HgCdTe 256x256 NWIR FPA

Researchers developed a HgCdTe 256x256 focal plane array (FPA) which operates in the 1 to 5 micron band. This is presently the largest demonstrated HgCdTe FPA. The detector material is HgCdTe on sapphire (PACE-1 technology) which has a low thermal expansion mismatch with silicon. The multiplexer is a CMOS FET-switch device processed through a commercial silicon foundry. The multiplexer input is direct injection and the charge capacity is about 2 times 10 to the 7th power electrons. The kTC limited read noise is 400 electrons. Researchers demonstrated high background imaging using the device. The broadband quantum efficiency is measured to be 59 percent. Dark currents less than 0.1 pA were measured at 77 K for detectors processed on PACE-1 material with 4.9 microns cutoff. The dark currents decrease as the temperature is lowered, and researchers are presently studying the T less than 77 K characteristics. The interconnect yield is greater than 95 percent. The devices are available for astronomical applications

II. Dünya Savaşı Türkiyesi'nde Bir Muhalefet Örneği Olarak " Tan Gazetesi \"

II. Dünya Savaşı boyunca Türkiye'nin yaşadığı iç ve dış sorunlara karşı ülkenin tepkisinibasın yansıtır. Bu dönemin bir bakıma nabzını yoklamak için basın en önemli kaynakniteliğindedir. Tan gazetesi II. Dünya Savaşı yıllarında ülkenin en çok satan gazeteleriarasında yer alır ve kamuoyunun oluşturulmasında etkili olur. Gazetenin güttüğü politikaiki noktada toplanır: Sovyet dostluğu ve faşizm düşmanlığı. Gazetenin savaş yıllarındakipolitikası ise savaşın başından beri Sovyetler Birliği'ne sempati beslemek olmuş ve bu durumhaberler ve başyazılarla desteklenmişti. Savaş boyunca Tan gazetesi, Sovyetler Birliği'ne karşıyapılmış olan propagandayı silmeye, Sovyetlere karşı sevgi yaratmaya çalışıyordu. Savaşıngidişatına bağlı olarak Türkiye'de aşırı sağ akımlar gelişmeye başlayınca Tan gazetesindeırkçılığı yeren makalelerin daha çok çıktığını görülür. Bu nedenle gazete savaş yıllarındaTurancı akımların hedefi haline gelmiştir. II. Dünya Savaşı'nın sonlarına doğru ise SovyetlerBirliği ile olan ilişkilerin bozulmaya başlaması ve bu sırada Tan gazetesinin çok partili hayatageçişi ve demokrasiyi savunması, gazeteye karşı olan tepkileri daha da artırmış ve komünistliksuçlamalarının yoğunlaşmasına neden olur

Low noise HgCdTe 128 x 128 SWIR FPA for Hubble space telescope

Large area focal plane arrays of unprecedented performance were developed for use in Near Infrared Camera and Multi-Object Spectrometer (NICMOS), a proposed Hubble Space Telescope refurbishment instrument. These FPAs are 128x128-element, HgCdTe hybrid arrays with a cutoff wavelength of 2.5 microns. The multiplexer consists of a CMOS field effect transistor switch array with a typical mean readout noise of less than 30 electrons. The detectors typically have a mean dark current of less than 10 electrons/s at 77 K, with currents below 2 electrons measured at 60 K (both at 0.5 V reverse bias). The mean quantum efficiency is 40 to 60 percent at 77 K for 1.0 to 2.4 microns. Functional pixel yield is typically greater than 99 percent, and the power consumption is approximately 0.2 mW (during readout only)

Laboratory and telescope use of the NICMOS2 128 x 128 HgCdTe array

The second generation of Hubble Space Telescope (HST) instruments will include a near-infrared instrument. This choice has driven the development of near-infrared arrays to larger sizes and lower read noises. Rockwell International has delivered an array for use in the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument; this array has been dubbed NICMOS2. NICMOS2 is a 128x128 array of HgCdTe diodes In-bonded to a switched MOSFET readout. The readout was specifically designed for astronomical use with the HST requirement of low read noise a prime goal. These arrays use detector material which is similar to that used by Rockwell in previous arrays (e.g., HgCdTe produced on a sapphire substrate), but the NICMOS2 devices differ substantially from other 128x128 arrays produced by Rockwell in having a read noise of only 30 electrons when read out using appropriate correlated sampling. NICMOS2 has now been characterized in the laboratory, and it has been used on groundbased telescopes

Magnetic domain wall dynamics in the presence of an in-plane field

The purpose of this work is to understand the domain wall dynamics in the presence of high drive fields and inplane fields in magnetic bubble materials. Bubble radial expansion method is used to investigate the non-linear region. Saturation velocity is found at low in-plane fields and a drive dependent region at higher in-plane fields. The in-plane field increases all the velocities. There is velocity anisotropy and the wall along the in-plane field generally has a higher velocity than the one normal to it. The domain wall is dynamically deformed through the thickness at high drive and in-plane fields. This deformation is studied in the bulk of the film by transmission (Faraday) mode and at the surfaces by reflection (Kerr) mode. The mechanism for the deformation is based on the spatial variations of the effective in-plane field through the thickness. This causes different parts of the wall to move with different velocities resulting in a deformed wall. The characteristics of the deformed wall are studied in detail for several samples