Microanalysis surface studies and photoemission properties of CsI photocathodes

Almeida, J.; Braem, A.; Breskin, A.; Chechik, R.; Cohen, Sidney R.; Coluzza, C.; Conforto, Egle; Margaritondo, G.; Nappi, E.; Paić, G.; Piuz, F.; dell’Orto, Tiziana; Scognetti, T.; Sgobba, S.; Tonner, B. P.

doi:10.1016/0168-9002(95)00574-9

Cited by 24 publications

(9 citation statements)

References 7 publications

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“…In our previous study [11] we have already shown that heating of the CsI photocathodes not only increases their UV and soft X-ray sensitivity (as reported by Breskin et al [8], [15] and Lees et al [16]), but also substantially improves the stability of their response under UV exposure. In the present work we elaborate on the aging of CsI and KBr photocathodes and consider the importance of radiation wavelength, flux rate, and angle of incidence for the QE degradation.…”

Section: Sensitivity Degradation Under Uv Irradiationmentioning

confidence: 70%

UV radiation resistance and solar blindness of CsI and KBr photocathodes

Tremsin¹,

Siegmund

2001

IEEE Trans. Nucl. Sci.

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A detailed study of the stability of CsI and KBr photocathodes under UV irradiation is presented. UV quantum efficiency degradation was found to be more pronounced at lower illumination intensity for the same accumulated dose and illumination wavelength. For an equal number of extracted photoelectrons in-band UV exposure led to a larger sensitivity decay as compared to out-of-band illumination. The angle of radiation incidence was not important for the UV sensitivity degradation, while changes of visible light rejection (i.e., degradation of solar blindness) did depend on the incidence angle: the photocathodes illuminated at normal incidence were activated much faster than the films irradiated at grazing angle. We found that the increase of visible sensitivity can be characterized by the total accumulated dose and is independent of irradiation flux during UV activation. We also observed that heat annealing substantially improves the visible light rejection of C-sI photocathodes.

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Section: Sensitivity Degradation Under Uv Irradiationmentioning

confidence: 70%

UV radiation resistance and solar blindness of CsI and KBr photocathodes

Tremsin¹,

Siegmund

2001

IEEE Trans. Nucl. Sci.

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“…Hoedlmoser 等 [23] 认为, 薄膜中水分子的存在降低了 CsI 的扩散激活能, 使得扩散加速, 从而使颗粒长大, 笔者进一步认为水在颗粒间界的"短路扩散"效应在颗粒的生长中起了重要作用 [49] 。对于极端潮湿空气中 CsI 薄膜表面变为乳白色的原因, Tremsin 等 [48] 认为是 CsI 颗粒团聚以及大量基底暴露所造成, Xie 等 [6] 认为可能是 CsOH 溶解于水中所造成。刚制备的 CsI 薄膜光阴极的 QE 并不理想, 经真空退火处理后, QE 有一定程度的上升并能减缓在空气中的老化, 对于有限度暴露空气造成的 QE 下降, 也可通过真空退火进行恢复, 而在极端潮湿环境中造成的 QE 下降却不可能恢复 [52] 。尽管研究众多, 但人们对于真空退火法的原理还存在争议。Boutboul 等 [53] 的实验结果表明退火并未增加 CsI 薄膜中二次电子的逃逸长度, 认为 QE 的上升源于薄膜表面电子的发射性能的增强, 另一些研究者 [34,54] 认为电子传输性质的改变也应考虑在内。Hoedlmoser 等 [23] 认为退火导致的 QE 上升是 CsI 薄膜结构变化与脱水共同作用的结果: 刚制备的 CsI 薄膜中含有水分 (即使在 10 -5 Pa 的真空度下), 真空退火使水分从薄膜内部扩散到表面并挥发, 在这个过程中薄膜结构发生了变化(颗粒长大), 表面吸附的水分也被除去。而 Buzulutskov 等 [12][13][14][15][16][17][18][19][20][21][22] [55] 。一些研究发现, 在热蒸发时给基底加上负的偏压, 能够制备出更不容易受潮的 CsI 光阴极, 原因为薄膜表面有更多的 I -离子, 倾向与水分子中 OH 共价键的 H 端形成偶极层, 使电子亲和势下降 [37,43] 。有研究表明相比于慢的蒸发速率, 较快的蒸发速率制备的 CsI 薄膜更不容易受潮, 但并未给出明确的解释 [56][57]…”

Section: 老化研究unclassified

Recent Progress in Research on CsI Thin Film Photocathodes

Fan¹,

Li²,

Chen³

et al. 2015

Journal of Inorganic Materials

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Caesium iodide (CsI) thin films have attracted much attention due to good electron transport and emission properties in the soft X-ray and extreme ultraviolet range. With the rapid development of nuclear physics, high energy physics and astrophysics, the requirements for CsI film photocathodes become increasingly severe, and it is therefore of considerable interest to develop CsI photocathodes with high quantum efficiency (QE) and stable performance. However, the internal mechanisms of QE variation and photocathode aging are not entirely clear or certain up to date. In this paper, the recent progress on CsI film photocathodes is reviewed and some controversial issues are introduced. Several perspectives are also proposed in the end.

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“…As MCP requires an ultra low vacuum atmosphere to operate properly, a two stage pump (rotary and turbo pump) is used to evacuate the vacuum flanges in which the X-ray sensor is placed. In Figure 4b, a thick layer of Cesium Iodide (CsI) was deposited onto the MCP which acts as a photocathode to convert the incoming X-ray to UV (305 nm) which the MCP has a much higher efficiency to (Anderson et al 1992;Almeida et al 1995;Breskin 1996). Directly applying a layer of CsI on the MCP simplifies the structure of the X-ray module and a fine spatial resolution can be achieved by controlling its thickness at the expense of Xray attenuation efficiency which is less crucial in our application.…”

Section: Description Of the Mcp Based X-ray Sensormentioning

confidence: 99%

Development of a Fast and High Resolution X-Ray Imaging Sensor for In-Line Inspection of Tape Substrate

Yeom¹,

Roh²,

Jung³

et al. 2010

International Journal of Optomechatronics

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In an automated tape substrate inspections, machine vision is widely adopted for high throughput and cost advantages. However, conventional methods are overly sensitive to foreign particles or have limitations in detecting three-dimensional defects such as top over-etched defect. Foreign particles such as dustsdo not affect the integrity of the final product and are often detected as defects during inspection. To complement vision inspection systems, a prototype fast and fine spatial resolution X-ray imaging sensor has been developed. This image sensor, based on an optoelectronic devicethe microchannel plate (MCP), has a spatial resolution of 20 m and functions at frame rate of 30 fps. X-ray imaging is appropriate as it is virtually transparent to dust particles and provides information regarding the thickness of the copper wire patterns.

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Microanalysis surface studies and photoemission properties of CsI photocathodes

Cited by 24 publications

References 7 publications

UV radiation resistance and solar blindness of CsI and KBr photocathodes

UV radiation resistance and solar blindness of CsI and KBr photocathodes

Recent Progress in Research on CsI Thin Film Photocathodes

Development of a Fast and High Resolution X-Ray Imaging Sensor for In-Line Inspection of Tape Substrate

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