Adriana; Sacristan De Frutos, Oscar; Carra, Federico; Quaranta, Elena

    2015-01-01

    Collimators for last-generation particle accelerators like the LHC, must be designed to withstand the close interaction with intense and energetic particle beams, safely operating over an extended range of temperatures in harsh environments, while minimizing the perturbing effects, such as instabilities induced by RF impedance, on the circulating beam. The choice of materials for collimator active components is of paramount importance to meet these requirements, which are to become even more demanding with the increase of machine performances expected in future upgrades, such as the High Luminosity LHC (HL-LHC). Consequently, a farreaching R&D program has been launched to develop novel materials with excellent thermal shock resistance and high thermal and electrical conductivity, replacing or complementing materials used for present collimators. Molybdenum Carbide - Graphite and Copper-Diamond composites have been so far identified as the most promising materials. The manufacturing methods, properties and...

  2. At Bright Band Inside Victoria Crater

    Science.gov (United States)

    2007-01-01

    A layer of light-toned rock exposed inside Victoria Crater in the Meridiani Planum region of Mars appears to mark where the surface was at the time, many millions of years ago, when an impact excavated the crater. NASA's Mars Exploration Rover Opportunity drove to this bright band as the science team's first destination for the rover during investigations inside the crater. Opportunity's left front hazard-identification camera took this image just after the rover finished a drive of 2.25 meters (7 feet, 5 inches) during the rover's 1,305th Martian day, or sol, (Sept. 25, 2007). The rocks beneath the rover and its extended robotic arm are part of the bright band. Victoria Crater has a scalloped shape of alternating alcoves and promontories around the crater's circumference. Opportunity descended into the crater two weeks earlier, within an alcove called 'Duck Bay.' Counterclockwise around the rim, just to the right of the arm in this image, is a promontory called 'Cabo Frio.'

  3. Optical nanostructures in 2D for wide-diameter and broadband beam collimation.

    Science.gov (United States)

    Clark, James; Anguita, José V; Chen, Ying; Silva, S Ravi P

    2016-01-01

    Eliminating curved refracting lensing components used in conventional projection, imaging and sensing optical assemblies, is critical to enable compactness and miniaturisation of optical devices. A suitable means is replacing refracting lenses with two-dimensional optical media in flat-slab form, to achieve an equivalent optical result. One approach, which has been the focus of intense research, uses a Veselago lens which features a negative-index metamaterial. However, practical implementations rely on resonance techniques, thus broadband operation at optical frequencies imposes significant technical challenges that have been difficult to overcome. Here, we demonstrate a highly-collimated, broadband, wide-diameter beam from a compact source in flat-slab form, based on light collimation using nanomaterials ordered in patterns and embedded into flexible polymers. These provide a highly anisotropic absorption coefficient due to patterns created by vertical carbon nanotube structures grown on glass, and the anisotropic electrical conductivity of the nanotubes. We show this nanostructure strongly absorbs unwanted off-axis light rays, whilst transmitting the desired on-axis rays, to achieve the required optical effect over broadband, from visible to short-infrared, thus circumventing some technical limitations of negative-index metamaterials. We further show a low substrate-temperature system for nanotube growth, allowing direct implementation into heat-sensitive large-area devices. PMID:26732851

  4. Optical nanostructures in 2D for wide-diameter and broadband beam collimation

    Science.gov (United States)

    Clark, James; Anguita, José V.; Chen, Ying; Silva, S. Ravi P.

    2016-01-01

    Eliminating curved refracting lensing components used in conventional projection, imaging and sensing optical assemblies, is critical to enable compactness and miniaturisation of optical devices. A suitable means is replacing refracting lenses with two-dimensional optical media in flat-slab form, to achieve an equivalent optical result. One approach, which has been the focus of intense research, uses a Veselago lens which features a negative-index metamaterial. However, practical implementations rely on resonance techniques, thus broadband operation at optical frequencies imposes significant technical challenges that have been difficult to overcome. Here, we demonstrate a highly-collimated, broadband, wide-diameter beam from a compact source in flat-slab form, based on light collimation using nanomaterials ordered in patterns and embedded into flexible polymers. These provide a highly anisotropic absorption coefficient due to patterns created by vertical carbon nanotube structures grown on glass, and the anisotropic electrical conductivity of the nanotubes. We show this nanostructure strongly absorbs unwanted off-axis light rays, whilst transmitting the desired on-axis rays, to achieve the required optical effect over broadband, from visible to short-infrared, thus circumventing some technical limitations of negative-index metamaterials. We further show a low substrate-temperature system for nanotube growth, allowing direct implementation into heat-sensitive large-area devices.

  5. Collimation of the $e^{+}e^{-}$ annihilation event

    CERN Document Server

    Kimura, K

    1997-01-01

    The collimation $C$ of a hadronic event in the e^+e^- annihilation is defined as the average of $\\cos\\theta$, $C=$, where $\\theta$ is the angle of each hadron measured from the thrust axis, and the average is over all the hadrons produced in an event. It is an infrared-stable event-shape parameter. $1-\\bar C$, the difference between the unity and the average collimation at a given energy, is proportional to the anomalous dimension of the hadron multiplicity at the leading order in MLLA. Its next-to-leading order corrections are calculated.

  6. Jet Collimation by Small-Scale Magnetic Fields

    OpenAIRE

    Li, Li-Xin

    2001-01-01

    A popular model for jet collimation is associated with the presence of a large-scale and predominantly toroidal magnetic field originating from the central engine (a star, a black hole, or an accretion disk). Besides the problem of how such a large-scale magnetic field is generated, in this model the jet suffers from the fatal long-wave mode kink magnetohydrodynamic instability. In this paper we explore an alternative model: jet collimation by small-scale magnetic fields. These magnetic field...

  7. Simulation of the low-frequency collimator impedance

    CERN Document Server

    Kroyer, T

    2008-01-01

    The low-frequency transverse collimator impedance constitutes a major part of the LHC impedance budget. In this paper numerical simulations for frequencies below 1 MHz using a commercial package are presented. From the 3D field solution of the two-wire simulations the transverse impedance is directly calculated. After a cross-check with theory for rotationally symmetric structures a geometry with two jaws and an LHC graphite collimator is examined. Furthermore, a simple physics picture that explains the principal characteristics of the impedance at high and low frequencies is given.

  8. Automated Detection and Tracking of Solar Magnetic Bright Points

    CERN Document Server

    Crockett, P J; Mathioudakis, M; Keenan, F P

    2009-01-01

    Magnetic Bright Points (MBPs) in the internetwork are among the smallest objects in the solar photosphere and appear bright against the ambient environment. An algorithm is presented that can be used for the automated detection of the MBPs in the spatial and temporal domains. The algorithm works by mapping the lanes through intensity thresholding. A compass search, combined with a study of the intensity gradient across the detected objects, allows the disentanglement of MBPs from bright pixels within the granules. Object growing is implemented to account for any pixels that might have been removed when mapping the lanes. The images are stabilized by locating long-lived objects that may have been missed due to variable light levels and seeing quality. Tests of the algorithm employing data taken with the Swedish Solar Telescope (SST), reveal that ~90% of MBPs within a 75"x 75" field of view are detected.

  9. Bright Stuff on Ceres = Sulfates and Carbonates on CI Chondrites

    Science.gov (United States)

    Zolensky, Michael; Chan, Queenie H. S.; Gounelle, Matthieu; Fries, Marc

    2016-01-01

    Recent reports of the DAWN spacecraft's observations of the surface of Ceres indicate that there are bright areas, which can be explained by large amounts of the Mg sulfate hexahydrate (MgSO4•6(H2O)), although the identification appears tenuous. There are preliminary indications that water is being evolved from these bright areas, and some have inferred that these might be sites of contemporary hydro-volcanism. A heat source for such modern activity is not obvious, given the small size of Ceres, lack of any tidal forces from nearby giant planets, probable age and presumed bulk composition. We contend that observations of chondritic materials in the lab shed light on the nature of the bright spots on Ceres

  10. Measuring Anthropogenic Sky Glow Using a Natural Sky Brightness Model

    Science.gov (United States)

    Duriscoe, Dan M.

    2013-11-01

    Anthropogenic sky glow (a result of light pollution) combines with the natural background brightness of the night sky when viewed by an observer on the earth's surface. In order to measure the anthropogenic component accurately, the natural component must be identified and subtracted. A model of the moonless natural sky brightness in the V-band was constructed from existing data on the Zodiacal Light, an airglow model based on the van Rhijn function, and a model of integrated starlight (including diffuse galactic light) constructed from images made with the same equipment used for sky brightness observations. The model also incorporates effective extinction by the atmosphere and is improved at high zenith angles (>80°) by the addition of atmospheric diffuse light. The model may be projected onto local horizon coordinates for a given observation at a resolution of 0.05° over the hemisphere of the sky, allowing it to be accurately registered with data images obtained from any site. Zodiacal Light and integrated starlight models compare favorably with observations from remote dark sky sites, matching within ± 8 nL over 95% of the sky. The natural airglow may be only approximately modeled, errors of up to ± 25 nL are seen when the airglow is rapidly changing or has considerable character (banding); ± 8 nL precision may be expected under favorable conditions. When subtracted from all-sky brightness data images, the model significantly improves estimates of sky glow from anthropogenic sources, especially at sites that experience slight to moderate light pollution.

  11. Perceiving the Intensity of Light

    Science.gov (United States)

    Purves, Dale; Williams, S. Mark; Nundy, Surajit; Lotto, R. Beau

    2004-01-01

    The relationship between luminance (i.e., the photometric intensity of light) and its perception (i.e., sensations of lightness or brightness) has long been a puzzle. In addition to the mystery of why these perceptual qualities do not scale with luminance in any simple way, "illusions" such as simultaneous brightness contrast, Mach bands,…

  12. Advances in pinhole and multi-pinhole collimators for single photon emission computed tomography imaging.

    Science.gov (United States)

    Islamian, Jalil Pirayesh; Azazrm, AhmadReza; Mahmoudian, Babak; Gharapapagh, Esmail

    2015-01-01

    The collimator in single photon emission computed tomography (SPECT), is an important part of the imaging chain. One of the most important collimators that used in research, preclinical study, small animal, and organ imaging is the pinhole collimator. Pinhole collimator can improve the tradeoff between sensitivity and resolution in comparison with conventional parallel-hole collimator and facilities diagnosis. However, a major problem with pinhole collimator is a small field of view (FOV). Multi-pinhole collimator has been investigated in order to increase the sensitivity and FOV with a preserved spatial resolution. The geometry of pinhole and multi-pinhole collimators is a critical factor in the image quality and plays a key role in SPECT imaging. The issue of the material and geometry for pinhole and multi-pinhole collimators have been a controversial and much disputed subject within the field of SPECT imaging. On the other hand, recent developments in collimator optimization have heightened the need for appropriate reconstruction algorithms for pinhole SPECT imaging. Therefore, iterative reconstruction algorithms were introduced to minimize the undesirable effect on image quality. Current researches have focused on geometry and configuration of pinhole and multi-pinhole collimation rather than reconstruction algorithm. The lofthole and multi-lofthole collimator are samples of novel designs. The purpose of this paper is to provide a review on recent researches in the pinhole and multi-pinhole collimators for SPECT imaging. PMID:25709537

  13. New paradigm of detection: 10x14 URA patterned sensitive collimator

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tae Woong; Lee, Won Ho [Korea University, Seoul (Korea, Republic of)

    2012-05-15

    A common method of radiation imaging is mechanical collimation which shows good performance at the low radiation energy and the other is electronic collimation whose angular resolution is better at higher radiation energy. Many researchers have developed equipment combining two kinds of collimation methods showing good performance in wide range of radiation energy. However, most of them used passive collimators made of high Z material such as Pb or W and the scattered radiations in the mechanical collimator were regarded as noise events and discarded. In this research, the mechanical collimator itself was replaced by a sensitive detector consisting of a URA patterned scintillator. Since our sensitive collimation could be used as both mechanical can electronic collimation simultaneously, the scattered radiation in the mechanical collimation, which was discarded in the conventional gamma cameras, was recovered as an effective event for the electronic collimation (Compton imaging) to reconstruct the radiation image. As a result, the detection efficiency and image quality can be dramatically increased. The sensitive collimation using both mechanical and electronic collimation, and hence it can cover very broad energy range (several keV {approx} MeV) of the incident radiation. We developed sensitive collimation using 10 x 14 URA patterned scintillator, whose spatial resolution was improved in comparison of the previous prototype

  14. Helmholtz bright and boundary solitons

    Energy Technology Data Exchange (ETDEWEB)

    Christian, J M [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); McDonald, G S [Joule Physics Laboratory, School of Computing, Science and Engineering, Institute for Materials Research, University of Salford, Salford M5 4WT (United Kingdom); Chamorro-Posada, P [Departmento de TeorIa de la Senal y Comunicaciones e IngenierIa Telematica, Universidad de Valladolid, ETSI Telecomunicacion, Campus Miguel Delibes s/n, 47011 Valladolid (Spain)

    2007-02-16

    We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic nonlinear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently derived Helmholtz bright solitons, for this type of polynomial nonlinearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterparts.

  15. GPM Intercalibrated Radiometer Brightness Temperatures

    Science.gov (United States)

    Stocker, Erich Franz; Chou, Joyce

    2013-04-01

    One of the keys to consistent precipitation retrieval from passive microwave radiometer measurements (whether imagers or sounders) is accurate, long-term consistent brightness temperature retrievals. This becomes doubly important when there measurements are taken from radiometers on multiple platforms, from multiple agencies, with many different purposes. The Global Precipitation Measurement (GPM) mission addresses this issue directly with the production of intercalibrated brightness temperatures from all the partner satellites contributing to the GPM mission. These intercalibrated brightness temperatures are given the product designation: 1C within GPM. This paper will describe the GPM approach to intercalibration 1C products. The intercalibration and creation of the products uses a 5-step methodology: comparison of the partner standard products (either Tb or Ta) with the GPM reference standard; determination of adjustments that should be made to each product to create consistent brightness temperatures; re-orbitization of all orbits (in non-realtime) to be in the standard GPM south-south orbit; application of the adjustments to the partner provide 1B(or 1A) products; production of 1C products in HDF5 using a "standard" logical format for any radiometer regardless of its 1B format. This paper describes each of these steps and provides the background for them. It discusses in some detail the current 1C logical format and why this format facilitates use by downstream product algorithms and end-users. Most importantly it provides the analysis approach established by the GPM inter-calibration working group in establishing the adjustments to be made at the 1C level. Finally, using DMSP F16-18, it provides examples of the 1C products and discusses the adjustments that are made.

  16. Bright solitons from defocusing nonlinearities

    OpenAIRE

    Borovkova, Olga V.; Kartashov, Yaroslav; Torner Sabata, Lluís; Malomed, Boris A.

    2011-01-01

    We report that defocusing cubic media with spatially inhomogeneous nonlinearity, whose strength increases rapidly enough toward the periphery, can support stable bright localized modes. Such nonlinearity landscapes give rise to a variety of stable solitons in all three dimensions, including one-dimensional fundamental and multihump states, two-dimensional vortex solitons with arbitrarily high topological charges, and fundamental solitons in three dimensions. Solitons maintain their coherence ...

  17. Night sky brightness at San Pedro Martir Observatory

    CERN Document Server

    Plauchu-Frayn, I; Colorado, E; Herrera, J; Cordova, A; Cesena, U; Avila, F

    2016-01-01

    We present optical UBVRI zenith night sky brightness measurements collected on eighteen nights during 2013--2016 and SQM measurements obtained daily over twenty months during 2014--2016 at the Observatorio Astronomico Nacional on the Sierra San Pedro Martir (OAN-SPM) in Mexico. The UBVRI data is based upon CCD images obtained with the 0.84m and 2.12m telescopes, while the SQM data is obtained with a high-sensitivity, low-cost photometer. The typical moonless night sky brightness at zenith averaged over the whole period is U = 22.68, B = 23.10, V = 21.84, R = 21.04, I = 19.36, and SQM = 21.88 mag/square arcsec, once corrected for zodiacal light. We find no seasonal variation of the night sky brightness measured with the SQM. The typical night sky brightness values found at OAN-SPM are similar to those reported for other astronomical dark sites at a similar phase of the solar cycle. We find a trend of decreasing night sky brightness with decreasing solar activity during period of the observations. This trend im...

  18. Built-in hyperspectral camera for smartphone in visible, near-infrared and middle-infrared lights region (second report): sensitivity improvement of Fourier-spectroscopic imaging to detect diffuse reflection lights from internal human tissues for healthcare sensors

    Science.gov (United States)

    Kawashima, Natsumi; Hosono, Satsuki; Ishimaru, Ichiro

    2016-05-01

    We proposed the snapshot-type Fourier spectroscopic imaging for smartphone that was mentioned in 1st. report in this conference. For spectroscopic components analysis, such as non-invasive blood glucose sensors, the diffuse reflection lights from internal human skins are very weak for conventional hyperspectral cameras, such as AOTF (Acousto-Optic Tunable Filter) type. Furthermore, it is well known that the spectral absorption of mid-infrared lights or Raman spectroscopy especially in long wavelength region is effective to distinguish specific biomedical components quantitatively, such as glucose concentration. But the main issue was that photon energies of middle infrared lights and light intensities of Raman scattering are extremely weak. For improving sensitivity of our spectroscopic imager, the wide-field-stop & beam-expansion method was proposed. Our line spectroscopic imager introduced a single slit for field stop on the conjugate objective plane. Obviously to increase detected light intensities, the wider slit width of the field stop makes light intensities higher, regardless of deterioration of spatial resolutions. Because our method is based on wavefront-division interferometry, it becomes problems that the wider width of single slit makes the diffraction angle narrower. This means that the narrower diameter of collimated objective beams deteriorates visibilities of interferograms. By installing the relative inclined phaseshifter onto optical Fourier transform plane of infinity corrected optical systems, the collimated half flux of objective beams derived from single-bright points on objective surface penetrate through the wedge prism and the cuboid glass respectively. These two beams interfere each other and form the infererogram as spatial fringe patterns. Thus, we installed concave-cylindrical lens between the wider slit and objective lens as a beam expander. We successfully obtained the spectroscopic characters of hemoglobin from reflected lights from

  19. THE COLLIMATION AND ENERGETICS OF THE BRIGHTEST SWIFT GAMMA-RAY BURSTS

    International Nuclear Information System (INIS)

    Long-duration gamma-ray bursts (GRBs) are widely believed to be highly collimated explosions (bipolar conical outflows with half-opening angle θ∼ 10-100). As a result of this beaming factor, the true energy release from a GRB is usually several orders of magnitude smaller than the observed isotropic value. Measuring this opening angle, typically inferred from an achromatic steepening in the afterglow light curve (a 'jet' break), has proven exceedingly difficult in the Swift era. Here, we undertake a study of five of the brightest (in terms of the isotropic prompt γ-ray energy release, Eγ,iso) GRBs in the Swift era to search for jet breaks and hence constrain the collimation-corrected energy release. We present multi-wavelength (radio through X-ray) observations of GRBs 050820A, 060418, and 080319B, and construct afterglow models to extract the opening angle and beaming-corrected energy release for all three events. Together with results from previous analyses of GRBs 050904 and 070125, we find evidence for an achromatic jet break in all five events, strongly supporting the canonical picture of GRBs as collimated explosions. The most natural explanation for the lack of observed jet breaks from most Swift GRBs is therefore selection effects. However, the opening angles for the events in our sample are larger than would be expected if all GRBs had a canonical energy release of ∼1051 erg. The total energy release we measure for the 'hyper-energetic' (Etot ∼> 1052 erg) events in our sample is large enough to start challenging models with a magnetar as the compact central remnant.

  20. THE INNERMOST COLLIMATION STRUCTURE OF THE M87 JET DOWN TO ∼10 SCHWARZSCHILD RADII

    Energy Technology Data Exchange (ETDEWEB)

    Hada, Kazuhiro; Giroletti, Marcello; Giovannini, Gabriele [INAF Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna (Italy); Kino, Motoki; Doi, Akihiro [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara 252-5210 (Japan); Nagai, Hiroshi; Honma, Mareki; Hagiwara, Yoshiaki; Kawaguchi, Noriyuki [National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo 181-8588 (Japan)

    2013-09-20

    We investigated the detailed inner jet structure of M87 using Very Long Baseline Array data at 2, 5, 8.4, 15, 23.8, 43, and 86 GHz, especially focusing on the multi-frequency properties of the radio core at the jet base. First, we measured the size of the core region transverse to the jet axis, defined as W{sub c}, at each frequency ν, and found a relation between W{sub c} and ν: W{sub c}(ν)∝ν{sup –0.71±0.05}. Then, by combining W{sub c}(ν) and the frequency dependence of the core position r{sub c}(ν), which was obtained in our previous study, we constructed a collimation profile of the innermost jet W{sub c}(r) down to ∼10 Schwarzschild radii (R{sub s}) from the central black hole. We found that W{sub c}(r) smoothly connects with the width profile of the outer edge-brightened, parabolic jet and then follows a similar radial dependence down to several tens of R{sub s}. Closer to the black hole, the measured radial profile suggests a possible change in the jet collimation shape from the outer parabolic one, where the jet shape tends to become more radially oriented. This result could be related to a magnetic collimation process or/and interactions with surrounding materials at the jet base. The present results shed light on the importance of higher-sensitivity/resolution imaging studies of M87 at 86, 43, and 22 GHz; these studies should be examined more rigorously.

  1. High brightness semiconductor lasers with reduced filamentation

    DEFF Research Database (Denmark)

    McInerney, John; O'Brien, Peter.; Skovgaard, Peter M. W.;

    1999-01-01

    High brightness semiconductor lasers have applications in spectroscopy, fiber lasers, manufacturing and materials processing, medicine and free space communication or energy transfer. The main difficulty associated with high brightness is that, because of COD, high power requires a large aperture...

  2. Creating a collimated ultrasound beam in highly attenuating fluids.

    Science.gov (United States)

    Raeymaekers, Bart; Pantea, Cristian; Sinha, Dipen N

    2012-04-01

    We have devised a method, based on a parametric array concept, to create a low-frequency (300-500 kHz) collimated ultrasound beam in fluids highly attenuating to sound. This collimated beam serves as the basis for designing an ultrasound visualization system that can be used in the oil exploration industry for down-hole imaging in drilling fluids. We present the results of two different approaches to generating a collimated beam in three types of highly attenuating drilling mud. In the first approach, the drilling mud itself was used as a nonlinear mixing medium to create a parametric array. However, the short absorption length in mud limits the mixing length and, consequently, the resulting beam is weak and broad. In the second improved approach, the beam generation process was confined to a separate "frequency mixing tube" that contained an acoustically non-linear, low attenuation medium (e.g., water) that allowed establishing a usable parametric array in the mixing tube. A low-frequency collimated beam was thus created prior to its propagation into the drilling fluid. Using the latter technique, the penetration depth of the low frequency ultrasound beam in the drilling fluid was significantly extended. We also present measurements of acoustic nonlinearity in various types of drilling mud. PMID:22204917

  3. Implementation of intensity modulation with dynamic multileaf collimation

    Energy Technology Data Exchange (ETDEWEB)

    Wong, J.W.; Yu, C.; Jaffray, D. [William Beaumont Hospital, Royal Oak, MI (United States)

    1995-12-01

    The computer-controlled multileaf collimator (MLC) marks one of the most important advances in radiation therapy. The device efficiently replaces manual blocking to shape fields and can be used to modulate beam intensity. The results of a research programme at William Beaumont Hospital, aimed at bringing dynamic intensity modulation into clinical use, are discussed.

  4. Collimation of energetic neutrinos and muons inside EAS cores

    Directory of Open Access Journals (Sweden)

    Cherif Talai Mohammed

    2013-06-01

    Full Text Available High-energy muon and neutrino components are simulated inside cores of EAS generated by primary protons and heavy nuclei of energies 1014-1020 eV. The collimation of muons and neutrinos inside the core is compared with present penetrating beams generated by accelerators.

  5. The practical Pomeron for high energy proton collimation

    Science.gov (United States)

    Appleby, R. B.; Barlow, R. J.; Molson, J. G.; Serluca, M.; Toader, A.

    2016-10-01

    We present a model which describes proton scattering data from ISR to Tevatron energies, and which can be applied to collimation in high energy accelerators, such as the LHC and FCC. Collimators remove beam halo particles, so that they do not impinge on vulnerable regions of the machine, such as the superconducting magnets and the experimental areas. In simulating the effect of the collimator jaws it is crucial to model the scattering of protons at small momentum transfer t, as these protons can subsequently survive several turns of the ring before being lost. At high energies these soft processes are well described by Pomeron exchange models. We study the behaviour of elastic and single-diffractive dissociation cross sections over a wide range of energy, and show that the model can be used as a global description of the wide variety of high energy elastic and diffractive data presently available. In particular it models low mass diffraction dissociation, where a rich resonance structure is present, and thus predicts the differential and integrated cross sections in the kinematical range appropriate to the LHC. We incorporate the physics of this model into the beam tracking code MERLIN and use it to simulate the resulting loss maps of the beam halo lost in the collimators in the LHC.

  6. The collimation of magnetic jets by disk winds

    CERN Document Server

    Globus, Noemie

    2016-01-01

    The collimation of a Poynting-flux dominated jet by a wind emanating from the surface of an accretion flow is computed using a semi-analytic model. The injection of the disk wind is treated as a boundary condition in the equatorial plane, and its evolution is followed by invoking a prescribed geometry of streamlines. Solutions are obtained for a wide range of disk wind parameters. It is found that jet collimation generally occurs when the total wind power exceeds about ten percents of the jet power. For moderate wind powers we find gradual collimation. For strong winds we find rapid collimation followed by focusing of the jet, after which it remains narrow over many Alfv\\'en crossing times before becoming conical. We estimate that in the later case the jet's magnetic field may be dissipated by the current-driven kink instability over a distance of a few hundreds gravitational radii. We apply the model to M87 and show that the observed parabolic shape of the radio jet within the Bondi radius can be reproduced ...

  7. The collimation of magnetic jets by disc winds

    Science.gov (United States)

    Globus, N.; Levinson, A.

    2016-09-01

    The collimation of a Poynting-flux dominated jet by a wind emanating from the surface of an accretion flow is computed using a semi-analytic model. The injection of the disc wind is treated as a boundary condition in the equatorial plane, and its evolution is followed by invoking a prescribed geometry of streamlines. Solutions are obtained for a wide range of disc wind parameters. It is found that jet collimation generally occurs when the total wind power exceeds about 10 percents of the jet power. For moderate wind powers, we find gradual collimation. For strong winds, we find rapid collimation followed by focusing of the jet, after which it remains narrow over many Alfvén crossing times before becoming conical. We estimate that in the later case, the jet's magnetic field may be dissipated by the current-driven kink instability over a distance of a few hundreds gravitational radii. We apply the model to M87 and show that the observed parabolic shape of the radio jet within the Bondi radius can be reproduced provided that the wind injection zone extends to several hundreds gravitational radii, and that its total power is about one-third of the jet power. The radio spectrum can be produced by synchrotron radiation of relativistically hot, thermal electrons in the sheath flow surrounding the inner jet.

  8. Geometric Beam Coupling Impedance of LHC Secondary Collimators

    CERN Document Server

    Frasciello, O; Zobov, M; Grudiev, A; Mounet, N; Salvant, B

    2014-01-01

    The High Luminosity LHC project is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the beam intensity increase. In order to keep under control beam instabilities and to avoid excessive power losses a careful design of new vacuum chamber components and an improvement of the present LHC impedance model are required. Collimators are the main impedance contributors. Measurements with beam have revealed that the betatron coherent tune shifts were by about a factor of 2 higher with respect to the theoretical predictions based on the current model. Up to now the resistive wall impedance has been considered as the major impedance contribution for collimators. By carefully simulating their geometric impedance we show that for the graphite collimators with half-gaps higher than 10 mm the geometric impedance exceeds the resistive wall one. In turn, for the tungsten collimators the geometric impedance dominates for all used gap values. Hence, i...

  9. Slow axis collimation lens with variable curvature radius for semiconductor laser bars

    Science.gov (United States)

    Xiong, Ling-Ling; Cai, Lei; Zheng, Yan-Fang; Liu, Hui; Zhang, Pu; Nie, Zhi-Qiang; Liu, Xing-Sheng

    2016-03-01

    Based on Snell's law and the constant phase in the front of optical field, a design method of the slow axis collimation lens with variable curvature radius is proposed for semiconductor laser bars. Variable radius of the collimator is designed by the transmission angle, and it is demonstrated that the collimator has good beam collimation ability by material with low refractive index. Resorting to the design thought of finite element method, the surface of the collimator has been divided, and it is feasible to be fabricated. This method is applied as an example in collimation of a 976 nm semiconductor laser bar. 6 mrad divergence angle of collimated beam at slow axis is realized by the designed collimation lens with refraction index of 1.51.

  10. Observation of strong leakage reduction in crystal assisted collimation of the SPS beam

    Science.gov (United States)

    Scandale, W.; Arduini, G.; Butcher, M.; Cerutti, F.; Garattini, M.; Gilardoni, S.; Lechner, A.; Losito, R.; Masi, A.; Mereghetti, A.; Metral, E.; Mirarchi, D.; Montesano, S.; Redaelli, S.; Rossi, R.; Schoofs, P.; Smirnov, G.; Bagli, E.; Bandiera, L.; Baricordi, S.; Dalpiaz, P.; Germogli, G.; Guidi, V.; Mazzolari, A.; Vincenzi, D.; Claps, G.; Dabagov, S.; Hampai, D.; Murtas, F.; Cavoto, G.; Iacoangeli, F.; Ludovici, L.; Santacesaria, R.; Valente, P.; Galluccio, F.; Afonin, A. G.; Chesnokov, Yu. A.; Durum, A. A.; Maisheev, V. A.; Sandomirskiy, Yu. E.; Yanovich, A. A.; Kovalenko, A. D.; Taratin, A. M.; Gavrikov, Yu. A.; Ivanov, Yu. M.; Lapina, L. P.; Fulcher, J.; Hall, G.; Pesaresi, M.; Raymond, M.

    2015-09-01

    In ideal two-stage collimation systems, the secondary collimator-absorber should have its length sufficient to exclude practically the exit of halo particles with large impact parameters. In the UA9 experiments on the crystal assisted collimation of the SPS beam a 60 cm long tungsten bar is used as a secondary collimator-absorber which is insufficient for the full absorption of the halo protons. Multi-turn simulation studies of the collimation allowed to select the position for the beam loss monitor downstream the collimation area where the contribution of particles deflected by the crystal in channeling regime but emerging from the secondary collimator-absorber is considerably reduced. This allowed observation of a strong leakage reduction of halo protons from the SPS beam collimation area, thereby approaching the case with an ideal absorber.

  11. Automatic Computer Algorithms for Beam-based Setup of the LHC Collimators

    CERN Document Server

    Valentino, G; Assmann, R W; Bruce, R; Redaelli, S; Salvachua, B; Wollmann, D

    2012-01-01

    Beam-based setup of the LHC collimators is necessary to establish the beam centers and beam sizes at the collimator locations and determine the operational settings during various stages of the LHC machine cycle.

  12. High-brightness rf linear accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Jameson, R.A.

    1986-01-01

    The issue of high brightness and its ramifications in linacs driven by radio-frequency fields is discussed. A history of the RF linacs is reviewed briefly. Some current applications are then examined that are driving progress in RF linacs. The physics affecting the brightness of RF linacs is then discussed, followed by the economic feasibility of higher brightness machines. (LEW)

  13. Execution of mantle field with multileaf collimator: A simple approach

    Directory of Open Access Journals (Sweden)

    Prabhakar Ramachandran

    2008-01-01

    Full Text Available Background: Until very recently mantle field radiotherapy remained the gold standard for the treatment of favorable early-stage Hodgkin′s lymphoma. The classic mantle includes all the major lymph nodes above the diaphragm and extends from the inferior portion of the mandible to the level of the insertion of the diaphragm. Aims: To describe a simple technique that has been devised to treat the mantle field with the help of multileaf collimator and using computed tomography (CT-based treatment planning. Materials and Methods: CT scan was performed with the patient in the supine position and the datasets were transferred to the Eclipse™ treatment planning system. Elekta Precise™ linear accelerator equipped with 40 pairs of multileaf collimator (MLC was used for the execution of the mantle field. The MLC′s shapes were designed to take the shape of the conventional customized blocks used for treatment of mantle field. The anterior mantle field was divided into three separate MLC segments with the collimator kept at 0°. The first MLC segment was shaped to cover the neck, clavicular regions, and mediastinum. The second and the third MLC segments covered the right and left axilla, respectively. The posterior fields were opposed to the anterior subfields in a similar fashion. The dose was prescribed at the midplane, using reference points. Results and Conclusion: The technique described in this study is very simple, easy to implement, and avoids unnecessary delay in the execution of the mantle field. The mantle field can be easily shaped with the multileaf collimators, without any collimator rotation.

  14. Dimensionality constraints of light induced rotation

    CERN Document Server

    Oroszi, László; Galajda, Péter; Kelemen, Lóránd; Mathesz, Anna; Vicsek, Tamás; Vizsnyiczai, Gaszton; Ormos, Pál

    2015-01-01

    We have studied the conditions of rotation induced by collimated light carrying no angular momentum. Objects of different shapes and optical properties were examined in the nontrivial case where the rotation axis is perpendicular to the direction of light propagation. This geometry offers important advantages for application as it fundamentally broadens the possible practical arrangements to be realised. We found that collimated light cannot drive permanent rotation of 2D or prism-like 3D objects (i.e. fixed cross-sectional profile along the rotation axis) in the case of fully reflective or fully transparent materials. Based on both geometrical optics simulations and theoretical analysis, we derived a general condition for rotation induced by collimated light carrying no angular momentum valid for any arrangement: Permanent rotation is not possible if the scattering interaction is two-dimensional and lossless. In contrast, light induced rotation can be sustained if partial absorption is present or the object ...

  15. Design and performance of a small-animal imaging system using synthetic collimation

    OpenAIRE

    Havelin, R J; Miller, B W; Barrett, H. H.; Furenlid, L.R.; Murphy, J M; Foley, M J

    2013-01-01

    This work outlines the design and construction of a single-photon emission computed tomography (SPECT) imaging system based on the concept of synthetic collimation. A focused multi-pinhole collimator is constructed using rapid-prototyping and casting techniques. The collimator projects the centre of the field of view (FOV) through forty-six pinholes when the detector is adjacent to the collimator, with the number reducing towards the edge of the FOV. The detector is then moved further from th...

  16. Adaptive Lighting

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... the investigations of lighting scenarios carried out in two test installations: White Cube and White Box. The test installations are discussed as large-scale experiential instruments. In these test installations we examine what could potentially occur when light using LED technology is integrated and...

  17. Variable Circular Collimator in Robotic Radiosurgery: A Time-Efficient Alternative to a Mini-Multileaf Collimator?

    NARCIS (Netherlands)

    Van de Water, S.; Hoogeman, M.S.; Breedveld, S.; Nuyttens, J.J.M.E.; Schaart, D.R.; Heijmen, B.J.M.

    2011-01-01

    urpose Compared with many small circular beams used in CyberKnife treatments, beam’s eye view-shaped fields are generally more time-efficient for dose delivery. However, beam’s eye view-shaping devices, such as a mini-multileaf collimator (mMLC), are not presently available for CyberKnife, although

  18. Improved robustness of the LHC collimation system by operating with a jaw-beam angle

    CERN Document Server

    Lari, L; Rossi, A; Cauchi, M; Faus-Golfe, A

    2012-01-01

    The robustness of the Phase I collimation system could be improved playing with the angular orientation of each single jaw. A preliminary study on the asymmetric misalignment of the collimator jaws, scanning through different jaw angles and varying beam sizes and energy, have been carried out, aiming at minimizing the energy deposited on metallic collimators, following an asynchronous dump.

  19. Development of the ICOSIM Program and Application to Magnetised Collimators in the LHC

    CERN Document Server

    Holden, N

    2008-01-01

    This note has two parts. The first part provides documentation for the ICOSIM program used to simulate collimation of Ion beams. The second part contains results of a preliminary study of the effectiveness of magnetised collimators as a means to increase collimation efficiency for lead ion beams in the LHC.

  20. Evaluation of parathyroid imaging methods with {sup 99m}Tc-MIBI. The comparison of planar images obtained using a pinhole collimator and a parallel-hole collimator

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Hirofumi; Iwasaki, Ryuichiro; Hashimoto, Jun; Nakamura, Kayoko; Kunieda, Etsuo; Sanmiya, Toshikazu; Kubo, Atsushi [Keio Univ., Tokyo (Japan). School of Medicine; Ogawa, Koichi; Inagaki, Kazutoshi

    1999-07-01

    Parathyroid scintigraphy with {sup 99m}Tc-MIBI was performed using two kinds of collimators, namely, a pinhole one and a parallel-hole one, to evaluate which one was more suitable for the detection of hyperfunctioning parathyroid lesions. In the studies using {sup 99m}Tc source, the pinhole collimator showed better efficiency and spatial resolution in the distance where the parathyroid scan are actually performed. In the phantom study, the nodular activities modeling parathyroid lesions were visualized better on the images obtained using the pinhole collimator. In clinical studies for 30 patients suspicious of hyperparathyroidism, hyperfunctioning parathyroid nodules were better detected when the pinhole collimator was used. In conclusion, the pinhole collimator was thought to be more suitable for parathyroid scintigraphy with {sup 99m}Tc-MIBI than the parallel-hole collimator. (author)

  1. The HH 24 Jet Complex: Collimated and Colliding Jets from a Newborn Multiple Stellar System

    Science.gov (United States)

    Reipurth, Bo

    2013-10-01

    The HH 24 complex constitutes the richest concentration of collimated bright Herbig-Haro jets known, and they originate from a small grouping of newborn binary and multiple systems. At least 6 jets are identified in deep groundbased optical interference images, and a similar number of sources in infrared images. We propose to do the first HST study of this complex, using H-alpha and [SII] filters. HST 0.05" to 0.1" angular resolution {20 to 40 AU at d 400 pc} is needed to resolve the shocks and their post-shock cooling layers for comparison with advanced numerical modeling. Our emphasis here is to explore outflows from a multiple system of newborn stars. Many of the jets show clear evidence of wiggling. The theory of jet motion from binary systems coupled with disk precession is now understood, and we will interpret the jet wiggles in this framework. Additionally, two of the HH 24 jets are showing evidence for a collision, a unique situation not seen anywhere else, and HST resolution is needed for comparison with gas-dynamic studies of jet-jet collisions. Two of the HH 24 jets are bright in the infrared [FeII] 1.644 line. In this line the main jet can be traced all the way to the source, which is the most important region for understanding the effects of binarity on the jet structure. We also apply for a second-epoch [SII] image in Cycle 23. This allows us, in addition to deriving the bulk motion, to determine such processes as expansion of the jet beam, sideways ejection in a working surface, turbulent and chaotic motions, and the effect of instabilities.

  2. High brightness beams and applications

    International Nuclear Information System (INIS)

    This paper describes the present research on attaining intense bright electron beams. Thermionic systems are briefly covered. Recent and past results from the photoinjector programs are given. The performance advantages and difficulties presently faced by researchers using photoinjectors is discussed. The progress that has been made in photocathode materials, both in lifetime and quantum efficiency, is covered. Finally, a discussion of emittance measurements of photoinjector systems and how the measurement is complicated by the non-thermal nature of the electron beam is presented

  3. Freeform étendue-preserving optics for light and color mixing

    Science.gov (United States)

    Sorgato, Simone; Mohedano, Rubén.; Chaves, Julio; Cvetkovic, Aleksandra; Hernández, Maikel; Benítez, Pablo; Miñano, Juan C.; Thienpont, Hugo; Duerr, Fabian

    2015-09-01

    Today's SSL illumination market shows a clear trend towards high flux packages with higher efficiency and higher CRI, realized by means of multiple color chips and phosphors. Such light sources require the optics to provide both near- and far-field color mixing. This design problem is particularly challenging for collimated luminaries, since traditional diffusers cannot be employed without enlarging the exit aperture and reducing brightness (so increasing étendue). Furthermore, diffusers compromise the light output ratio (efficiency) of the lamps to which they are applied. A solution, based on Köhler integration, consisting of a spherical cap comprising spherical microlenses on both its interior and exterior sides was presented in 2012. When placed on top of an inhomogeneous multichip Lambertian LED, this so-called Shell-Mixer creates a homogeneous (both spatially and angularly) virtual source, also Lambertian, where the images of the chips merge. The virtual source is located at the same position with essentially the same size of the original source. The diameter of this optics was 3 times that of the chip-array footprint. In this work, we present a new version of the Shell-Mixer, based on the Edge Ray Principle, where neither the overall shape of the cap nor the surfaces of the lenses are constrained to spheres or rotational Cartesian ovals. This new Shell- Mixer is freeform, only twice as large as the original chip-array and equals the original model in terms of brightness, color uniformity and efficiency.

  4. An energy-optimized collimator design for a CZT-based SPECT camera

    Science.gov (United States)

    Weng, Fenghua; Bagchi, Srijeeta; Zan, Yunlong; Huang, Qiu; Seo, Youngho

    2016-01-01

    In single photon emission computed tomography, it is a challenging task to maintain reasonable performance using only one specific collimator for radiotracers over a broad spectrum of diagnostic photon energies, since photon scatter and penetration in a collimator differ with the photon energy. Frequent collimator exchanges are inevitable in daily clinical SPECT imaging, which hinders throughput while subjecting the camera to operational errors and damage. Our objective is to design a collimator, which is independent of the photon energy, performs reasonably well for commonly used radiotracers with low- to medium-energy levels of gamma emissions. Using the Geant4 simulation toolkit, we simulated and evaluated a parallel-hole collimator mounted to a CZT detector. With the pixel-geometry-matching collimation, the pitch of the collimator hole was fixed to match the pixel size of the CZT detector throughout this work. Four variables, hole shape, hole length, hole radius/width and the source-to-collimator distance were carefully studied. Scatter and penetration of the collimator, sensitivity and spatial resolution of the system were assessed for four radionuclides including 57Co, 99mTc, 123I and 111In, with respect to the aforementioned four variables. An optimal collimator was then decided upon such that it maximized the total relative sensitivity (TRS) for the four considered radionuclides while other performance parameters, such as scatter, penetration and spatial resolution, were benchmarked to prevalent commercial scanners and collimators. Digital phantom studies were also performed to validate the system with the optimal square-hole collimator (23 mm hole length, 1.28 mm hole width, and 0.32 mm septal thickness) in terms of contrast, contrast-to-noise ratio and recovery ratio. This study demonstrates promise of our proposed energy-optimized collimator to be used in a CZT-based gamma camera, with comparable or even better imaging performance versus commercial

  5. Diffusion filter eliminates fringe effects of coherent laser light source

    Science.gov (United States)

    Olsasky, M. J.

    1970-01-01

    Diffusion filter comprised of small particles in colloidal suspension reduces the coherence of a laser beam used as a photographic light source. Interference patterns which obscure details in photographic film are eliminated, the intensity and collimation are moderately affected.

  6. Scientific investigations with the data base HEAO-1 scanning modulator collimator

    Science.gov (United States)

    Schwartz, Daniel A.

    1992-01-01

    The hardware specification for the Scanning Modulation Collimator (MC) experiment on HEAO-1 was to measure positions of bright (greater than 10(exp -11) ergs/cm(exp 2)s), hard (1 to 15 keV) x-ray sources to 5-10 arcsec, and to measure their size and structure in three energy bands down to 10 arcsec resolution. The scientific purpose of this specification was to enable the identification of these x-ray sources with optical and radio objects in order to elucidate the x-ray emission mechanism and the nature of the candidate astronomical system. The experiment was an outstanding success. Hardware systems functioned perfectly although loss of one (out of eight) proportional counters degraded our sensitivity by about 10 percent. Our aspect solution of 7 arcsec precision, allowed us to achieve statistic-limited location precision for all but the strongest sources. We vigorously pursued a strategy of determining the scientific importance of each identification, and of publishing each scientific result as it came along.

  7. The triple-shell structure and collimated outflows of the planetary nebula NGC 6891

    CERN Document Server

    Guerrero, M; Manchado, A; Vázquez, R A

    1999-01-01

    Narrow-band H$\\alpha$ and [N {\\sc ii}] images and high-dispersion spatially-resolved echelle spectroscopy of the planetary nebula NGC 6891 are presented. These observations show a great wealth of structures. The bright central nebula is surrounded by an attached shell and a detached outer halo. Both the inner and intermediate shells can be described as ellipsoids with similar major to minor axial ratios, but different spatial orientations. The kinematical ages of the intermediate shell and halo are 4,800 and 28,000 years, respectively. The inter-shell time lapse is in good agreement with the evolutionary inter-pulse time lapse. A highly collimated outflow is observed to protrude from the tips of the major axis of the inner nebula and impact on the outer edge of the intermediate shell. Kinematics and excitation of this outflow provide conclusive evidence that it is deflected during the interaction with the outer edge of the intermediate shell. At the same time, both the kinematics and the morphology of the int...

  8. Extreme Properties Of GRB061007: A Highly Energetic Or A Highly Collimated Burst?

    CERN Document Server

    Schady, P; Page, M J; Vetere, L; Pandey, S B; Wang, X Y; Cummings, J; Zhang, B; Zane, S; Breeveld, A; Burrows, D N; Gronwall, N G C; Hunsberger, S; Markwardt, C; Mason, K O; Mészáros, P; Oates, S R; Pagani, C; Poole, T S; Roming, P W A; Smith, P J; Vanden Berk, D E

    2006-01-01

    GRB061007 is the brightest gamma-ray burst (GRB) to be detected by Swift and is accompanied by an exceptionally luminous afterglow that had a V-band magnitude <11.1 at 80s after the prompt emission. From the start of the Swift observations the afterglow decayed as a power law with a slope of \\alpha_X=1.66+/-0.01 in the X-ray and \\alpha_{opt}=1.64+/-0.01 in the UV/optical, up to the point that it was no longer detected above background in the optical or X-ray bands. The brightness of this GRB and the similarity in the decay rate of the X-ray, optical and gamma-ray emission from 100s after the trigger distinguish this burst from others and present a challenge to the fireball model. The lack of a cooling or jet break in the afterglow up to \\~10^5s constrains any model that can produce the large luminosity observed in GRB061007, which we found to require either an excessively large kinetic energy or highly collimated outflow. Analysis of the multi-wavelength spectral and high-resolution temporal data taken wit...

  9. Extreme Properties Of GRB061007: A Highly Energetic OR Highly Collimated Burst?

    CERN Document Server

    Schady, P; Cummings, J; Page, M J; Pandey, S B; Wang, X Y; Vetere, L; Zhang, B; Zane, S; Breeveld, A; Burrows, D N; Gehrels, N; Gronwall, C; Ger, S H; Markwardt, C; Mason, K O; Mészáros, P; Oates, S R; Pagani, C; Poole, T S; Roming, P W A; Smith, P; Vanden Berk, D E

    2006-01-01

    GRB 061007 is the most energetic gamma-ray burst (GRB) to be detected by \\swift and is accompanied by an exceptionally luminous afterglow that had a $V$-band magnitude $< 11.1$ at 80 s after the prompt emission. From the start of the \\swift observations the afterglow decayed as a power law with a slope of $\\alpha_X=1.66\\pm 0.01$ in the X-ray and $\\alpha_{opt}=1.64\\pm 0.01$ in the UV/optical, up to the point that it was no longer detected above background in the optical or X-ray bands. The brightness of this GRB and the similarity in the decay rate of the X-ray, optical and $\\gamma$-ray emission from 100 s after the trigger, distinguish this burst from others and present a challenge to the fireball model. The lack of a cooling or jet break in the afterglow up to $\\sim 10^{5}$ s constrains any model that can produce the large luminosity observed in GRB 061007, which we found to require either an excessively large kinetic energy or highly collimated outflow. The multi-wavelength spectral and high-resolution t...

  10. Collimator Improvements 2011 and Upgrade 2012: What Do We Plan?

    CERN Document Server

    Redaelli, S

    2011-01-01

    The LHC collimation system has provided an outstanding performance during the first year of high-intensity beam operation. The complete Phase I system was commissioned and delivered routinely a cleaning performance close to the nominal exceptions with relaxed collimator settings. On the other hand, the first commissioning experience has also provided first indications of system limitations alongside of hints for possible improvements. In particular, the expected performance limitations from losses in the cold dispersion suppressors (DSs) at either side of the warm cleaning insertions have been confirmed. While improvements of the system will already be implemented during the 2010 shutdown, the major performance limitation from the DS require a change of the machine layout that will be addresses in the 2012 long shutdown. In this papers, the proposed improvements of the system are presented. The expected gains and the implication of the proposed changes on the system re-commissioning are discussed.

  11. Self-collimated slow sound in sonic crystals

    International Nuclear Information System (INIS)

    Self-collimated slow-sound propagation in a two-dimensional rectangular sonic crystal composed of elliptical scatterers in air is numerically demonstrated. The group velocity at the centre and the edges of the fourth acoustic band is reduced to 45 m s-1 and 30 m s-1, corresponding to 1/8 and 1/12 of the speed of sound in air, respectively. Elimination of omni-directional reflections encountered in linear waveguides and the reduction of group-velocity dispersion at the mid-band frequencies lead to preservation of pulse shape and amplitude upon traversal of the sonic crystal. Wave transmission is increased from approximately -20 to -2.5 dB, with almost an order of magnitude enhancement, via injector layers optimized through a pattern search algorithm. Self-collimating performance of the system is not degraded under oblique incidence, except for pulse broadening due to increased effective source width.

  12. Ocular vergence measurement in projected and collimated simulator displays.

    Science.gov (United States)

    Morahan, P; Meehan, J W; Patterson, J; Hughes, P K

    1998-09-01

    The purpose of this study was to investigate electrooculography (EOG) as a measurement of ocular vergence in both collimated and projected simulator environments. The task required participants to shift their gaze between a central fixation point and a target appearing at one of three eccentricities. EOG was effective in recording ocular vergence. The EOG results were similar between collimated and projected displays, except for differences in vergence changes during lateral movement of the eyes, and ocular excursions downward elicited a greater EOG response than the reverse upward movement. The computer-based technique of recording vergence was found to produce measurable traces from a majority of participants. The technique has potential for further development as a tool for measuring ocular vergence in virtual environments where methods that require the wearing of head-mounted apparatus to track ocular structures (e.g., the pupil), which cannot be worn at the same time as a flight or flight-simulator helmet, are unsuitable.

  13. Simulator for beam-based LHC collimator alignment

    Science.gov (United States)

    Valentino, Gianluca; Aßmann, Ralph; Redaelli, Stefano; Sammut, Nicholas

    2014-02-01

    In the CERN Large Hadron Collider, collimators need to be set up to form a multistage hierarchy to ensure efficient multiturn cleaning of halo particles. Automatic algorithms were introduced during the first run to reduce the beam time required for beam-based setup, improve the alignment accuracy, and reduce the risk of human errors. Simulating the alignment procedure would allow for off-line tests of alignment policies and algorithms. A simulator was developed based on a diffusion beam model to generate the characteristic beam loss signal spike and decay produced when a collimator jaw touches the beam, which is observed in a beam loss monitor (BLM). Empirical models derived from the available measurement data are used to simulate the steady-state beam loss and crosstalk between multiple BLMs. The simulator design is presented, together with simulation results and comparison to measurement data.

  14. Adaptive Lighting

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...... distributed differently into an architectural body. We also examine what might occur when light is dynamic and able to change colour, intensity and direction, and when it is adaptive and can be brought into interaction with its surroundings. In short, what happens to an architectural space when artificial...

  15. Calculation of the collimated bremsstrahlung flux from thin radiators

    International Nuclear Information System (INIS)

    A method is outlined for calculating the absolute flux of a bremsstrahlung beam created by passing an electron beam through thin radiators. Multiple scattering of the electron beam in the radiator and collimation of the bremsstrahlung flux are considered in this calculation. Separate measurements determine that this calculations has an absolute accuracy of 2.8% for an endpoint energy range from 120 to 360 MeV for a total radiator thickness of less than 0.012 radiation lengths. (orig.)

  16. Plasma tubes becoming collimated as a result of magnetohydrodynamic pumping

    OpenAIRE

    Yun, Gunsu S.; Bellan, Paul M.

    2010-01-01

    Collimated magnetized plasma structures are commonly observed on galactic, stellar, and laboratory scales. The Caltech plasma gun produces magnetically driven plasma jets bearing a striking resemblance to astrophysical jets and solar coronal loops by imposing boundary conditions analogous to those plasmas. This paper presents experimental observations of gun-produced plasma jets that support a previously proposed magnetohydrodynamic (MHD) pumping model [ P. M. Bellan, Phys. Plasmas 10, 1999 (...

  17. Neutron collimator design of neutron radiography based on the BNCT facility

    CERN Document Server

    Yang, XP; Li, YG; Peng, D; Lu, J; Zhang, GL; Zhao, H; Zhang, AW; Li, CY; Liu, WJ; Hu, T; Lv, JG

    2013-01-01

    For the research of CCD neutron radiography, a neutron collimator was designed based on the exit of thermal neutron of the Boron Neutron Capture Therapy (BNCT) reactor. Based on the Geant4 simulations, the preliminary choice of the size of the collimator was determined. The materials were selected according to the literature data. Then, a collimator was constructed and tested on site. The results of experiment and simulation show that the thermal neutron flux at the end of theneutron collimator is greater than 10^6 n/cm^2/s, the maximum collimation ratio (L/D) is 58, the Cd-ratio(Mn) is 160 and the diameter of collimator end is 10 cm. This neutron collimator is considered to be applicable for neutron radiography.

  18. Neutron collimator design of neutron radiography based on the BNCT facility

    International Nuclear Information System (INIS)

    For the research of CCD neutron radiography, a neutron collimator was designed based on the exit of thermal neutron of the Boron Neutron Capture Therapy (BNCT) reactor. Based on the Geant4 simulations, the preliminary choice of the size of the collimator was determined. The materials were selected according to the literature data. Then, a collimator was constructed and tested on site. The results of experiment and simulation show that the thermal neutron flux at the end of the neutron collimator is greater than 1.0×106 n/cm2/s, the maximum collimation ratio (L/D) is 58, the Cd-ratio(Mn) is 160 and the diameter of collimator end is 10 cm. This neutron collimator is considered to be applicable for neutron radiography. (authors)

  19. LHC Collimators with Embedded Beam Position Monitors: a New Adbanced Mechanical Design

    CERN Document Server

    Dallocchio, A; Boccard, C; Carra, F; Gasior, M; Gentini, L; Timmins, M

    2011-01-01

    The LHC collimation system, ensuring both functions of beam cleaning and machine protection, is potentially submitted to high-energy beam impacts. Currently the collimators setup is performed by monitoring beam losses generated by the collimator jaws when approaching the particle beam. This procedure is applied to all LHC collimators (almost one hundred), taking several hours, and needs to be repeated if beam settings change significantly. Furthermore, during the beam-based alignment, the LHC tertiary collimators are potentially exposed to abnormal losses entailing possible damage to their tungsten jaws. To improve the efficiency of the machine operation and better control the particle beam a new advanced design embedding Beam Position Monitors (BPM) into the movable collimator jaws has been developed. This paper describes the mechanical design of various types of future collimators with embedded BPMs. Experimental measurements performed on a simplified functional prototype installed in the CERN SPS showed th...

  20. Mechanical Engineering and Design of Novel Collimators for HL-LHC

    CERN Document Server

    Carra, F; Dallocchio, A; Gentini, L; Gradassi, P; Maitrejean, G; Manousos, A; Mariani, N; Mounet, N; Quaranta, E; Redaelli, S; Vlachoudis, V

    2014-01-01

    In view of High Luminosity LHC (HL-LHC) upgrades, collimator materials may become a limit to the machine performance: the high RF impedance of Carbon-Carbon composites used for primary and secondary collimators can lead to beam instabilities, while the Tungsten alloy adopted in tertiary collimators exhibits low robustness in case of beam-induced accidents. An R&D program has been pursued to develop new materials overcoming such limitations. Molybdenum-Graphite, in addition to its outstanding thermal conductivity, can be coated with pure molybdenum, reducing collimator impedance by a factor of 10. A new secondary collimator is being designed around this novel composite. New high-melting materials are also proposed to improve the robustness of tertiary collimators. New collimators will also be equipped with BPMs, significantly enhancing the alignment speed and the beta-star reach. This implies additional constraints of space, as well as detailed static and fatigue calculations on cables and connectors. This...

  1. Algorithms for optimal sequencing of dynamic multileaf collimators

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, Srijit [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Sahni, Sartaj [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States); Palta, Jatinder [Department of Radiation Oncology, University of Florida, Gainesville, FL (United States); Ranka, Sanjay [Department of Computer and Information Science and Engineering, University of Florida, Gainesville, FL (United States)

    2004-01-07

    Dynamic multileaf collimator (DMLC) intensity modulated radiation therapy (IMRT) is used to deliver intensity modulated beams using a multileaf collimator (MLC), with the leaves in motion. DMLC-IMRT requires the conversion of a radiation intensity map into a leaf sequence file that controls the movement of the MLC while the beam is on. It is imperative that the intensity map delivered using the leaf sequence file be as close as possible to the intensity map generated by the dose optimization algorithm, while satisfying hardware constraints of the delivery system. Optimization of the leaf-sequencing algorithm has been the subject of several recent investigations. In this work, we present a systematic study of the optimization of leaf-sequencing algorithms for dynamic multileaf collimator beam delivery and provide rigorous mathematical proofs of optimized leaf sequence settings in terms of monitor unit (MU) efficiency under the most common leaf movement constraints that include leaf interdigitation constraint. Our analytical analysis shows that leaf sequencing based on unidirectional movement of the MLC leaves is as MU efficient as bi-directional movement of the MLC leaves.

  2. Evaluation of the penumbras of a Philips multileaf collimator

    Energy Technology Data Exchange (ETDEWEB)

    Lafay, F.; Malet, C.; Mombard, C.; Ginestet, C. [Centre de Lutte Contre le Cancer Leon-Berard, 69 - Lyon (France); Blondel, E. [Isotec, Saint-Quentin (France); Desfarges, Y.; Dupin, G. [Philips Medical System, Lyon (France)

    1995-12-01

    Since January 1995, a Philips SL20 linear accelerator which is connected to a multileaf collimator has been used. Computer-controlled multileaf collimators open up the opportunity to practice conformal radiotherapy. Its aim is to adjust as well as possible the Planning Target Volume (PTV) to the effective treated volume with an homogeneous dose distribution in the PTV, and to protect healthy tissues and delicate organs. This is possible by means of a multileaf collimator by increasing the number of complex fields with different incidences during a same session. Moreover, the Beam`s Eye View function of the three-dimensional treatment planning system allows to define the shape of complex fields. For rectangular fields, the penumbra is defined by the distance between the 80% and 20% isodoses relative to the beam axis. In addition, the distances between, respectively, the 95% and 50% isodoses, the 90% and 50% isodoses, the 50% and 20% isodoses relative to the beam axis have been analysed. Different penumbras were evaluated. The result of this work will enable to adjust the reference isodose to the PTV either by integrating this result into dosimetry software, or by taking it into account for drawing the PTV.

  3. Independent checks of linear accelerators equipped with multileaf collimators

    International Nuclear Information System (INIS)

    National Radiation Protection Institute (NRPI) provides independent checks of therapeutic equipment as a part of state supervision. In the end of 2003, the audit was broaden for linear accelerators equipped with multileaf collimators (MLC). NRPI provides TLD postal audits and on-site independent checks. This contribution describes tests for multileaf collimators and intensity modulated radiation therapy (IMRT) technique that are accomplished within the independent on-site check of linear accelerators. The character and type of tests that are necessary to pursue for multileaf collimator depends on application technique. There are three basic application of the MLC. The first we call 'static MLC' and it serves for replacing conventional blocking or for adjusting the field shape to match the beam's-eye view projection of a planning target volume during an arc rotation of the x-ray beam. This procedure is called conformal radiotherapy. The most advanced technique with MLC is intensity modulated radiation therapy. The dose can be delivered to the patient with IMRT in various different ways: dynamic MLC, segmented MLC and IMRT arc therapy. Independent audits represent an important instrument of quality assurance. Methodology for independent check of static MLC was successfully verified on two types of accelerators: Varian and Elekta. Results from pilot measurements with dynamic MLC imply that the methodology is applicable for Varian accelerators. In the future, the experience with other types of linear accelerators will contribute to renovation, modification, and broaden independent checks methodology. (authors)

  4. The first "water fountain" collimated outflow in a planetary nebula

    CERN Document Server

    Gomez, J F; Bendjoya, Ph; Rizzo, J R; Miranda, L F; Green, J A; Uscanga, L; Garcia-Garcia, E; Lagadec, E; Guerrero, M A; Ramos-Larios, G

    2014-01-01

    "Water fountains" (WFs) are evolved objects showing high-velocity, collimated jets traced by water maser emission. Most of them are in the post-Asymptotic Giant Branch and they may represent one of the first manifestations of collimated mass loss in evolved stars. We present water maser, carbon monoxide, and mid-infrared spectroscopic data (obtained with the Australia Telescope Compact Array, Herschel Space Observatory, and the Very Large Telescope, respectively) toward IRAS 15103--5754, a possible planetary nebula (PN) with WF characteristics. Carbon monoxide observations show that IRAS 15103-5754 is an evolved object, while the mid-IR spectrum displays unambiguous [NeII] emission, indicating that photoionization has started and thus, its nature as a PN is confirmed. Water maser spectra show several components spreading over a large velocity range ~75 km/s and tracing a collimated jet. This indicates that the object is a WF, the first WF known that has already entered the PN phase. However, the spatial and k...

  5. The Practical Pomeron for High Energy Proton Collimation

    CERN Document Server

    Appleby, R B; Molson, J. G; Serluca, M.; Toader, A.

    2016-01-01

    We present a model which describes proton scattering data from ISR to Tevatron energies, and which can be applied to collimation n high energy accelerators, such as the LHC and FCC. Collimators remove beam halo particles, so that they do not impinge on vulnerable regions of the machine, such as the superconducting magnets and the experimental areas. In simulating the effect of the collimator jaws it is crucial to model the scattering of protons at small momentum transfer~$t$,as these protons can subsequently survive several turns of the ring before being lost. At high energies these soft processes are well described by Pomeron exchange models. We study the behaviour of elastic and single-diffractive dissociation cross sections over a wide range of energy, and show that the model can be used as a global description of the wide variety of high energy elastic and diffractive data presently available. In particular it models low mass diffraction dissociation, where a rich resonance structure is present, and thus ...

  6. Enhanced brightness from all solution processable biopolymer LED

    Science.gov (United States)

    Pradeep, C.; Namboothiry, M. A. G.; Vallabhan, C. P. G.; Radhakrishnan, P.; Nampoori, V. P. N.

    2015-08-01

    Biopolymer light emitting diodes were fabricated by using all solution processable polymers incorporating biomaterials such as deoxyribonucleic acid lipid complex as an electron blocking layer. Light emission is from a blend of fluorene based copolymers. The devices with electron blocking layer exhibited higher brightness and luminous efficiency. The increased luminance of the multilayer polymer LED is attributed to the contribution from DNA:CTMA as electron blocking layer and PFN, a derivative of polyfluorene, as electron injection layer. Our results show four fold increase in luminance values when DNA is used as electron blocking layer.

  7. Long distance fiber-optic displacement sensor based on fiber collimator

    Energy Technology Data Exchange (ETDEWEB)

    Shen Wei; Wu Xiaowei; Meng Hongyun; Zhang Guanbin; Huang Xuguang [Key Laboratory of Photonic Information Technology of Guangdong Higher Education Institutes, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)

    2010-12-15

    A simple fiber-optic displacement sensor based on reflective intensity modulated technology is demonstrated using a fiber collimator. The sensing range is over 30 cm, which is over 100 times that of the conventional fiber-optic displacement sensor based on the normal single-mode fiber. The measured data are fitted into linear equation very well and the values of R-square are more than 0.995. The sensitivity of the device achieves 0.426 dB/cm over the range of 5-30 cm. By applying the relative technique, the errors resulted from the fluctuation of light source and influences of environment are effectively eliminated, and the stability for wide range measurement can be improved. The simplicity of the design, high dynamic range, stability and the ease of the fabrication make it suitable for applications in industries.

  8. Extraordinary refraction and self-collimation properties of multilayer metallic-dielectric stratified structures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Liwei, E-mail: zlwhpu@hotmail.com [School of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China); Chen, Liang [School of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China); Zhang, Zhengren [School of Science, Chongqing Jiaotong University, Chongqing 400074 (China); Wang, Wusong [Guizhou Aerospace Institute of Measuring and Testing Technology, Guiyang 550009 (China); Zhao, Yuhuan; Song, Kechao; Kang, Chaoyang [School of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China)

    2015-01-15

    The extraordinary refraction with negative or zero refraction angle of the layered metamaterial consisting of alternating dielectric and plasmonic layers is theoretically studied. It is shown that the electromagnetic properties can be tuned by the filling factor, the permittivity of the dielectric layer and the plasma frequency of the metallic layer. At different frequency, the layered structures possess different refraction properties with positive, zero or negative refraction angle. By choosing appropriate parameters, positive-to-zero-to-negative-to positive refraction at the desired frequency can be realized. At the frequency with flat equal frequency contour, self-collimation and slow light properties are also found. Such properties can be used in the performance of negative refraction, subwavelength imaging and information propagation.

  9. LOR-interleaving image reconstruction for PET imaging with fractional-crystal collimation

    Science.gov (United States)

    Li, Yusheng; Matej, Samuel; Karp, Joel S.; Metzler, Scott D.

    2015-01-01

    Positron emission tomography (PET) has become an important modality in medical and molecular imaging. However, in most PET applications, the resolution is still mainly limited by the physical crystal sizes or the detector’s intrinsic spatial resolution. To achieve images with better spatial resolution in a central region of interest (ROI), we have previously proposed using collimation in PET scanners. The collimator is designed to partially mask detector crystals to detect lines of response (LORs) within fractional crystals. A sequence of collimator-encoded LORs is measured with different collimation configurations. This novel collimated scanner geometry makes the reconstruction problem challenging, as both detector and collimator effects need to be modeled to reconstruct high-resolution images from collimated LORs. In this paper, we present a LOR-interleaving (LORI) algorithm, which incorporates these effects and has the advantage of reusing existing reconstruction software, to reconstruct high-resolution images for PET with fractional-crystal collimation. We also develop a 3D ray-tracing model incorporating both the collimator and crystal penetration for simulations and reconstructions of the collimated PET. By registering the collimator-encoded LORs with the collimator configurations, high-resolution LORs are restored based on the modeled transfer matrices using the non-negative least-squares method and EM algorithm. The resolution-enhanced images are then reconstructed from the high-resolution LORs using the MLEM or OSEM algorithm. For validation, we applied the LORI method to a small-animal PET scanner, A-PET, with a specially designed collimator. We demonstrate through simulated reconstructions with a hot-rod phantom and MOBY phantom that the LORI reconstructions can substantially improve spatial resolution and quantification compared to the uncollimated reconstructions. The LORI algorithm is crucial to improve overall image quality of collimated PET, which

  10. Ultra-bright alkylated graphene quantum dots

    Science.gov (United States)

    Feng, Lan; Tang, Xing-Yan; Zhong, Yun-Xin; Liu, Yue-Wen; Song, Xue-Huan; Deng, Shun-Liu; Xie, Su-Yuan; Yan, Jia-Wei; Zheng, Lan-Sun

    2014-10-01

    Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The photocatalytic rate is ca. 5.9 times higher than that of pure P25, indicating that AGQDs could harness the visible spectrum of sunlight for energy conversion or environmental therapy.Highly efficient and stable photoluminescence (PL) are urgently desired for graphene quantum dots (GQDs) to facilitate their prospective applications as optical materials. Here, we report the facile and straightforward synthesis of alkylated graphene quantum dots (AGQDs) via the solvothermal reaction of propagatively alkylated graphene sheets (PAGenes). In contrast to most GQDs reported so far, the synthesized AGQDs process pH-independent and ultra-bright PL with a relative quantum yield of up to 65%. Structural and chemical composition characterization demonstrated that the synthesized AGQDs are nearly oxygen-defect-free with alkyl groups decorated on edges and basal plane, which may contribute to their greatly improved pH tolerance and high quantum efficiency. The photocatalytic performance of AGQDs-P25 nanocomposites was evaluated by the degradation of Rhodamine B under visible light. The

  11. SKY BRIGHTNESS AND TRANSPARENCY IN THE i-BAND AT DOME A, ANTARCTICA

    International Nuclear Information System (INIS)

    The i-band observing conditions at Dome A on the Antarctic plateau have been investigated using data acquired during 2008 with the Chinese Small Telescope Array. The sky brightness, variations in atmospheric transparency, cloud cover, and the presence of aurorae are obtained from these images. The median sky brightness of moonless clear nights is 20.5 mag arcsec-2 in the SDSS i band at the south celestial pole (which includes a contribution of about 0.06 mag from diffuse Galactic light). The median over all Moon phases in the Antarctic winter is about 19.8 mag arcsec-2. There were no thick clouds in 2008. We model contributions of the Sun and the Moon to the sky background to obtain the relationship between the sky brightness and transparency. Aurorae are identified by comparing the observed sky brightness to the sky brightness expected from this model. About 2% of the images are affected by relatively strong aurorae.

  12. Characterization of parallel-hole collimator using Monte Carlo Simulation

    International Nuclear Information System (INIS)

    Accuracy of in vivo activity quantification improves after the correction of penetrated and scattered photons. However, accurate assessment is not possible with physical experiment. We have used Monte Carlo Simulation to accurately assess the contribution of penetrated and scattered photons in the photopeak window. Simulations were performed with Simulation of Imaging Nuclear Detectors Monte Carlo Code. The simulations were set up in such a way that it provides geometric, penetration, and scatter components after each simulation and writes binary images to a data file. These components were analyzed graphically using Microsoft Excel (Microsoft Corporation, USA). Each binary image was imported in software (ImageJ) and logarithmic transformation was applied for visual assessment of image quality, plotting profile across the center of the images and calculating full width at half maximum (FWHM) in horizontal and vertical directions. The geometric, penetration, and scatter at 140 keV for low-energy general-purpose were 93.20%, 4.13%, 2.67% respectively. Similarly, geometric, penetration, and scatter at 140 keV for low-energy high-resolution (LEHR), medium-energy general-purpose (MEGP), and high-energy general-purpose (HEGP) collimator were (94.06%, 3.39%, 2.55%), (96.42%, 1.52%, 2.06%), and (96.70%, 1.45%, 1.85%), respectively. For MEGP collimator at 245 keV photon and for HEGP collimator at 364 keV were 89.10%, 7.08%, 3.82% and 67.78%, 18.63%, 13.59%, respectively. Low-energy general-purpose and LEHR collimator is best to image 140 keV photon. HEGP can be used for 245 keV and 364 keV; however, correction for penetration and scatter must be applied if one is interested to quantify the in vivo activity of energy 364 keV. Due to heavy penetration and scattering, 511 keV photons should not be imaged with HEGP collimator

  13. Automated Adaptive Brightness in Wireless Capsule Endoscopy Using Image Segmentation and Sigmoid Function.

    Science.gov (United States)

    Shrestha, Ravi; Mohammed, Shahed K; Hasan, Md Mehedi; Zhang, Xuechao; Wahid, Khan A

    2016-08-01

    Wireless capsule endoscopy (WCE) plays an important role in the diagnosis of gastrointestinal (GI) diseases by capturing images of human small intestine. Accurate diagnosis of endoscopic images depends heavily on the quality of captured images. Along with image and frame rate, brightness of the image is an important parameter that influences the image quality which leads to the design of an efficient illumination system. Such design involves the choice and placement of proper light source and its ability to illuminate GI surface with proper brightness. Light emitting diodes (LEDs) are normally used as sources where modulated pulses are used to control LED's brightness. In practice, instances like under- and over-illumination are very common in WCE, where the former provides dark images and the later provides bright images with high power consumption. In this paper, we propose a low-power and efficient illumination system that is based on an automated brightness algorithm. The scheme is adaptive in nature, i.e., the brightness level is controlled automatically in real-time while the images are being captured. The captured images are segmented into four equal regions and the brightness level of each region is calculated. Then an adaptive sigmoid function is used to find the optimized brightness level and accordingly a new value of duty cycle of the modulated pulse is generated to capture future images. The algorithm is fully implemented in a capsule prototype and tested with endoscopic images. Commercial capsules like Pillcam and Mirocam were also used in the experiment. The results show that the proposed algorithm works well in controlling the brightness level accordingly to the environmental condition, and as a result, good quality images are captured with an average of 40% brightness level that saves power consumption of the capsule. PMID:27333609

  14. 光环境功能区域划分及管理初探%Approach to the Zoning and Management forth Function of Light Environment

    Institute of Scientific and Technical Information of China (English)

    陈亢利

    2005-01-01

    Light pollution becomes more and more serious, butt he s tudyon this field is far from enough. ln this paper, light enyironment is defined as light-free area, dark area, intermediate sight area, and bright area In addition, it is marked with index walue by index system, which includes average brightness, brightness evenness, glare index, and background brightness.

  15. No functional magnetic resonance imaging evidence for brightness and color filling-in in early human visual cortex

    NARCIS (Netherlands)

    Cornelissen, FW; Wade, AR; Vladusich, T; Dougherty, RF; Wandell, BA

    2006-01-01

    The brightness and color of a surface depends on its contrast with nearby surfaces. For example, a gray surface can appear very light when surrounded by a black surface or dark when surrounded by a white surface. Some theories suggest that perceived surface brightness and color is represented explic

  16. Night sky brightness at sites from DMSP-OLS satellite measurements

    OpenAIRE

    Cinzano, Pierantonio; Elvidge, Cristopher D.

    2004-01-01

    We apply the sky brightness modelling technique introduced and developed by Roy Garstang to high-resolution DMSP-OLS satellite measurements of upward artificial light flux and to GTOPO30 digital elevation data in order to predict the brightness distribution of the night sky at a given site in the primary astronomical photometric bands for a range of atmospheric aerosol contents. This method, based on global data and accounting for elevation, Earth curvature and mountain screening, allows the ...

  17. Rapid-response, light-exposure control system

    Science.gov (United States)

    Kuehl, D. K.; Zwillenberg, M. L.

    1968-01-01

    Rapid-response electro-optical, light exposure control system, will maintain the light reaching a camera film or other light-sensitive detector at essentially constant level, despite wide variations in the brightness of the light source. The system permits detailed photographic or photoelectric recording of the phenomenon over a range of brightnesses.

  18. Extremely High Current, High-Brightness Energy Recovery Linac

    CERN Document Server

    Ben-Zvi, Ilan; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Burger, Al; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Favale, Anthony; Gassner, David M; Grimes, Jacob T; Hahn, Harald; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Lambiase, Robert; Litvinenko, Vladimir N; McIntyre, Gary; Meng, Wuzheng; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Segalov, Zvi; Smith, Kevin T; Todd, Alan M M; Warren-Funk, L; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Yip, Kin; Zaltsman, Alex; Zhao, Yongxiang

    2005-01-01

    Next generation ERL light-sources, high-energy electron coolers, high-power Free-Electron Lasers, powerful Compton X-ray sources and many other accelerators were made possible by the emerging technology of high-power, high-brightness electron beams. In order to get the anticipated performance level of ampere-class currents, many technological barriers are yet to be broken. BNL's Collider-Accelerator Department is pursuing some of these technologies for its electron cooling of RHIC application, as well as a possible future electron-hadron collider. We will describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun and an accelerator cavity capable of producing low emittance (about 1 micron rms normalized) one nano-Coulomb bunches at currents of the order of one ampere average.

  19. Microwave Brightness Temperature and Lunar Son Dielectric Property Retrieve

    Institute of Scientific and Technical Information of China (English)

    J. Wu; D.H. Li; A.T. Altyntsev; B.I. Lubyshev

    2005-01-01

    Among many scientific objectives of lunar exploration, investigations on lunar soil become more and more attractive to the scientists duo to the existence of abundant 3He and ilmenite in the lunar soil and their possible utilization. Although the soil composition determination on the lunar surface is available by visible light spectrometer, γ/X-ray spectrometer etc, the evaluations on the total reserves of 3He and ilmenite in the lunar deep and on the thickness of the lunar soil are still impossible so far. In this paper, the authors first give a rough analysis of the microwave brightness temperature images of the lunar disc observed using the NRAO 12 Meter Telescope and Siberian Solar Radio Telescope; then introduce our researches on the microwave dielectric properties of lunar soil simulators; finally, discuss some basic relations between the microwave brightness temperature and lunar soil properties.

  20. Radiation leakage dose from Elekta electron collimation system.

    Science.gov (United States)

    Pitcher, Garrett M; Hogstrom, Kenneth R; Carver, Robert L

    2016-01-01

    This study provided baseline data required for a greater project, whose objective was to design a new Elekta electron collimation system having significantly lighter electron applicators with equally low out-of field leakage dose. Specifically, off-axis dose profiles for the electron collimation system of our uniquely configured Elekta Infinity accelerator with the MLCi2 treatment head were measured and calculated for two primary purposes: 1) to evaluate and document the out-of-field leakage dose in the patient plane and 2) to validate the dose distributions calculated using a BEAMnrc Monte Carlo (MC) model for out-of-field dose profiles. Off-axis dose profiles were measured in a water phantom at 100 cm SSD for 1 and 2 cm depths along the in-plane, cross-plane, and both diagonal axes using a cylindrical ionization chamber with the 10 × 10 and 20 × 20 cm2 applicators and 7, 13, and 20 MeV beams. Dose distributions were calculated using a previously developed BEAMnrc MC model of the Elekta Infinity accelerator for the same beam energies and applicator sizes and compared with measurements. Measured results showed that the in-field beam flatness met our acceptance criteria (± 3% on major and ±4% on diagonal axes) and that out-of-field mean and maximum percent leakage doses in the patient plane met acceptance criteria as specified by the International Electrotechnical Commission (IEC). Cross-plane out-of-field dose profiles showed greater leakage dose than in-plane profiles, attributed to the curved edges of the upper X-ray jaws and multileaf collimator. Mean leakage doses increased with beam energy, being 0.93% and 0.85% of maximum central axis dose for the 10 × 10 and 20 × 20 cm2 applicators, respectively, at 20 MeV. MC calculations predicted the measured dose to within 0.1% in most profiles outside the radiation field; however, excluding model-ing of nontrimmer applicator components led to calculations exceeding measured data by as much as 0.2% for some regions

  1. Soliton fay identities: II. Bright soliton case

    International Nuclear Information System (INIS)

    We present a set of bilinear matrix identities that generalize the ones that have been used to construct the bright soliton solutions for various models. As an example of an application of these identities, we present a simple derivation of the N-bright soliton solutions for the Ablowitz–Ladik hierarchy. (paper)

  2. SURFACE PHOTOMETRY OF LOW SURFACE BRIGHTNESS GALAXIES

    NARCIS (Netherlands)

    DEBLOK, WJG; VANDERHULST, JM; BOTHUN, GD

    1995-01-01

    Low surface brightness (LSB) galaxies are galaxies dominated by an exponential disc whose central surface brightness is much fainter than the value of mu(B)(0) = 21.65 +/- 0.30 mag arcsec(-2) found by Freeman. In this paper we present broadband photometry of a sample of 21 late-type LSB galaxies. Th

  3. Brightness and darkness as perceptual dimensions

    NARCIS (Netherlands)

    Vladusich, T.; Lucassen, M.P.; Cornelissen, F.W.

    2007-01-01

    A common-sense assumption concerning visual perception states that brightness and darkness cannot coexist at a given spatial location. One corollary of this assumption is that achromatic colors, or perceived grey shades, are contained in a one-dimensional (1-D) space varying from bright to dark. The

  4. Incoherently coupled dark-bright photorefractive solitons

    Science.gov (United States)

    Chen, Zhigang; Segev, Mordechai; Coskun, Tamer H.; Christodoulides, Demetrios N.; Kivshar, Yuri S.; Afanasjev, Vsevolod V.

    1996-11-01

    We report the observation of incoherently coupled dark-bright spatial soliton pairs in a biased bulk photorefractive crystal. When such a pair is decoupled, the dark component evolves into a triplet structure, whereas the bright one decays into a self-defocusing beam.

  5. Brightness Alteration with Interweaving Contours

    Directory of Open Access Journals (Sweden)

    Sergio Roncato

    2012-12-01

    Full Text Available Chromatic induction is observed whenever the perceived colour of a target surface shifts towards the hue of a neighbouring surface. Some vivid manifestations may be seen in a white background where thin coloured lines have been drawn (assimilation or when lines of different colours are collinear (neon effect or adjacent (watercolour to each other. This study examines a particular colour induction that manifests in concomitance with an opposite effect of colour saturation (or anti-spread. The two phenomena can be observed when a repetitive pattern is drawn in which outline thin contours intercept wider contours or surfaces, colour spreading appear to fill the surface occupied by surfaces or thick lines whereas the background traversed by thin lines is seen as brighter or filled of a saturated white. These phenomena were first observed by Bozzi (1975 and Kanizsa (1979 in figural conditions that did not allow them to document their conjunction. Here we illustrate various manifestations of this twofold phenomenon and compare its effects with the known effects of brightness and colour induction. Some conjectures on the nature of these effects are discussed.

  6. High-Energy Compton Scattering Light Sources

    CERN Document Server

    Hartemann, Fred V; Barty, C; Crane, John; Gibson, David J; Hartouni, E P; Tremaine, Aaron M

    2005-01-01

    No monochromatic, high-brightness, tunable light sources currently exist above 100 keV. Important applications that would benefit from such new hard x-ray sources include: nuclear resonance fluorescence spectroscopy, time-resolved positron annihilation spectroscopy, and MeV flash radiography. The peak brightness of Compton scattering light sources is derived for head-on collisions and found to scale with the electron beam brightness and the drive laser pulse energy. This gamma 2

  7. Off-momentum collimation and cleaning in the energy ramp in the LHC

    CERN Document Server

    Quaranta, Elena; Giulini Castiglioni Agosteo, Stefano Luigi Maria

    This Master thesis work has been carried out at CERN in the framework of the LHC (Large Hadron Collider) Collimation project. The LHC is a two-beam proton collider, built to handle a stored energy of 360MJ for each beam. Since the energy deposition from particle losses could quench the superconducting magnets, a system of collimators has been installed in two cleaning insertions in the ring and in the experimental areas. The achievable LHC beam intensity is directly coupled to the beam loss rate and, consequently, to the cleaning eciency of the collimation system. This study analyses the collimation cleaning performance in dierent scenarios inside the accelerator. First, simulations are performed of the transverse losses in the LHC collimation system during the acceleration process. The results are compared with data taken during a dedicated session at the LHC machine. Simulations are also performed to predict the collimation eciency during future operation at higher energy. Furthermore, an investigation of t...

  8. A combined radial collimator and cooled beryllium filter for neutron scattering

    Science.gov (United States)

    Groitl, Felix; Rantsiou, Emmanouela; Bartkowiak, Marek; Filges, Uwe; Graf, Dieter; Niedermayer, Christof; Rüegg, Christian; Rønnow, Henrik M.

    2016-05-01

    A flexible, combined, radial collimator and beryllium (Be) filter have been designed and manufactured at the Paul Scherrer Institut (PSI), Switzerland. The Be is integrated in the radial collimator by placing thin Be slices between the collimator lamellas. The filter/collimator is mounted within a vacuum vessel and dry cooled. The flexible design allows for different degrees of collimation and for different Be lengths. Results of measurements carried out at the BOA beamline at PSI are presented. These experiments include rotation scans determining the focal full width half maximum (FWHM), transmission measurements, test of different collimator lamellas and performance tests of the cooling of the filter. This new combined device will be a crucial part of the CAMEA spectrometer at SINQ, PSI.

  9. First Design of a Proton Collimation System for 50 TeV FCC-hh

    CERN Document Server

    Fiascaris, Maria; Mirarchi, Daniele; Redaelli, Stefano

    2016-01-01

    We present studies aimed at defining a first conceptual solution for a collimation system for the hadron-hadron option for the Future Circular Collider (FCC-hh). The baseline collimation layout is based on the scaling of the present LHC collimation system to the FCC-hh energy. It currently includes a dedicated betatron cleaning insertion as well as collimators in the experimental insertions to protect the inner triplets. An aperture model for the FCC-hh is defined and the geometrical acceptance is calculated at top energy taking into account mechanical and optics imperfections. Based on these studies the collimator settings needed to protect the machine are defined. The performance of the collimation system is then assessed with particle tracking simulation tools assuming a perfect machine.

  10. Cerrobend collimation effect on electron beams; Efeito de colimacoes de cerrobend em feixes de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Furnari, Laura; Albino, Lucas D.; Ribeiro, Victor A.B.; Santos, Gabriela R., E-mail: laurafurnari@hotmail.com [Universidade de Sao Paulo (InRad/FM/USP), SP (Brazil). Faculdade de Medicina. Hospital das Clinicas. Instituto de Radiologia

    2012-12-15

    The aim of this work was to discuss about the cerrobend collimation effect on clinical electron beams. When a cerrobend collimation is used, both the percentage depth dose (PDD) and the absolute dose that is delivered to the patient changes. It was analyzed how those parameters change and it was evaluated in which cases a correction factor should be applied due to this collimation. It was founded that, when the smallest dimension of the collimation is smaller than the minimum radius to lateral scatter equilibrium, the collimation will change the PDD in such a way that it should take into account in the treatment planning. For one specific collimation usually applied in head and neck treatments, it was found that no correction factor is necessary. (author)

  11. Remote Estimation of Collimator Jaw Damages With Sounds Measurements During Beam Impacts

    CERN Document Server

    Deboy, D; Aberle, O; Carra, F; Cauchi, M; Lendaro, J; Masi, A; Redaelli, S

    2013-01-01

    Irregular hits of high-intensity LHC beams on collimators can lead to severe damage of the collimator jaws. The identification of damaged collimator jaws by observation of beam measurements is challenging: online loss measurements at the moment of the impacts can be tricky and degradation of the overall performance from single collimator damage can be difficult to measure. Visual inspections are excluded because collimator jaws are enclosed in vacuum tanks without windows. However, the sound generated during the beam impact can be used to give an estimate of the damage level. In 2012, high-intensity beam comparable to a full nominal LHC bunch at 7 TeV was shot on a tertiary type LHC collimator at the HiRadMat test facility at CERN. The paper presents results from sound recordings of this experiment.

  12. Plume collimation for laser ablation electrospray ionization mass spectrometry

    Science.gov (United States)

    Vertes, Akos; Stolee, Jessica A.

    2014-09-09

    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  13. Plume collimation for laser ablation electrospray ionization mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Vertes, Akos; Stolee, Jessica A.

    2016-06-07

    In various embodiments, a device may generally comprise a capillary having a first end and a second end; a laser to emit energy at a sample in the capillary to ablate the sample and generate an ablation plume in the capillary; an electrospray apparatus to generate an electrospray plume to intercept the ablation plume to produce ions; and a mass spectrometer having an ion transfer inlet to capture the ions. The ablation plume may comprise a collimated ablation plume. The device may comprise a flow cytometer. Methods of making and using the same are also described.

  14. Active collimators in experiments with exotic nuclear beams

    International Nuclear Information System (INIS)

    The active collimator method for experiments with exotic nuclear beams at the energies near Coulomb barrier of nuclear reactions is described. The apparatus consists of two blocks of microchannel plates (MCP) and thin strips of metallic foils (Au, Ag, Al), oriented along X and Y axes. MCPs register electron emission during penetration of exotic nuclei through these foils. It gives possibility to obtain information about particle trajectory and time mark of the event. The proposed technique provides the smallest amount of matter on the particle path (17 cm-2), high efficiency (ε ∼ 90% for every MCP), good time resolution for additional identification of radioactive nuclei using the time-of-flight method

  15. A condition on the spatial resolution of IR collimators for testing of thermal imaging systems

    Science.gov (United States)

    Chrzanowski, Krzysztof; Lee, Hee Chul; Wrona, Wieslaw

    2000-05-01

    A precise condition on the spatial resolution of the IR collimator for testing thermal imaging systems is presented. The condition can be used even if only the spatial resolution of the IR collimator and that of the system under test, measured using popular definitions, are known. It is shown that when the condition is fulfilled, the thermal image degradation caused by the IR collimator is negligible.

  16. Neutron collimator design of neutron radiography based on the BNCT facility

    OpenAIRE

    Yang, XP.; Yu, BX; Li, YG; Peng, D; Lu, J.; Zhang, GL.; Zhao, H.; Zhang, AW.; Li, CY.; Liu, WJ; Hu, T.; Lv, JG.

    2013-01-01

    For the research of CCD neutron radiography, a neutron collimator was designed based on the exit of thermal neutron of the Boron Neutron Capture Therapy (BNCT) reactor. Based on the Geant4 simulations, the preliminary choice of the size of the collimator was determined. The materials were selected according to the literature data. Then, a collimator was constructed and tested on site. The results of experiment and simulation show that the thermal neutron flux at the end of theneutron collimat...

  17. Dosimetric dependence on the collimator angle in prostate volumetric modulated arc therapy

    Directory of Open Access Journals (Sweden)

    Muhammad Isa

    2014-12-01

    Full Text Available Purpose: The purpose of this study is to investigate the dose-volume variations of planning target volume (PTV and organs-at-risk (OARs in prostate volumetric modulated arc therapy (VMAT when varying collimator angle. The collimator angle has the largest impact and is worth considering, so, its awareness is essential for a planner to produce an optimal prostate VMAT plan in a reasonable time frame. Methods: Single-arc VMAT plans at different collimator angles (0o, 15o, 30o, 45o, 60o, 75o and 90o were created systematically using a Harold heterogeneous pelvis phantom. The conformity index (CI, homogeneity index (HI, gradient index (GI, machine monitor units (MUs, dose-volume histogram and mean and maximum dose of the PTV were calculated and analyzed. On the other hand, the dose-volume histogram and mean and maximum doses of the OARs such as the bladder, rectum and femoral heads for different collimator angles were determined from the plans.Results: There was no significant difference, based on the planned dose-volume evaluation criteria, found in the VMAT optimizations for all studied collimator angles. A higher CI (0.53 and lower HI (0.064 were found in the 45o collimator angle. In addition, the 15o collimator angle provided a lower value of HI similar to the 45o collimator angle. Collimator angles of 75o and 90o were found to be good for rectum sparing, and collimator angles of 75o and 30o were found to be good for sparing of right and left femur, respectively. The PTV dose coverage for each plan was comparatively independent of the collimator angle. Conclusion: Our study indicates that the dosimetric results provide support and guidance to allow the clinical radiation physicists to make careful decisions in implementing suitable collimator angles to improve the PTV coverage and OARs sparing in prostate VMAT.

  18. Preliminary Comparison of the Response of LHC Tertiary Collimators to Proton and Ion Beam Impacts

    CERN Document Server

    Cauchi, M; Bertarelli, A; Carra, F; Cerutti, F; Lari, L; Mollicone, P; Sammut, N

    2013-01-01

    The CERN Large Hadron Collider is designed to bring into collision protons as well as heavy ions. Accidents involving impacts on collimators can happen for both species. The interaction of lead ions with matter differs to that of protons, thus making this scenario a new interesting case to study as it can result in different damage aspects on the collimator. This paper will present a preliminary comparison of the response of collimators to proton and ion beam impacts.

  19. Optimization of material in proton-therapy collimators with respect to neutron production

    OpenAIRE

    Gustafsson, Björn

    2009-01-01

    In this thesis, a study of neutron production properties for collimator materials is performed. Collimators are used in nuclear physics applications such as within the fields of nuclear energy and radiotherapy. The area of application is primarily reduction of static or unwanted radiation for detectors and treatment beams. This study focuses on a branch of radiotherapy called proton therapy where protons of high energies impinge on the collimator. Proton therapy has advantages compared to com...

  20. Bright Sparks of Our Future!

    Science.gov (United States)

    Riordan, Naoimh

    2016-04-01

    My name is Naoimh Riordan and I am the Vice Principal of Rockboro Primary School in Cork City, South of Ireland. I am a full time class primary teacher and I teach 4th class, my students are aged between 9-10 years. My passion for education has developed over the years and grown towards STEM (Science, Technology, Engineering and Mathematics) subjects. I believe these subjects are the way forward for our future. My passion and beliefs are driven by the unique after school programme that I have developed. It is titled "Sparks" coming from the term Bright Sparks. "Sparks" is an after school programme with a difference where the STEM subjects are concentrated on through lessons such as Science, Veterinary Science Computer Animation /Coding, Eco engineering, Robotics, Magical Maths, Chess and Creative Writing. All these subjects are taught through activity based learning and are one-hour long each week for a ten-week term. "Sparks" is fully inclusive and non-selective which gives all students of any level of ability an opportunity to engage into these subjects. "Sparks" is open to all primary students in County Cork. The "Sparks" after school programme is taught by tutors from the different Universities and Colleges in Cork City. It works very well because the tutor brings their knowledge, skills and specialised equipment from their respective universities and in turn the tutor gains invaluable teaching practise, can trial a pilot programme in a chosen STEM subject and gain an insight into what works in the physical classroom.

  1. Designers predict a bright future

    International Nuclear Information System (INIS)

    As power plant designers and builders, there is a bright future for the industry. The demand for electricity will continue to grow, and the need for new plants will increase accordingly. But companies that develop and supply these plants must adapt to new ways of doing business if they expect to see the dawn of this new age. Several factors will have a profound effect on the generation and use of electricity in future years. Instant communications now reach all corners of the globe, making people everywhere aspire to a higher standard of living. The economic surge needed to satisfy these appetites will, in turn, be fed by a network of suppliers who are themselves restructuring to serve global markets, unimpeded by past nationalistic barriers to trade. The strong correlation between economic progress and the growing demand for electricity is well recognized. A ready supply of affordable electricity is a necessary underpinning for any economic expansion. As economies advance and jobs increase, electric demand grows geometrically, fueled by an ever-improving quality of life. Coupled with increasing demand is the worldwide trend toward privatization of the generation industry. The reasons may vary in different parts of the world, but the effect is the same--companies are battling intensely for the right to build or purchase generating facilities. Those companies, like the industry they serve, are themselves in a period of transition. Once a closed, monopolistic group of owners in a predominantly services-based market, they are, thanks to competitive forces, being driven steadily toward a product-based structure

  2. Semi-automatic beam-based alignment algorithm for the LHC collimation system

    CERN Document Server

    Valentino, G; Redaelli, S; Sammut, N; Wollmann, D

    2011-01-01

    Full beam-based alignment of the LHC collimation system was a lengthy procedure as the collimators were setup manually. A yearly alignment campaign has been sufficient for now, although in future this may lead to a decrease in the cleaning efficiency if machine parameters such as the beam orbit drift over time. Automating the collimator setup procedure can allow for more frequent alignments, therefore reducing this risk. This paper describes the design and testing of a semi-automatic algorithmas a first step towards a fully automatic setup. Its implementation in the collimator control software and future plans are described.

  3. Optimization of the collimation system for CSNS/RCS with the robust conjugate direction search algorithm

    CERN Document Server

    Ji, H F; Huang, M Y; Xu, S Y; Wang, N; Wang, S

    2016-01-01

    The Robust Conjugate Direction Search (RCDS) method is used to optimize the collimation system for Rapid Cycling Synchrotron (RCS) of the Chinese Spallation Neutron Source (CSNS). The parameters of secondary collimators are optimized for a better performance of the collimation system. To improve the efficiency of the optimization, the Objective Ring Beam Injection and Tracking (ORBIT) parallel module combined with MATLAB parallel computing is used, which can run multiple ORBIT instances simultaneously. This study presents a way to figure out an optimal parameter combination of the secondary collimators for a machine model in preparation for CSNS/RCS commissioning.

  4. MERLIN Cleaning Studies with Advanced Collimator Materials for HL-LHC

    CERN Document Server

    Valloni, A.; Mereghetti, A.; Molson, J. G.; Appleby, R.; Bruce, R.; Quaranta, E.; Redaelli, S.

    2016-01-01

    The challenges of the High-Luminosity upgrade of the Large Hadron Collider require improving the beam collimation system. An intense R&D program has started at CERN to explore novel materials for new collimator jaws to improve robustness and reduce impedance. Particle tracking simulations of collimation efficiency are performed using the code MERLIN which has been extended to include new materials based on composites. After presenting two different implementations of composite materials tested in MERLIN, we present simulation studies with the aim of studying the effect of the advanced collimators on the LHC beam cleaning.

  5. Why does the Northern Light shine so brightly?

    DEFF Research Database (Denmark)

    Bjørnskov, Christian; Svendsen, Gert Tinggaard

    2002-01-01

    , means less lobbyism because access to economically harmful rent seeking is more costly. Consequently, social capital and the trust in other people and the political leadership will increase. This model, suggesting one single social capital measure, is applied to countries in both Western and Eastern...

  6. High brightness laser-diode device emitting 500 W from a 200 μm/NA0.22 fiber

    Science.gov (United States)

    Junhong, Yu; Linhui, Guo; Hualing, Wu; Zhao, Wang; Hao, Tan; Songxin, Gao; Deyong, Wu; Kai, Zhang

    2016-06-01

    A practical method of achieving high brightness and high power fiber-coupled laser-diode device is demonstrated both by experiment and ZEMAX software simulation, which is obtained by technologies of precision beam collimation, free space beam combining and polarization beam combining based on mini-bar diode laser chip. Using this method, fiber-coupled laser-diode module output power from the multimode fiber with 200 μm core diameter and 0.22 numerical aperture (NA) could reach 528 W, equalizing brightness is 11.0 MW/(cm2 sr) and electro-optical efficiency (defined as fiber output power divided by voltage and current of the module) is 43.0%. By this method, much wider applications of fiber-coupled laser-diode are anticipated.

  7. But for the bad, there would not be good: Grounding valence in brightness through shared relational structures

    OpenAIRE

    Semin, Gün Refik; Lakens, Daniel; Foroni Francesco

    2011-01-01

    Light and dark are used pervasively to represent positive and negative concepts. Recent studies suggest that black and white stimuli are automatically associated with negativity and positivity. However, structural factors in experimental designs, such as the shared opposition in the valence (good vs. bad) and brightness (light vs. dark) dimensions might play an important role in the valence– brightness association. In 6 experiments, we show that while black ideographs are consistently judged ...

  8. Calculating and measuring thermal neutrons exiting from neutron diffractometers collimators

    CERN Document Server

    Tafazolee, K

    2000-01-01

    process, effectiveness of them are studied for the enhancement of the available system. Final conclusion from the simulation process, indicates that the heavy water with the thickness of 50 to 60 cm. is the best moderator for gaining the better thermal neutrons flux for enhancement of P.N.D. in the T.R.R. Powder Neutron Diffractometer y (P.N.D.) is relatively good and practical way for identification of the 3 dimensional construction of materials. In order to exploit the capabilities of this method, in one of the neutron beam of the Tehran Research Reactor (T.R.R.), a collimator embedded inside the concrete wall, direct the neutrons produced in the core reactor towards a monochromator e. Neutrons having been monochromated by 2 nd collimator are then directed towards the sample. Then the pattern of diffracted neutrons from the sample are studied. In order to make the best out of it, neutrons coming to sit on the sample must be of the thermal type. That means the number/amount of thermal neutrons flux in compar...

  9. Application of multileaf collimator in breast cancer radiation techniques

    Science.gov (United States)

    Janiszewska, Marzena; Dupla, Dorota; Nowakowski, Grzegorz

    2004-07-01

    Modern radiation therapy tools allow a precise delivery of a high dose to a target area (so-called planning target volume -- PTV) and spare, at the same time, critical organs in the vicinity of cancerous lesions. One of the tools of conformal therapy is a multi-leaf collimator, which provides the opportunity to optimally adjust the therapeutic field to the tumor area. More difficult areas for radiation therapy include: mamma, after BCT, and chest after mammectomy with regional lymph nodes. The objective of the study is to present technical and physical aspects of breast carcinoma irradiation when applying a multi-leaf collimator. The following techniques were applied: (a) the isocentric technique of tangent fields (from two to four) for the mamma after BCT; (b) the method of a common isocenter, for the areas of mamma and for regional lymph nodes; (c) the technique of complementary photon + electron fields, for the area of chest after mammectomy and lymph nodes. The presented techniques were implemented as standard procedures in the preparation of breast carcinoma radiation treatment in the Lower Silesian Oncology Center.

  10. Collimation with tighter TCTs at β*=40 cm

    CERN Document Server

    Bruce, Roderik; Kwee-Hinzmann, Regina; Mereghetti, Alessio; Mirarchi, Daniele; Quaranta, Elena; Redaelli, Stefano; Salvachua Ferrando, Belen Maria; Valentino, Gianluca; Valloni, Alessandra; Garcia Morales, Hector; CERN. Geneva. ATS Department

    2015-01-01

    MD 310 was carried out on August 28 2015, in order to investigate the collimation performance using nominal optics with β* =40 cm, 2 σ retraction collimator settings in IR7, and the very tight TCT settings which are necessary to protect the small normalized aperture. With these tight settings, we expect higher losses on the TCTs which should cause also higher beam-halo background at the experiments. During the MD, a total of 70 betatron loss maps were performed over a range of TCT settings and for dierent settings of the TCLAs in IR7. ATLAS and CMS were exceptionally taking data outside stable beams, in order to monitor the background. Furthermore, betatron loss maps were performed with a small momentum oset of the whole beam, induced by a shift of the RF frequency. The MD results can therefore also be used to assess the cleaning eciency in IR7 with the β* =40 cm optics, as well as the eects of energy osets on the cleaning. At the end of the MD, an asynchronous dump test was performed, in order to monitor ...

  11. Design and Performance Optimization of the LHC Collimation System

    CERN Document Server

    Robert-Démolaize, G

    2006-01-01

    The Large Hadron Collider (LHC) is presently under construction at CERN. The LHC is a circular accelerator that stores proton beams and accelerates them to a 7 TeV beam energy. The required bending fields are achieved with super-conducting magnets. The stored proton beams are collided in experimental detectors and produce a design luminosity of 1E+34 cm-2.s-1. Every storage ring encounters unavoidable proton losses. The protons that diffuse into the so-called beam halo can touch accelerator components. In order to avoid quenches of the superconducting magnets, the halo protons must be removed before reaching the magnets. This is achieved with a multi-stage cleaning system, built out of two-sided collimators that are located at adequate positions in the machine. Due to the high stored beam intensity (required for high luminosity), the efficiency of the LHC beam cleaning must be much better than in any other exisiting machine: not more than 0.00002% of protons hitting the collimators may escape and impact on an...

  12. Bright boys the making of information technology

    CERN Document Server

    Green, Tom

    2010-01-01

    Everything has a beginning. None was more profound-and quite as unexpected-than Information Technology. Here for the first time is the untold story of how our new age came to be and the bright boys who made it happen. What began on the bare floor of an old laundry building eventually grew to rival in size the Manhattan Project. The unexpected consequence of that journey was huge---what we now know as Information Technology. For sixty years the bright boys have been totally anonymous while their achievements have become a way of life for all of us. "Bright Boys" brings them home. By 1950 they'd

  13. The structure of bright zinc coatings

    Directory of Open Access Journals (Sweden)

    MIODRAG STOJANOVIC

    2000-11-01

    Full Text Available The structures of bright zinc coatings obtained from acid sulfate solutions in the presence of dextrin/salicyl aldehyde mixture were examined. It was shown by the STM technique that the surfaces of bright zinc coatings are covered by hexagonal zinc crystals, the tops of planes of which are flat and mutually parallel and which exhibit smoothness on the atomic level. X-Ray diffraction (XRD analysis of the bright zinc coatings showed that the zinc crystallites are oriented in the (110 plane only.

  14. South African night sky brightness during high aerosol epochs

    CERN Document Server

    Winkler, Hartmut; Marang, Fred

    2014-01-01

    Sky conditions in the remote, dry north-western interior of South Africa are now the subject of considerable interest in view of the imminent construction of numerous solar power plants in this area. Furthermore, the part of this region in which the core of the SKA is to be located (which includes SALT) has been declared an Astronomical Advantage Zone, for which sky brightness monitoring will now be mandatory. In this project we seek to characterise the sky brightness profile under a variety of atmospheric conditions. Key factors are of course the lunar phase and altitude, but in addition the sky brightness is also significantly affected by the atmospheric aerosol loading, as that influences light beam scattering. In this paper we chose to investigate the sky characteristics soon after the Mount Pinatubo volcanic eruption in 1991, which resulted in huge ash masses reaching the stratosphere (where they affected solar irradiance for several years). We re-reduced photometric sky measurements from the South Afric...

  15. Multi-resolution multi-sensitivity design for parallel-hole SPECT collimators.

    Science.gov (United States)

    Li, Yanzhao; Xiao, Peng; Zhu, Xiaohua; Xie, Qingguo

    2016-07-21

    Multi-resolution multi-sensitivity (MRMS) collimator offering adjustable trade-off between resolution and sensitivity, can make a SPECT system adaptive. We propose in this paper a new idea for MRMS design based on, for the first time, parallel-hole collimators for clinical SPECT. Multiple collimation states with varied resolution/sensitivity trade-offs can be formed by slightly changing the collimator's inner structure. To validate the idea, the GE LEHR collimator is selected as the design prototype and is modeled using a ray-tracing technique. Point images are generated for several states of the design. Results show that the collimation states of the design can obtain similar point response characteristics to parallel-hole collimators, and can be used just like parallel-hole collimators in clinical SPECT imaging. Ray-tracing modeling also shows that the proposed design can offer varied resolution/sensitivity trade-offs: at 100 mm before the collimator, the highest resolution state provides 6.9 mm full width at a half maximum (FWHM) with a nearly minimum sensitivity of about 96.2 cps MBq(-1), while the lowest resolution state obtains 10.6 mm FWHM with the highest sensitivity of about 167.6 cps MBq(-1). Further comparisons of the states on image qualities are conducted through Monte Carlo simulation of a hot-spot phantom which contains five hot spots with varied sizes. Contrast-to-noise ratios (CNR) of the spots are calculated and compared, showing that different spots can prefer different collimation states: the larger spots obtain better CNRs by using the larger sensitivity states, and the smaller spots prefer the higher resolution states. In conclusion, the proposed idea can be an effective approach for MRMS design for parallel-hole SPECT collimators. PMID:27359049

  16. The variability timescales and brightness temperatures of radio flares from stars to supermassive black holes

    CERN Document Server

    Pietka, M; Keane, E F

    2014-01-01

    In this paper we compile the analysis of ~ 200 synchrotron flare events from ~ 90 distinct objects/events for which the distance is well established, and hence the peak luminosity can be accurately estimated. For each event we measure this peak and compare it to the rise and decay timescales, as fit by exponential functions, which allows us in turn to estimate a minimum brightness temperature for all the events. The astrophysical objects from which the flares originate vary from flare stars to supermassive black holes in active galactic nuclei, and include both repeating phenomena and single cataclysmic events (such as supernovae and gamma ray burst afterglows). The measured timescales vary from minutes to longer than years, and the peak radio luminosities range over 22 orders of magnitude. Despite very different underlying phenomena, including relativistic and non-relativistic regimes, and highly collimated versus isotropic phenomena, we find a broad correlation between peak radio luminosity and rise/decay t...

  17. A collimated wind interpretation for the spectral variability of Z And during its major 2006 eruption

    CERN Document Server

    Tomov, N A; Bisikalo, D V

    2016-01-01

    High-resolution observations in the region, centered at 4400 \\AA\\ and those of the lines HeII 4686, Hbeta and HeI 6678 of the spectrum of the symbiotic binary Z And were performed during its outburst in 2006. The line Hbeta had additional satellite high-velocity emission components situated on either side of its central peak. The lines of neutral helium presented two components, consisting of a nebular emission situated close to the reference wavelength and a highly variable P Cyg absorption. Close to the optical maximum the line HeII 4686 was weak emission feature, but with the fading of the light it changed into an intensive emission consisting of a central narrow component and a broad component with a low intensity. The lines of NIII and CIII were very broadened. We demonstrate that all of these groups of lines with very different profiles can be interpreted in the light of the same model, where a disc-shaped material surrounding the compact object collimates its stellar wind and gives rise to bipolar outf...

  18. Brightness of synchrotron radiation from wigglers

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2014-01-01

    According to literature, while calculating the brightness of synchrotron radiation from wigglers, one needs to account for the so called `depth-of-field' effects. In fact, the particle beam cross section varies along the wiggler. It is usually stated that the effective photon source size increases accordingly, while the brightness is reduced. Here we claim that this is a misconception originating from an analysis of the wiggler source based on geometrical arguments, regarded as almost self-evident. According to electrodynamics, depth-of-field effects do not exist: we demonstrate this statement both theoretically and numerically, using a well-known first-principle computer code. This fact shows that under the usually accepted approximations, the description of the wiggler brightness turns out to be inconsistent even qualitatively. Therefore, there is a need for a well-defined procedure for computing the brightness from a wiggler source. We accomplish this task based on the use of a Wigner function formalism. I...

  19. The solar brightness temperature at millimeter wavelengths

    Science.gov (United States)

    Kuseski, R. A.; Swanson, P. N.

    1976-01-01

    Measurements of the brightness temperature of the sun near 36 GHz and 93 GHz were made using the new moon as a calibration source. Provided the brightness temperature of the moon is known and all measurements are reduced to the same zenith angle, a simple expression can be used for the sun-to-new moon ratio which is independent of antenna gain, atmospheric absorption and reemission, and radiometer calibration constants. This ratio was measured near 36 GHz and at two frequencies near 93 GHz with a Dicke switched superheterodyne radiometer system and a 2.4 m Cassegrain antenna. The slopes of the solar brightness temperature spectrum based on these ratios were measured. The absolute solar brightness spectrum derived from all current available measurements supplemented by the present ones is also plotted and discussed.

  20. A spectroscopic atlas of bright stars

    CERN Document Server

    Martin, Jack

    2009-01-01

    Suitable for amateur astronomers interested in practical spectroscopy or spectrography, this reference book identifies more than 70 (northern hemisphere) bright stars that are suitable observational targets. It provides finder charts for locating these sometimes-familiar stars.

  1. Campaign of sky brightness and extinction measurements using a portable CCD camera

    Science.gov (United States)

    Falchi, Fabio

    2011-03-01

    In this paper, we present the results of a 12-yr campaign devoted to monitoring the sky brightness affected by different levels of light pollution. Different sites characterized by different altitudes and atmospheric transparency have been considered. The standard photometric Johnson B and V bands were used. An extinction measurement was performed for each site and each night, along with a calibration of the instrument. These measurements have allowed us to build sky brightness maps of the hemisphere above each observing site; each map contains up to 200 data points spread around the sky. We have found a stop in zenith sky brightness growth at the two sites where a time series exists. Using zenith sky brightness measurements taken with and without extensive snow coverage, we weighted the importance of direct versus indirect flux in producing sky glow at several sites.

  2. High-resolution field shaping utilizing a masked multileaf collimator.

    Science.gov (United States)

    Williams, P C; Cooper, P

    2000-08-01

    Multileaf collimators (MLCs) have become an important tool in the modern radiotherapy department. However, the current limit of resolution (1 cm at isocentre) can be too coarse for acceptable shielding of all fields. A number of mini- and micro-MLCs have been developed, with thinner leaves to achieve approved resolution. Currently however, such devices are limited to modest field sizes and stereotactic applications. This paper proposes a new method of high-resolution beam collimation by use of a tertiary grid collimator situated below the conventional MLC. The width of each slit in the grid is a submultiple of the MLC width. A composite shaped field is thus built up from a series of subfields, with the main MLC defining the length of each strip within each subfield. Presented here are initial findings using a prototype device. The beam uniformity achievable with such a device was examined by measuring transmission profiles through the grid using a diode. Profiles thus measured were then copied and superposed to generate composite beams, from which the uniformity achievable could be assessed. With the average dose across the profile normalized to 100%, hot spots up to 5.0% and troughs of 3% were identified for a composite beam of 2 x 5.0 mm grids, as measured at Dmax for a 6 MV beam. For a beam composed from 4 x 2.5 mm grids, the maximum across the profile was 3.0% above the average, and the minimum 2.5% below. Actual composite profiles were also formed using the integrating properties of film, with the subfield indexing performed using an engineering positioning stage. The beam uniformity for these fields compared well with that achieved in theory using the diode measurements. Finally sine wave patterns were generated to demonstrate the potential improvements in field shaping and conformity using this device as opposed to the conventional MLC alone. The scalloping effect on the field edge commonly seen on MLC fields was appreciably reduced by use of 2 x 5.0 mm

  3. High-resolution field shaping utilizing a masked multileaf collimator.

    Science.gov (United States)

    Williams, P C; Cooper, P

    2000-08-01

    Multileaf collimators (MLCs) have become an important tool in the modern radiotherapy department. However, the current limit of resolution (1 cm at isocentre) can be too coarse for acceptable shielding of all fields. A number of mini- and micro-MLCs have been developed, with thinner leaves to achieve approved resolution. Currently however, such devices are limited to modest field sizes and stereotactic applications. This paper proposes a new method of high-resolution beam collimation by use of a tertiary grid collimator situated below the conventional MLC. The width of each slit in the grid is a submultiple of the MLC width. A composite shaped field is thus built up from a series of subfields, with the main MLC defining the length of each strip within each subfield. Presented here are initial findings using a prototype device. The beam uniformity achievable with such a device was examined by measuring transmission profiles through the grid using a diode. Profiles thus measured were then copied and superposed to generate composite beams, from which the uniformity achievable could be assessed. With the average dose across the profile normalized to 100%, hot spots up to 5.0% and troughs of 3% were identified for a composite beam of 2 x 5.0 mm grids, as measured at Dmax for a 6 MV beam. For a beam composed from 4 x 2.5 mm grids, the maximum across the profile was 3.0% above the average, and the minimum 2.5% below. Actual composite profiles were also formed using the integrating properties of film, with the subfield indexing performed using an engineering positioning stage. The beam uniformity for these fields compared well with that achieved in theory using the diode measurements. Finally sine wave patterns were generated to demonstrate the potential improvements in field shaping and conformity using this device as opposed to the conventional MLC alone. The scalloping effect on the field edge commonly seen on MLC fields was appreciably reduced by use of 2 x 5.0 mm

  4. Solar concentrator with integrated tracking and light delivery system with summation

    Energy Technology Data Exchange (ETDEWEB)

    Maxey, Lonnie Curt

    2015-05-05

    A solar light distribution system includes a solar light concentrator that is affixed externally to a light transfer tube. Solar light waves are processed by the concentrator into a collimated beam of light, which is then transferred through a light receiving port and into the light transfer tube. A reflector redirects the collimated beam of light through the tube to a light distribution port. The interior surface of the light transfer tube is highly reflective so that the light transfers through the tube with minimal losses. An interchangeable luminaire is attached to the light distribution port and provides light inside of a structure. A sun tracking device rotates the concentrator and the light transfer tube to optimize the receiving of solar light by the concentrator throughout the day. The system provides interior lighting that uses only renewable energy sources, and releases no carbon dioxide emissions into the atmosphere.

  5. Development of a high brightness ion source

    International Nuclear Information System (INIS)

    The brightness and emittance of an ion beam can depend on the ion temperature, aberrations and scattering, as well as other factors. However, it is the ion temperature which determines the irreducible minimum value of the emittance and hence brightness, as the other components can be eliminated by careful design. An ion source design is presented which has attained this minimum value for the emittance; the dependence of the ion temperature on the plasma source parameters is discussed

  6. Investigating the fundamentals of IMRT decomposition using ten simple collimator models

    Science.gov (United States)

    Anderson, J. W.; Symonds-Tayler, R.; Webb, S.

    2006-05-01

    The fundamentals of IMRT collimation have been studied using ten conceptual collimators. Spanning a range of complexities from the LINAC jaws alone to a full multi-leaf collimator (MLC), these collimators were designed with two abilities in mind: (1) to be able to define arbitrary field shapes, and (2) to be able to irradiate multiple, disconnected regions in a single segment. The collimators were tested by finding decompositions of random and clinical intensity-modulated beams (IMBs), and collimator performance was measured using both the number of segments required to complete the IMB and the monitor-unit efficiency of the treatment. The decompositions were run on 10 × 10 IMBs with integer bixel values randomly between 1 and 10, and clinical IMBs of varying sizes from lung, head and neck, and pelvic patients taken from a Pinnacle treatment-planning system. Results confirmed that although treatment performance improves with increased collimator complexity, it is not solely dependent on the number of segment shapes deliverable by the collimator but instead on how well these shapes lend themselves to IMRT delivery.

  7. The new world atlas of artificial night sky brightness

    CERN Document Server

    Falchi, Fabio; Duriscoe, Dan; Kyba, Christopher C M; Elvidge, Christopher D; Baugh, Kimberly; Portnov, Boris A; Rybnikova, Nataliya A; Furgoni, Riccardo

    2016-01-01

    Artificial lights raise night sky luminance, creating the most visible effect of light pollution-artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world's land surfaces between 75{\\deg}N and 60{\\deg}S, 88% of Europe, and almost half of the United States experience light-polluted nights.

  8. The new world atlas of artificial night sky brightness.

    Science.gov (United States)

    Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C M; Elvidge, Christopher D; Baugh, Kimberly; Portnov, Boris A; Rybnikova, Nataliya A; Furgoni, Riccardo

    2016-06-01

    Artificial lights raise night sky luminance, creating the most visible effect of light pollution-artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world's land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights. PMID:27386582

  9. The new world atlas of artificial night sky brightness

    Science.gov (United States)

    Falchi, Fabio; Cinzano, Pierantonio; Duriscoe, Dan; Kyba, Christopher C. M.; Elvidge, Christopher D.; Baugh, Kimberly; Portnov, Boris A.; Rybnikova, Nataliya A.; Furgoni, Riccardo

    2016-01-01

    Artificial lights raise night sky luminance, creating the most visible effect of light pollution—artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world’s land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights. PMID:27386582

  10. Collimation of stellar winds by nonadiabatic de Laval nozzles

    International Nuclear Information System (INIS)

    The interaction between an isotropic stellar wind and a stratified environment can lead to the formation of de Laval nozzles (in the adiabatic case) or to the formation of an elongated cavity surrounded by a dense cold shell of shocked gas (in the limit of short cooling distances; i.e., in the highly nonadiabatic case). A preliminary exploration of the intermediate regime between the adiabatic and the highly nonadiabatic regimes yields very interesting results. While for cooling distances larger than about 5 times the environmental scale height the flow resembles the adiabatic de Laval nozzle, for shorter cooling distances the flow is considerably different, leading to the formation of very narrow well collimated cold jets. A preliminary comparison between observations of the HH 1/2 source and radio free-free spectra computed from these models gives very encouraging results. 24 refs

  11. Simulations of the Fermilab Recycler for Losses and Collimation

    Energy Technology Data Exchange (ETDEWEB)

    Stern, Eric [Fermilab; Ainsworth, Robert [Fermilab; Amundson, James [Fermilab; Brown, Bruce [Fermilab

    2015-06-01

    Fermilab has recently completed an upgrade to the com- plex with the goal of delivering 700 kW of beam power as 120 GeV protons to the NuMI target. A major part of boost- ing beam power is to shorten the beam cycle by accumulating up to 12 bunches of 0.5 × 10 11 protons in the Recycler ring through slip-stacking during the Main Injector ramp. This introduces much higher intensities into the Recycler than it has had before. Meeting radiation safety requirements with high intensity operations requires understanding the ef- fects of space charge induced tune spreads and resulting halo formation, and aperture restrictions in the real machine to de- velop a collimation strategy. We report on initial simulations of slip-stacking in the Recycler performed with Synergia.

  12. Augmented reality aiding collimator exchange at the LHC

    International Nuclear Information System (INIS)

    Novel Augmented Reality techniques have the potential to have a large positive impact on the way remote maintenance operations are carried out in hazardous areas, e.g. areas where radiation doses that imply careful planning and optimization of maintenance operations are present. This paper describes an Augmented Reality strategy, system and implementation for aiding the remote collimator exchange in the LHC, currently the world's largest and highest-energy particle accelerator. The proposed system relies on marker detection and multi-modal augmentation in real-time. A database system has been used to ensure flexibility. The system has been tested in a mock-up facility, showing real time performance and great potential for future use in the LHC. The technical-scientific difficulties identified during the development of the system and the proposed solutions described in this paper may help the development of future Augmented Reality systems for remote handling in scientific facilities

  13. Adaptive fiber optics collimator based on flexible hinges.

    Science.gov (United States)

    Zhi, Dong; Ma, Yanxing; Ma, Pengfei; Si, Lei; Wang, Xiaolin; Zhou, Pu

    2014-08-20

    In this manuscript, we present a new design for an adaptive fiber optics collimator (AFOC) based on flexible hinges by using piezoelectric stacks actuators for X-Y displacement. Different from traditional AFOC, the new structure is based on flexible hinges to drive the fiber end cap instead of naked fiber. We fabricated a real AFOC based on flexible hinges, and the end cap's deviation and resonance frequency of the device were measured. Experimental results show that this new AFOC can provide fast control of tip-tilt deviation of the laser beam emitting from the end cap. As a result, the fiber end cap can support much higher power than naked fiber, which makes the new structure ideal for tip-tilt controlling in a high-power fiber laser system.

  14. Solar wind collimation of the Jupiter high velocity dust streams

    Science.gov (United States)

    Flandes, A.; Krueger, H.

    2006-12-01

    The dust bursts discovered by the Ulysses dust sensor when approaching Jupiter in 1992 were later confirmed as collimated streams of high velocity (~200 km/s) charged (~5V) dust grains escaping from Jupiter and dominated by the interplanetary Magnetic field (IMF). With Cassini, a similar phenomenon was observed in Saturn. It was demonstrated that the Jovian dust streams are closely related to the solar wind compressed regions, either Corotating interaction regions (CIRs) or Coronal mass ejections (CMEs) ¨Cto a minor extent-. Actually the dust streams seem ultimately to be generated by such events. This can be explained considering that dust grains are accelerated as they gain substantial energy while compressed at the forward and reverse shocks that bound or precede these solar wind regions.

  15. Fermilab booster operational status: Beam loss and collimation

    Energy Technology Data Exchange (ETDEWEB)

    Robert C. Webber

    2002-06-11

    Beam loss reduction and control challenges confronting the Fermilab Booster are presented in the context of the current operational status. In Summer 2002 the programmatic demand for 8 GeV protons will increase to 5E20/year. This is an order of magnitude above recent high rates and nearly as many protons as the machine has produced in its entire 30-year lifetime. Catastrophic radiation damage to accelerator components must be avoided, maintenance in an elevated residual radiation environment must be addressed, and operation within a tight safety envelope must be conducted to limit prompt radiation in the buildings and grounds around the Booster. Diagnostic and performance tracking improvements, enhanced orbit control, and a beam loss collimation/localization system are essential elements in the approach to achieving the expected level of performance and are described here.

  16. Energy budget in collimated gamma-ray bursts

    International Nuclear Information System (INIS)

    There is increasing evidence for the existence of collimation in some, if not most, of the gamma-ray bursts. This would have direct implications, for instance, on the energy budget, the rate of events, but also indirect consequences for the theoretical models because it provides a tool to differentiate between their predictions. We consider the case of a structured jet, i.e. we assume the energy within the jet varies as a power-law, being a function of the angle between the jet axis and an arbitrary direction. We analyze first the situation in which the jet axis and the line of sight have a particular orientation, then we relax this assumption by allowing for an arbitrary viewing angle with respect to the symmetry axis of the jet. A qualitative study of the total energy content of the jet is performed. It turns out that the 'real' energy could be higher than what is inferred from observations. (authors)

  17. Energy-exchange collisions of dark-bright-bright vector solitons.

    Science.gov (United States)

    Radhakrishnan, R; Manikandan, N; Aravinthan, K

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices. PMID:26764780

  18. Energy-exchange collisions of dark-bright-bright vector solitons

    Science.gov (United States)

    Radhakrishnan, R.; Manikandan, N.; Aravinthan, K.

    2015-12-01

    We find a dark component guiding the practically interesting bright-bright vector one-soliton to two different parametric domains giving rise to different physical situations by constructing a more general form of three-component dark-bright-bright mixed vector one-soliton solution of the generalized Manakov model with nine free real parameters. Moreover our main investigation of the collision dynamics of such mixed vector solitons by constructing the multisoliton solution of the generalized Manakov model with the help of Hirota technique reveals that the dark-bright-bright vector two-soliton supports energy-exchange collision dynamics. In particular the dark component preserves its initial form and the energy-exchange collision property of the bright-bright vector two-soliton solution of the Manakov model during collision. In addition the interactions between bound state dark-bright-bright vector solitons reveal oscillations in their amplitudes. A similar kind of breathing effect was also experimentally observed in the Bose-Einstein condensates. Some possible ways are theoretically suggested not only to control this breathing effect but also to manage the beating, bouncing, jumping, and attraction effects in the collision dynamics of dark-bright-bright vector solitons. The role of multiple free parameters in our solution is examined to define polarization vector, envelope speed, envelope width, envelope amplitude, grayness, and complex modulation of our solution. It is interesting to note that the polarization vector of our mixed vector one-soliton evolves in sphere or hyperboloid depending upon the initial parametric choices.

  19. A column generation approach for evaluating delivery efficiencies of collimator technologies in IMRT treatment planning

    International Nuclear Information System (INIS)

    Collimator systems used in Intensity Modulated Radiation Therapy can form different geometric aperture shapes depending on their physical capabilities. We compare the efficiency of using regular, rotating and dual multileaf collimator (MLC) systems under different combinations of consecutiveness, interdigitation and rectangular constraints. We also create a virtual freeform collimator, which can form any possible segment shape by opening or closing each bixel independently, to provide a basis for comparison. We formulate the problem of minimizing beam-on time as a large-scale linear programming problem. To deal with its dimensionality, we propose a column generation approach. We demonstrate the efficacy of our approach on a set of clinical problem instances. Our results indicate that the dual MLC under consecutiveness constraint yields very similar beam-on time to a virtual freeform collimator. Our approach also provides a ranking between other collimator technologies in terms of their delivery efficiencies. (paper)

  20. A new CT collimator for producing two simultaneous overlapping slices from one scan. [for biomedical applications

    Science.gov (United States)

    Kwoh, Y. S.; Glenn, W. V., Jr.; Reed, I. S.; Truong, T. K.

    1981-01-01

    A new CT collimator is developed which is capable of producing two simultaneous successive overlapping images from a single scan. The collimator represents a modification of the standard EMI 5005 collimator achieved by alternately masking one end or portions of both ends of the X-ray detectors at a 13-mm beamwidth so that a set of 540 filtered projections is obtained for each scan which can be separated into two sets of interleaved projections corresponding to views 3 mm apart. Tests have demonstrated that the quality of the images produced from these two projections almost equals the quality of those produced by the standard collimator from two separate scans. The new collimator may thus be used to achieve a speed improvement in the generation of overlapping sections as well as a reduction in X-ray dosage.

  1. Observation of strong leakage reduction in crystal assisted collimation of the SPS beam

    Energy Technology Data Exchange (ETDEWEB)

    Scandale, W. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Laboratoire de l' Accelerateur Lineaire (LAL), Universite Paris Sud Orsay, Orsay (France); INFN Sezione di Roma, Piazzale Aldo Moro 2, 00185 Rome (Italy); Arduini, G.; Butcher, M.; Cerutti, F.; Garattini, M.; Gilardoni, S.; Lechner, A.; Losito, R.; Masi, A.; Mereghetti, A.; Metral, E. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Mirarchi, D. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Imperial College, London (United Kingdom); Montesano, S.; Redaelli, S. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Rossi, R. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); INFN Sezione di Roma, Piazzale Aldo Moro 2, 00185 Rome (Italy); Schoofs, P.; Smirnov, G. [CERN, European Organization for Nuclear Research, CH-1211 Geneva 23 (Switzerland); Bagli, E.; Bandiera, L.; Baricordi, S. [INFN Sezione di Ferrara, Dipartimento di Fisica, Università di Ferrara, Ferrara (Italy); and others

    2015-09-02

    In ideal two-stage collimation systems, the secondary collimator–absorber should have its length sufficient to exclude practically the exit of halo particles with large impact parameters. In the UA9 experiments on the crystal assisted collimation of the SPS beam a 60 cm long tungsten bar is used as a secondary collimator–absorber which is insufficient for the full absorption of the halo protons. Multi-turn simulation studies of the collimation allowed to select the position for the beam loss monitor downstream the collimation area where the contribution of particles deflected by the crystal in channeling regime but emerging from the secondary collimator–absorber is considerably reduced. This allowed observation of a strong leakage reduction of halo protons from the SPS beam collimation area, thereby approaching the case with an ideal absorber.

  2. Collimation Down to 2 Sigma in Special Physics Runs in the LHC

    CERN Document Server

    Burkhardt, H; Salvachua, B; Valentino, G

    2013-01-01

    We report on observations with collimation very close to the beam. Primary collimators were moved in small steps down to 2 σ from the beam axis to allow for measurements of very forward proton scattering in special highbeta runs in the LHC. We studied the reduction in intensity as a function of collimator position which provides information about the halo shape. After scraping at 2σ, collimators were retracted to 2:5 σ. This allowed for measurements of very forward proton-proton scattering with roman pot detectors at 3 σ from the beam axis at acceptable background levels for about an hour. Good background conditions were restored by another scraping with primary collimators at 2 σ. Beam lifetimes and halo repopulation times were found to be sufficiently long to allow for several hours of data taking between scraping in a single LHC fill.

  3. Calculation of effective dose in whole body in dependence of angle of collimator for photon fields

    Energy Technology Data Exchange (ETDEWEB)

    Fuenzalida, M. [Universidad de la Frontera, Temuco (Chile). Programa de Magister en Fisica Medica; Varon, C.; Piriz, G.; Banguero, Y.; Lozano, E.; Mancilla, C., E-mail: fisicamedica@incancer.c [Instituto Nacional del Cancer, Santiago (Chile). Unidad de Fisica Medica

    2011-07-01

    The objective of this work is to obtain quantifiable data of whole body effective dose for photons fields of 6 MV and 18 MV in function of the collimator angle of a Varian Clinac 21EX lineal accelerator. It has been made a variety of studies which investigate the form to reduce the dose in whole body with photons fields, specially over the potential risks and the influence of the collimator angle, as performed Stanthakis et al. [1] with the Monte Carlo method. As a result of this work, the values of whole body effective doses are higher with a 0 deg collimator than with a 90 deg collimator, and as the field size increases, the effective doses difference in whole body, between 0 deg and 90 deg collimator angle, for both energies, becomes smaller. (author)

  4. Observation of strong leakage reduction in crystal assisted collimation of the SPS beam

    Directory of Open Access Journals (Sweden)

    W. Scandale

    2015-09-01

    Full Text Available In ideal two-stage collimation systems, the secondary collimator–absorber should have its length sufficient to exclude practically the exit of halo particles with large impact parameters. In the UA9 experiments on the crystal assisted collimation of the SPS beam a 60 cm long tungsten bar is used as a secondary collimator–absorber which is insufficient for the full absorption of the halo protons. Multi-turn simulation studies of the collimation allowed to select the position for the beam loss monitor downstream the collimation area where the contribution of particles deflected by the crystal in channeling regime but emerging from the secondary collimator–absorber is considerably reduced. This allowed observation of a strong leakage reduction of halo protons from the SPS beam collimation area, thereby approaching the case with an ideal absorber.

  5. Preliminary thermo-mechanical analysis of angular beam impact on LHC collimators

    CERN Document Server

    Cauchi, M; Bertarelli, A; Carra, F; Dallocchio, A; Deboy, D; Mariani, N; Rossi, A; Lari, L; Mollicone, P; Sammut, N

    2012-01-01

    The correct functioning of the LHC Collimation System is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, accident scenarios must be well studied in order to assess their effect on the robustness of the collimators. One of the most probable accident scenarios identified is an asynchronous beam dump coupled with slight angular misalignment errors of the collimator installation at the beam-line. Previous work presented a preliminary thermal evaluation of the extent of beam-induced damage for such scenarios, where it was shown that in some cases, a tilt of the jaw could actually serve to mitigate the effect of an asynchronous dump on the collimators. This paper will further analyze the response of tertiary collimators in presence of such angular jaw alignments. Such work will also help to start identifying optimal operational conditions.

  6. Note: Detector collimators for the nanoscale ordered materials diffractometer instrument at the Spallation Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Tamalonis, A. [Materials Development, Inc., Arlington Heights, Illinois 60004, USA; Weber, J. K. R. [Materials Development, Inc., Arlington Heights, Illinois 60004, USA; Argonne National Laboratory, Argonne, Illinois 60439, USA; Neuefeind, J. C. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA; Carruth, J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, USA; Skinner, L. B. [Materials Development, Inc., Arlington Heights, Illinois 60004, USA; Argonne National Laboratory, Argonne, Illinois 60439, USA; Stony Brook University, Stony Brook, New York 11794, USA; Alderman, O. L. G. [Materials Development, Inc., Arlington Heights, Illinois 60004, USA; Argonne National Laboratory, Argonne, Illinois 60439, USA; Benmore, C. J. [Argonne National Laboratory, Argonne, Illinois 60439, USA

    2015-09-01

    Five neutron collimator designs were constructed and tested at the nanoscale ordered materials diffractometer (NOMAD) instrument. Collimators were made from High Density PolyEthylene (HDPE) or 5% borated HDPE. In all cases, collimators improved the signal to background ratio and reduced detection of secondary scattering. In the Q-range 10-20 (angstrom)-1, signal to background ratio improved by factors of approximately 1.6 and 2.0 for 50 and 100 mm deep collimators, respectively. In the Q-range 40-50 angstrom-1, the improvement factors were 1.8 and 2.7. Secondary scattering as measured at Q similar to 9.5 angstrom-1 was significantly decreased when the collimators were installed.

  7. Note: Detector collimators for the nanoscale ordered materials diffractometer instrument at the Spallation Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Tamalonis, A. [Materials Development, Inc., Arlington Heights, Illinois 60004 (United States); Weber, J. K. R., E-mail: rweber@anl.gov; Alderman, O. L. G. [Materials Development, Inc., Arlington Heights, Illinois 60004 (United States); Argonne National Laboratory, Argonne, Illinois 60439 (United States); Neuefeind, J. C.; Carruth, J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (United States); Skinner, L. B. [Materials Development, Inc., Arlington Heights, Illinois 60004 (United States); Argonne National Laboratory, Argonne, Illinois 60439 (United States); Stony Brook University, Stony Brook, New York 11794 (United States); Benmore, C. J. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

    2015-09-15

    Five neutron collimator designs were constructed and tested at the nanoscale ordered materials diffractometer (NOMAD) instrument. Collimators were made from High Density PolyEthylene (HDPE) or 5% borated HDPE. In all cases, collimators improved the signal to background ratio and reduced detection of secondary scattering. In the Q-range 10-20 Å{sup −1}, signal to background ratio improved by factors of approximately 1.6 and 2.0 for 50 and 100 mm deep collimators, respectively. In the Q-range 40-50 Å{sup −1}, the improvement factors were 1.8 and 2.7. Secondary scattering as measured at Q ∼ 9.5 Å{sup −1} was significantly decreased when the collimators were installed.

  8. Parametrization and application of scatter kernels for modelling scanned proton beam collimator scatter dose

    Science.gov (United States)

    Kimstrand, Peter; Traneus, Erik; Ahnesjö, Anders; Tilly, Nina

    2008-07-01

    Collimators are routinely used in proton radiotherapy to laterally confine the field and improve the penumbra. Collimator scatter contributes up to 15% of the local dose and is therefore important to include in treatment planning dose calculation. We present a method for reconstruction of the collimator scatter phase space based on the parametrization of pre-calculated scatter kernels. Collimator scatter distributions, generated by the Monte Carlo (MC) package GEANT4.8.2, were scored differential in direction and energy. The distributions were then parametrized so as to enable a fast reconstruction by sampling. MC calculated dose distributions in water based on the parametrized phase space were compared to full MC simulations that included the collimator in the simulation geometry, as well as to experimental data. The experiments were performed at the scanned proton beam line at the The Svedberg Laboratory (TSL) in Uppsala, Sweden. Dose calculations using the parametrization of this work and the full MC for isolated typical cases of collimator scatter were compared by means of the gamma index. The result showed that in total 96.7% (99.3%) of the voxels fulfilled the gamma 2.0%/2.0 mm (3.0%/3.0 mm) criterion. The dose distribution for a collimated field was calculated based on the phase space created by the collimator scatter model incorporated into the generation of the phase space of a scanned proton beam. Comparing these dose distributions to full MC simulations, including particle transport in the MLC, yielded that in total for 18 different collimated fields, 99.1% of the voxels satisfied the gamma 1.0%/1.0 mm criterion and no voxel exceeded the gamma 2.6%/2.6 mm criterion. The dose contribution of collimator scatter along the central axis as predicted by the model showed good agreement with experimental data.

  9. An Optically Stabilized Fast-Switching Light Emitting Diode as a Light Source for Functional Neuroimaging

    OpenAIRE

    Wagenaar, Daniel A.

    2012-01-01

    Neuroscience research increasingly relies on optical methods for evoking neuronal activity as well as for measuring it, making bright and stable light sources critical building blocks of modern experimental setups. This paper presents a method to control the brightness of a high-power light emitting diode (LED) light source to an unprecedented level of stability. By continuously monitoring the actual light output of the LED with a photodiode and feeding the result back to the LED's driver by ...

  10. Collimator optimization and collimator-detector response compensation in myocardial perfusion SPECT using the ideal observer with and without model mismatch and an anthropomorphic model observer

    Science.gov (United States)

    Ghaly, Michael; Links, Jonathan M.; Frey, Eric C.

    2016-03-01

    The collimator is the primary factor that determines the spatial resolution and noise tradeoff in myocardial perfusion SPECT images. In this paper, the goal was to find the collimator that optimizes the image quality in terms of a perfusion defect detection task. Since the optimal collimator could depend on the level of approximation of the collimator-detector response (CDR) compensation modeled in reconstruction, we performed this optimization for the cases of modeling the full CDR (including geometric, septal penetration and septal scatter responses), the geometric CDR, or no model of the CDR. We evaluated the performance on the detection task using three model observers. Two observers operated on data in the projection domain: the Ideal Observer (IO) and IO with Model-Mismatch (IO-MM). The third observer was an anthropomorphic Channelized Hotelling Observer (CHO), which operated on reconstructed images. The projection-domain observers have the advantage that they are computationally less intensive. The IO has perfect knowledge of the image formation process, i.e. it has a perfect model of the CDR. The IO-MM takes into account the mismatch between the true (complete and accurate) model and an approximate model, e.g. one that might be used in reconstruction. We evaluated the utility of these projection domain observers in optimizing instrumentation parameters. We investigated a family of 8 parallel-hole collimators, spanning a wide range of resolution and sensitivity tradeoffs, using a population of simulated projection (for the IO and IO-MM) and reconstructed (for the CHO) images that included background variability. We simulated anterolateral and inferior perfusion defects with variable extents and severities. The area under the ROC curve was estimated from the IO, IO-MM, and CHO test statistics and served as the figure-of-merit. The optimal collimator for the IO had a resolution of 9-11 mm FWHM at 10 cm, which is poorer resolution than typical collimators

  11. Ultra Low Surface Brightness Imaging with the Dragonfly Telephoto Array

    CERN Document Server

    Abraham, Roberto G

    2014-01-01

    We describe the Dragonfly Telephoto Array, a robotic imaging system optimized for the detection of extended ultra low surface brightness structures. The array consists of eight Canon 400mm f/2.8 telephoto lenses coupled to eight science-grade commercial CCD cameras. The lenses are mounted on a common framework and are co-aligned to image simultaneously the same position on the sky. The system provides an imaging capability equivalent to a 0.4m aperture f/1.0 refractor with a 2.6 deg X 1.9 deg field of view. The system has no obstructions in the light path, optimized baffling, and internal optical surfaces coated with a new generation of anti-reflection coatings based on sub-wavelength nanostructures. As a result, the array's point spread function has a factor of ~10 less scattered light at large radii than well-baffled reflecting telescopes. The Dragonfly Telephoto Array is capable of imaging extended structures to surface brightness levels below 30 mag/arcsec^2 in 10h integrations (without binning or foregro...

  12. A Bright Single Photon Source Based on a Diamond Nanowire

    CERN Document Server

    Babinec, T; Khan, M; Zhang, Y; Maze, J; Hemmer, P R; Loncar, M

    2009-01-01

    The development of a robust light source that emits one photon at a time is an outstanding challenge in quantum science and technology. Here, at the transition from many to single photon optical communication systems, fully quantum mechanical effects may be utilized to achieve new capabilities, most notably perfectly secure communication via quantum cryptography. Practical implementations place stringent requirements on the device properties, including fast and stable photon generation, efficient collection of photons, and room temperature operation. Single photon light emitting devices based on fluorescent dye molecules, quantum dots, nanowires, and carbon nanotube material systems have all been explored, but none have simultaneously demonstrated all criteria. Here, we describe the design, fabrication, and characterization of a bright source of single photons consisting of an individual Nitrogen-vacancy color center (NV center) in a diamond nanowire operating in ambient conditions. The nanowire plays a posit...

  13. Quantifying light pollution

    International Nuclear Information System (INIS)

    In this paper we review new available indicators useful to quantify and monitor light pollution, defined as the alteration of the natural quantity of light in the night environment due to introduction of manmade light. With the introduction of recent radiative transfer methods for the computation of light pollution propagation, several new indicators become available. These indicators represent a primary step in light pollution quantification, beyond the bare evaluation of the night sky brightness, which is an observational effect integrated along the line of sight and thus lacking the three-dimensional information. - Highlights: • We review new available indicators useful to quantify and monitor light pollution. • These indicators are a primary step in light pollution quantification. • These indicators allow to improve light pollution mapping from a 2D to a 3D grid. • These indicators allow carrying out a tomography of light pollution. • We show an application of this technique to an Italian region

  14. Bright perspectives for nuclear photonics

    International Nuclear Information System (INIS)

    With the advent of new high-power, short-pulse laser facilities in combination with novel technologies for the production of highly brilliant, intense γ beams (like, e.g., Extreme Light Infrastructure - Nuclear Physics (ELI-NP) in Bucharest, MEGaRay in Livermore or a planned upgrade of the HIγS facility at Duke University), unprecedented perspectives will open up in the coming years for photonuclear physics both in basic sciences as in various fields of applications. Ultra-high sensitivity will be enabled by an envisaged increase of the γ-beam spectral density from the presently typical 102γ/eVs to about 104γ/eVs, thus enabling a new quality of nuclear photonics, assisted by new γ-optical elements. Photonuclear reactions with highly brilliant γ beams will allow to produce radioisotopes for nuclear medicine with much higher specific activity and/or more economically than with conventional methods. This will open the door for completely new clinical applications of radioisotopes. The isotopic, state-selective sensitivity of the well-established technique of nuclear resonance fluorescence (NRF) will be boosted by the drastically reduced energy bandwidth (<0.1%) of the novel γ beams. Together with a much higher intensity of these beams, this will pave the road towards a γ-beam based non-invasive tomography and microscopy, assisting the management of nuclear materials, such as radioactive waste management, the detection of nuclear fissile material in the recycling process or the detection of clandestine fissile materials. Moreover, also secondary sources like low-energy, pulsed, polarized neutron beams of high intensity and high brilliance or a new type of positron source with significantly increased brilliance, for the first time fully polarized, can be realized and lead to new applications in solid state physics or material sciences. (authors)

  15. Spectroscopic Surface Brightness Fluctuations: Amplifying Bright Stars in Unresolved Stellar Populations

    Science.gov (United States)

    Mitzkus, M.; Dreizler, S.; Roth, M. M.

    2015-08-01

    We report on our early-stage efforts to resolve the Surface Brightness Fluctuations (SBFs) in the spectral dimension. Combining the diagnostic power of SBFs with the physical information content of spectra seems a tempting possibility to gain new insights into the bright stars in unresolved stellar populations. The new VLT integral field spectrograph MUSE is the first instrument that enables spectroscopic SBFs observationally.

  16. THE TULLY-FISHER RELATION FOR LOW SURFACE BRIGHTNESS GALAXIES - IMPLICATIONS FOR GALAXY EVOLUTION

    NARCIS (Netherlands)

    Zwaan, M.A.; VAN DER HULST, JM; DE BLOK, WJG; MCGAUGH, SS

    1995-01-01

    We present the B-band Tully-Fisher relation for low surface brightness (LSB) galaxies. These LSB galaxies follow the same Tully-Fisher relation as normal spiral galaxies. This implies that the mass-to-light ratio (M/L) of LSB galaxies is typically a factor of 2 larger than that of normal galaxies of

  17. Beam feasibility study of a collimator with in-jaw beam position monitors

    Science.gov (United States)

    Wollmann, Daniel; Nosych, Andriy A.; Valentino, Gianluca; Aberle, Oliver; Aßmann, Ralph W.; Bertarelli, Alessandro; Boccard, Christian; Bruce, Roderik; Burkart, Florian; Calvo, Eva; Cauchi, Marija; Dallocchio, Alessandro; Deboy, Daniel; Gasior, Marek; Jones, Rhodri; Kain, Verena; Lari, Luisella; Redaelli, Stefano; Rossi, Adriana

    2014-12-01

    At present, the beam-based alignment of the LHC collimators is performed by touching the beam halo with both jaws of each collimator. This method requires dedicated fills at low intensities that are done infrequently and makes this procedure time consuming. This limits the operational flexibility, in particular in the case of changes of optics and orbit configuration in the experimental regions. The performance of the LHC collimation system relies on the machine reproducibility and regular loss maps to validate the settings of the collimator jaws. To overcome these limitations and to allow a continuous monitoring of the beam position at the collimators, a design with jaw-integrated Beam Position Monitors (BPMs) was proposed and successfully tested with a prototype (mock-up) collimator in the CERN SPS. Extensive beam experiments allowed to determine the achievable accuracy of the jaw alignment for single and multi-turn operation. In this paper, the results of these experiments are discussed. The non-linear response of the BPMs is compared to the predictions from electromagnetic simulations. Finally, the measured alignment accuracy is compared to the one achieved with the present collimators in the LHC.

  18. Collimator design for a multipinhole brain SPECT insert for MRI

    Energy Technology Data Exchange (ETDEWEB)

    Van Audenhaege, Karen; Van Holen, Roel; Vanhove, Christian; Vandenberghe, Stefaan [Department of Electronics and Information Systems, Ghent University-iMinds Medical IT, MEDISIP-IBiTech, De Pintelaan 185 block B/5, Ghent B-9000 (Belgium)

    2015-11-15

    Purpose: Brain single photon emission computed tomography (SPECT) imaging is an important clinical tool, with unique tracers for studying neurological diseases. Nowadays, most commercial SPECT systems are combined with x-ray computed tomography (CT) in so-called SPECT/CT systems to obtain an anatomical background for the functional information. However, while CT images have a high spatial resolution, they have a low soft-tissue contrast, which is an important disadvantage for brain imaging. Magnetic resonance imaging (MRI), on the other hand, has a very high soft-tissue contrast and does not involve extra ionizing radiation. Therefore, the authors designed a brain SPECT insert that can operate inside a clinical MRI. Methods: The authors designed and simulated a compact stationary multipinhole SPECT insert based on digital silicon photomultiplier detector modules, which have shown to be MR-compatible and have an excellent intrinsic resolution (0.5 mm) when combined with a monolithic 2 mm thick LYSO crystal. First, the authors optimized the different parameters of the SPECT system to maximize sensitivity for a given target resolution of 7.2 mm in the center of the field-of-view, given the spatial constraints of the MR system. Second, the authors performed noiseless simulations of two multipinhole configurations to evaluate sampling and reconstructed resolution. Finally, the authors performed Monte Carlo simulations and compared the SPECT insert with a clinical system with ultrahigh-resolution (UHR) fan beam collimators, based on contrast-to-noise ratio and a visual comparison of a Hoffman phantom with a 9 mm cold lesion. Results: The optimization resulted in a stationary multipinhole system with a collimator radius of 150.2 mm and a detector radius of 172.67 mm, which corresponds to four rings of 34 diSPM detector modules. This allows the authors to include eight rings of 24 pinholes, which results in a system volume sensitivity of 395 cps/MBq. Noiseless simulations

  19. Collimator design for a multipinhole brain SPECT insert for MRI

    International Nuclear Information System (INIS)

    Purpose: Brain single photon emission computed tomography (SPECT) imaging is an important clinical tool, with unique tracers for studying neurological diseases. Nowadays, most commercial SPECT systems are combined with x-ray computed tomography (CT) in so-called SPECT/CT systems to obtain an anatomical background for the functional information. However, while CT images have a high spatial resolution, they have a low soft-tissue contrast, which is an important disadvantage for brain imaging. Magnetic resonance imaging (MRI), on the other hand, has a very high soft-tissue contrast and does not involve extra ionizing radiation. Therefore, the authors designed a brain SPECT insert that can operate inside a clinical MRI. Methods: The authors designed and simulated a compact stationary multipinhole SPECT insert based on digital silicon photomultiplier detector modules, which have shown to be MR-compatible and have an excellent intrinsic resolution (0.5 mm) when combined with a monolithic 2 mm thick LYSO crystal. First, the authors optimized the different parameters of the SPECT system to maximize sensitivity for a given target resolution of 7.2 mm in the center of the field-of-view, given the spatial constraints of the MR system. Second, the authors performed noiseless simulations of two multipinhole configurations to evaluate sampling and reconstructed resolution. Finally, the authors performed Monte Carlo simulations and compared the SPECT insert with a clinical system with ultrahigh-resolution (UHR) fan beam collimators, based on contrast-to-noise ratio and a visual comparison of a Hoffman phantom with a 9 mm cold lesion. Results: The optimization resulted in a stationary multipinhole system with a collimator radius of 150.2 mm and a detector radius of 172.67 mm, which corresponds to four rings of 34 diSPM detector modules. This allows the authors to include eight rings of 24 pinholes, which results in a system volume sensitivity of 395 cps/MBq. Noiseless simulations

  20. Observing Faint Companions Close to Bright Stars

    Science.gov (United States)

    Serabyn, Eugene

    2012-04-01

    Progress in a number of technical areas is enabling imaging and interferometric observations at both smaller angular separations from bright stars and at deeper relative contrast levels. Here we discuss recent progress in several ongoing projects at the Jet Propulsion Laboratory. First, extreme adaptive optics wavefront correction has recently enabled the use of very short (i.e., blue) wavelengths to resolve close binaries. Second, phase-based coronagraphy has recently allowed observations of faint companions to within nearly one diffraction beam width of bright stars. Finally, rotating interferometers that can observe inside the diffraction beam of single aperture telescopes are being developed to detect close-in companions and bright exozodiacal dust. This paper presents a very brief summary of the techniques involved, along with some illustrative results.