Long-distance drifting of ionization electrons in liquid and solid argon

Summary A study of ionization electron drifting long distances in liquid and solid argon was carried out with a 10 cm gridded ionization chamber, operated with electric fields between 10 V/cm and 2 kV/cm. A detailed analysis of the ionization pulse shape was performed with a FADC readout, yielding information on both the degree of purity of the liquid and the electron drift velocity. Argon with an impurity concentration less than 0.2 p.p.b. oxygen equivalent was obtained with a very simple purification system. With this level of purity electrons remained free for periods of time in excess of one millisecond. The measured attenuation length extrapolates to 7.5 m for liquid argon and to 1 m for solid argon at a drift field of 1 kV/cm. This work was supported by the U.S. Department of Energy under contract number DE-AC02-76ER03064.     

Study of a multi-wire proportional chamber with a cathode strip and delay-line readout

The design principle for a multi-wire proportional chamber with a cathode strip and delay-line readout is described. A prototype chamber of a size of 10 cm ～ l0 cm was made together with the readout electronics circuit. A very clean signal with very low background noise was obtained by applying a transformer between the delay-line and the pre-amplifier in order to match the resistance. Along the anode wire direction a position resolution of less than 0.5 mm was achieved with a 55Fe-5.9 keV X ray source. The simple structure, large effective area and high position resolution allow the application of a gas chamber of this kind to many purposes.     

布喇格条件下二步补偿像差

提出了一种二步记录的全息像差补偿方法,它用短波长(540nm以下)制作,而在长波长(红光或红外光)再现时具有较高的衍射效率和较小的像差,且能适用于任意给定的使用条件,最后给出了计算结果和理论结果.     

Holographic read-only memory

We describe the three-dimensional holographic optical disc system for application as read-only memory. Several systems design issues are discussed including imaging optics, storage density, readout rate, and the alignment servo system. We demonstrate 40 bits/m² surface density and pixel-matched holographic data readout from a 12 cm disc spinning at 600 RPM.     

Storing optical information as a mechanical excitation in a silica optomechanical resonator

We report the experimental demonstration of storing optical information as a mechanical excitation in a silica optomechanical resonator. We use writing and readout laser pulses tuned to one mechanical frequency below an optical cavity resonance to control the coupling between the mechanical displacement and the optical field at the cavity resonance. The writing pulse maps a signal pulse at the cavity resonance to a mechanical excitation. The readout pulse later converts the mechanical excitation back to an optical pulse. The storage lifetime is determined by the relatively long damping time of the mechanical excitation.     

GdFeCo/AlN/TbFeCo薄膜的变温磁化性能研究

用磁控溅射法制备了GdFeCo/AlN/TbFeCo静磁耦合多层薄膜。振动样品磁强计和克尔磁滞回线测试装置的测试结果表明 :2 5℃不加外磁场时GdFeCo/AlN/TbFeCo静磁耦合多层薄膜读出层 (GdFeCo)的极向克尔角为零 ,读出层呈平面磁化 ;12 5℃不加外场时读出层的克尔角最大 (0 .5 4°) ,读出层的磁化方向为垂直磁化 ;随着温度增高 ,读出层由平面磁化转变为垂直磁化 ,在 75℃到 12 5℃温度范围内读出层磁化方向很快从平面磁化转变为垂直磁化。对磁化过程的机理研究表明 :饱和磁化强度和有效各向异性常量影响读出层磁化方向的转变过程 ,但主要受读出层饱和磁化强度的影响 ;在较高温度时读出层的磁化强度较小 ,退磁场能较小 ,在静磁耦合作用下 ,使GdFeCo读出层的磁化方向发生转变。制备的GdFeCo/AlN/TbFeCo静磁耦合多层薄膜适合作CAD MSR记录介质     

非制冷红外探测器读出电路的非均匀性研究

对于长线列的非制冷红外探测器组件, 不同探测元之间的非均匀性是衡量电路设计的关键指标. 为了实现长线列非制冷红外探测器的高性能读出, 本文设计了一种基于电流镜方式的非制冷红外探测器160线列读出电路, 电路由电流镜输入模块、电容负反馈互导放大器模块及相关双采样输出模块组成. 电路采用0.5 μm工艺制作完成. 通过合理设置电路中MOS管的参数和布局电流镜版图, 电路的非均匀性有了明显地改善. 通过测试, 电路的非均匀性小于1%, 器件总功耗约为100 mW, 并具有良好的低噪声特性, 输出噪声小于1 mV, 输出摆幅大于2 V. 该电路与160线列非制冷红外探测器互连后, 能较好地完成红外信号的读出, 在积分时间为20 μups的情况下, 器件的响应为0.294 mV/Ω, 整体性能良好. 该电路的研制对超长线列的非制冷红外冷探测器读出电路研制奠定了重要的技术基础.     

利用受激布里渊散射在光纤中实现光存储

利用有限差分法在慢变包络近似下求解了耦合波方程组,并从理论上实现了短光脉冲的存储。研究了数据脉冲的读出效率随声子寿命、布里渊增益系数、数据脉冲强度和控制脉冲强度的变化规律。结果显示:在长声子寿命的条件下,可以获得高的读出效率和长的存储时间,而布里渊增益系数和数据脉冲强度对读出效率没有影响;增大布里渊增益系数可以降低所需控制脉冲的强度。这种方法对短脉冲可以实现有效存储,而对长脉冲不能实现存储。     

Discriminating cosmic muons and X-rays based on rise time using a GEM detector

Gas electron multiplier(GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade.In this work,a triple GEM device with an effective readout area of 10 cm x10 cm is developed,and a method of discriminating between cosmic muons and X-rays based on rise time is tested.The energy resolution of the GEM detector is tested by ~(55)Fe ray source to prove the GEM detector has a good performance.Analysis of the complete signal-cycles allows us to get the rise time and pulse heights.The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold.     

Experiment on long-term readout of binarized image in photorefractive memory with double mutually pumped phase conjugators

We demonstrate long-term readout of a binarized image with a dynamic refreshment technique by mutually pumped phase conjugate mirrors (MPPCMs). Long-term continuous readout without any fixing technique can be achieved by the refreshment with image-bearing beam resonance between the phase conjugate mirrors. Our technique additionally offers image binarization by intensity thresholding of MPPCM without any external image processing systems. In this paper, we show grayscale-to-binary conversion as well as long-term readout can be realized by adjusting the appropriate incident beam intensities and the coupling strength of crystals. We perform recording and retrieving experiment with barium titanate crystals and demonstrate the binarized image can be reconstructed over 10 min in the double MPPCM configuration.     

High-frame-rate joint Fourier-transform correlator based on Sn(2)P(2)S(6) crystal

We present a joint Fourier-transform correlator working at a 10-kHz repetition rate. It is based on a photorefractive Sn(2)P(2)S(6) crystal operated in the pulsed direct band-to-band photoexcitation regime at a wavelength of 532 nm and a pulse length of 50 ns. The intersection of two plane waves with a total pulse fluence of 100muJ/cm(2) results in a buildup of thin dynamic holograms to a typical diffraction efficiency of 10(-4) in a time of ~1mus and decay again in less than 10mus . The correlator was tested by a fast image sequence generated by the pulsed readout of a holographic memory system. Successful correlation at a rate of 10 kHz has already been achieved for a pulse energy of only 200 nJ in the template images.     

Ultrahigh-sensitivity infrared detection system using an InGaAs p-i-n photodiode with low dielectric polarization noise

We developed a highly sensitive infrared photodetection system using an InGaAs p-i-n photodiode. The temperature and data sampling rate dependences of the readout noise were measured to determine the optimum temperature for low-noise detection. The optimum temperature for sampling rates below 100 Hz was 100 K, and the readout noise at 1 Hz was 2.5 e. The readout noise at 1 MHz and 140 K was 49.4 e. The light detection limit of the system was 8.2×10(-19) W at a wavelength of 1.3 μm. The spectral noise densities of a readout circuit were measured in order to determine the origin of noise.     

Linear collider flavour identification status report: Sensors for the international linear collider

The Linear Collider Flavour Identification (LCFI) collaboration is continuing the work to develop column-parallel CCDs (CPCCD) and CMOS readout chips to be used in the vertex detector at the international linear collider (ILC). The CPCCD achieves several orders of magnitude faster readout than conventional CCDs because every column is equipped with amplifier and ADC, enabling efficient data taking with low occupancy. Already two generations of CPCCDs and readout chips have been manufactured and the first chips have been fully tested. The second generation devices are now being evaluated. A new CCD-based device, the in-situ storage image sensor (ISIS) has also been developed. The ISIS offers numerous advantages in terms of relaxed readout, increased radiation hardness and great immunity to EMI. In this paper we present the results from the tests of the CPCCDs, readout chips and ISIS, as well as the plans for future developments. for the Linear Collider Flavour Identification (LCFI) Collaboration     

Experimental demonstration of a squeezing-enhanced power-recycled michelson interferometer for gravitational wave detection

Interferometric gravitational wave detectors are expected to be limited by shot noise at some frequencies. We experimentally demonstrate that a power recycled Michelson with squeezed light injected into the dark port can overcome this limit. An improvement in the signal-to-noise ratio of 2.3 dB is measured and locked stably for long periods of time. The configuration, control, and signal readout of our experiment are compatible with current gravitational wave detector designs. We consider the application of our system to long baseline interferometer designs such as LIGO.     

Study of a bulk-Micromegas with a resistive anode

The design and performance of a Micromegas with a resistive anode are presented in this paper. A thin resistive sheet with volume resistivity of 10¹² Ω·m cm is glued onto the readout electrode surface and its performance is investigated by using a ⁵⁵Fe X-ray radioactive source in the operation gas of argon and isobutene mixtures (Ar/Iso=95/5). The gas gain at different mesh high voltage, counting rate and working time are given. Energy spectra at different working voltages are measured and the results are discussed. We have oberved that a Micromegas with a resistive anode can be operated at higer gain than a standard Micromegas without sparks.     

Three-dimensional optical storage in fused silica using modulated femtosecond pulses

Three-dimensional bitwise optical recording with a density of 500 Gb/cm3 in fused silica using a Ti:sapphire femtosecond laser modulated by binary digits is demonstrated. Laser pulses modulation is realized by modulating two circuits of trigger pulses signal which are used to control laser pulses trapping and switching out from cavity, respectively. Bits are optically readout in both a parallel reading (phase-contrast) and a serial reading (confocal-type) methods. The method for modulating laser pulses can also be used in all of pulsed laser systems which operate in cavity-dumping configuration.     

Dephasing of multiparticle Rydberg excitations for fast entanglement generation

An approach to fast entanglement generation based on Rydberg dephasing of collective excitations (spin waves) in large, optically thick atomic ensembles is proposed. Long-range 1/r(3) atomic interactions are induced by microwave mixing of opposite-parity Rydberg states. The required long coherence times are achieved via four-photon excitation and readout of long wavelength spin waves. The dephasing mechanism is shown to have favorable, approximately exponential, scaling for entanglement generation.     

Nonvolatile holographic storage in iron-doped lithium tantalate with continuous-wave laser light

Holograms have been recorded in congruent LiTaO(3):Fe with continuous-wave laser light by use of a two-step process. Blue gating light (lambda=488 nm) sensitizes the crystals for holographic recording with red light (lambda=660 nm) of a diode laser. Refractive-index changes of as much as 1.0x10(-5) are achieved for intensities of the red light of 1 W/cm(2) . The saturation values are proportional to the intensity of the writing light. Nondestructive readout with red light is possible, and the holograms remain erasable for blue light.     

Single-shot readout of electron spins in a semiconductor quantum dot

We report on a method for single-shot readout of spin states in a semiconductor quantum dot that is robust against charge noise and can be used even when the electron temperature exceeds the energy splitting between the states. The spin states are first correlated to different charge states using a spin dependence of the tunnel rates. A subsequent fast measurement of the charge on the dot then reveals the original spin state. The method is analyzed theoretically, and compared to a previously used method. We experimentally demonstrate the method by performing readout of the two-electron spin states, achieving a single-shot visibility of more than 80%. We find very long triplet-to-singlet relaxation times (up to several milliseconds), with a strong dependence on in-plane magnetic field.     

Application of phototransferred thermoluminescence (PTTL) for dose re-assessment in routine dosimetry using MTS-N (LiF:Mg,Ti) thermoluminescent detectors

Erasure of the thermoluminescence (TL) signal on detector readout is considered to be a disadvantage of TL dosimetry, as post-readout dose reassessment is then impossible in principle. A method of dose reassessment based on phototransferred thermoluminescence (PTTL) has been developed at the Institute of Nuclear Physics, Polish Academy of Sciences (IFJ PAN) and applied to MTS-N (LiF:Mg,Ti) detectors. We demonstrate the possibility of applying PTTL for dose reassessment in MTS-N TL detectors routinely applied in the dosimetric service at IFJ PAN. Readings of TL detectors exposed to relatively high doses by the customers of our dosimetry service can now be reassessed using our automatic readers. A major obstacle in applying the PTTL method at lower exposures is the presence of residual dose accumulated in LiF:Mg,Ti detectors after many field exposure and readout cycles. Since most of the TL detectors in our service have been already used for a long time (e.g. for over 10 years in the case of some detector batches), we find that our PTTL method of dose reassessment is possible only in detectors which had received doses exceeding 5 mSv.