Detector - Revision history

KevinYager: /* See Also */

2020-09-01T18:20:59Z

‎See Also

KevinYager: /* Solid state pixel-array */

2016-05-18T16:22:23Z

‎Solid state pixel-array

KevinYager: /* X-ray Area Detectors */

2015-07-25T12:30:55Z

‎X-ray Area Detectors

KevinYager: /* Hybrid pixel-array */

2015-07-25T12:25:14Z

‎Hybrid pixel-array

KevinYager at 13:36, 22 April 2015

2015-04-22T13:36:19Z

KevinYager: /* Fiber-coupled CCD */

2015-01-24T14:56:21Z

‎Fiber-coupled CCD

KevinYager: /* Kinds of Area X-ray Detectors */

2015-01-12T17:58:09Z

‎Kinds of Area X-ray Detectors

KevinYager: /* Kinds of Area Detectors */

2015-01-12T17:54:38Z

‎Kinds of Area Detectors

KevinYager: /* Kinds of Area Detectors */

2014-12-20T16:15:19Z

‎Kinds of Area Detectors

KevinYager: Created page with "In x-ray and neutron scattering, the '''detector''' is the hardware that detects the scattered radiation. On modern beamlines, ''area'' detectors are used: i.e..."

2014-12-16T23:29:02Z

Created page with "In x-ray and neutron scattering, the '''detector''' is the hardware that detects the scattered radiation. On modern beamlines, ''area'' detectors are used: i.e..."

New page

In [[x-ray]] and [[neutron]] [[scattering]], the '''detector''' is the hardware that detects the scattered radiation. On modern [[beamlines]], ''area'' detectors are used: i.e. they generate two-dimensional (2D) images of scattering.

==Kinds of Area Detectors==
A variety of detector technologies are available.
===Fiber-coupled CCD===
This well-developed detector design uses a fluorescent or phosphorescent screen behind an opaque barrier (typically [[Be]], though amorphous [[carbon]] is also possible). A bundle of fiber-optics is then bonded to this screen. The fiber-bundle is 'tapered'; i.e. it has been drawn so that the bundle is wide on one end but much smaller on the other end. This bundle thus acts as a grid of light-pipes. X-rays are absorbed in the screen layer, and converted into visible-light photons. Then these photons travel down the fiber-bundle, and are detected using a charge-coupled device (CCD). The CCD chip is essentially just like the chip used in a digital camera (though it may have better performance: higher dynamic range, and lower noise owing to active cooling). This design is robust, and yields a wide area image with no gaps. However, the image may have some distortion, due to imperfects in the drawing of the bundle (especially near the edges of the image). Detector software typically applies an 'unwarping', but even with this correction, images may have some lingering distortion.
* Advantages:
** Robust and well-understood technology.
* Disadvantages:
** Somewhat slow readout.
** Moderate background noise.
* Examples:
** MarCCD

===Hybrid pixel-array===
TBD

* Advantages:
** Low noise.
** High dynamic range.
** Nearly photon-counting.
** Fast readout.
** Well-defined pixel positions.
* Disadvantages:
** Expensive.
** Images have gaps (intermodule gaps).
* Examples:
** Dectris Pilatus

===Image plates===
An image plate is a plate of photo-sensitive material. The plate is first 'cleared' and then loaded into the sample chamber in the desired position. During sample irradiation, the scattering radiation will 'develop' the plate. The plate must then be removed and loaded into a special scanner that 'reads' the accumulated dose. This reading is used to generate a digital file

* Advantages:
** Inexpensive
** Can easily create a custom shape (e.g. a through-hole).
* Disadvantages:
** Laborious and cumbersome to take data.
** Positional error in replacing plate introduces an error in data.

← Older revision		Revision as of 18:20, 1 September 2020
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	==See Also==		==See Also==
	* Takaki Hatsui and Heinz Graafsma [http://journals.iucr.org/m/issues/2015/03/00/cw5005/index.html X-ray imaging detectors for synchrotron and XFEL sources] ''IUCrJ'' '''2015''', 2 (3). [http://dx.doi.org/10.1107/S205225251500010X doi: 10.1107/S205225251500010X]		* Takaki Hatsui and Heinz Graafsma [http://journals.iucr.org/m/issues/2015/03/00/cw5005/index.html X-ray imaging detectors for synchrotron and XFEL sources] ''IUCrJ'' '''2015''', 2 (3). [http://dx.doi.org/10.1107/S205225251500010X doi: 10.1107/S205225251500010X]
		+	===Electron Detectors===
		+	* Direct Electron Detectors (DED) and Electron-Event Representation (EER): Danve, R. [https://journals.iucr.org/m/issues/2020/05/00/me6094/index.html Electrons receive individual treatment with electron-event representation] ''IUCrJ'' '''2020'''. [https://doi.org/10.1107/S2052252520011616 doi: 10.1107/S2052252520011616]

@@ Line 3: / Line 3: @@
 ==X-ray Area Detectors==
 A variety of detector technologies are available. Below are a few of the common types of detectors used on [[labscale]] [[x-ray]] instruments and [[synchrotron]] [[beamlines]]:
 ===Fiber-coupled CCD===
 This well-developed detector design uses a fluorescent or phosphorescent screen behind an opaque barrier (typically [[Be]], though amorphous [[carbon]] is also possible). A bundle of fiber-optics is then bonded to this screen. The fiber-bundle is 'tapered'; i.e. it has been drawn so that the bundle is wide on one end but much smaller on the other end. This bundle thus acts as a grid of light-pipes. X-rays are absorbed in the screen layer, and converted into visible-light photons. Then these photons travel down the fiber-bundle, and are detected using a charge-coupled device (CCD). The CCD chip is essentially just like the chip used in a digital camera (though it may have better performance: higher dynamic range, and lower noise owing to active cooling). This design is robust, and yields a wide area image with no gaps. However, the image may have some distortion, due to imperfects in the drawing of the bundle (especially near the edges of the image). Detector software typically applies an 'unwarping', but even with this correction, images may have some lingering distortion.

@@ Line 14: / Line 14: @@
 ** MarCCD
-===Hybrid pixel-array===
+===Solid state pixel-array===
-This newer technology involves a two-dimensional array of photon-counting pixels. X-ray photons are directly detected in silicon electronics: each pixel has its own amplifier, discriminator, and counter. By setting the threshold to ~1/2 the energy of the x-ray radiation being used, background noise is very efficiently excluded. This low noise-floor, coupled to a large per-pixel counter size, allows these detectors to have exceptionally large dynamic range.
+Many newer detector technologies are being developed based on solid state (CMOS) pixels. This newer technology involves a two-dimensional array of photon-counting pixels. X-ray photons are directly detected in silicon electronics: each pixel has its own amplifier, discriminator, and counter. By setting the threshold to ~1/2 the energy of the x-ray radiation being used, background noise is very efficiently excluded. This low noise-floor, coupled to a large per-pixel counter size, allows these detectors to have exceptionally large dynamic range.
 * Advantages:

← Older revision		Revision as of 13:36, 22 April 2015
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	===Avalanche Photodiode (APD)===		===Avalanche Photodiode (APD)===
	An [http://en.wikipedia.org/wiki/Avalanche_photodiode APD] is a semiconductor that converts photons to electrical current. Through the use of substantial gain, these diodes can detect extremely weak x-ray signals. They are typically used as point detectors for measuring beam flux; e.g. as a diagnostic. They can also be scanned in order to reconstruct one-dimensional data (e.g. for [[reflectivity]]). In some instruments, the beamstop is equipped with a diode, such that the direct-beam flux (after the sample) is measured (this can be used to assess absorption, total scattering power, etc.).		An [http://en.wikipedia.org/wiki/Avalanche_photodiode APD] is a semiconductor that converts photons to electrical current. Through the use of substantial gain, these diodes can detect extremely weak x-ray signals. They are typically used as point detectors for measuring beam flux; e.g. as a diagnostic. They can also be scanned in order to reconstruct one-dimensional data (e.g. for [[reflectivity]]). In some instruments, the beamstop is equipped with a diode, such that the direct-beam flux (after the sample) is measured (this can be used to assess absorption, total scattering power, etc.).
		+
		+	==See Also==
		+	* Takaki Hatsui and Heinz Graafsma [http://journals.iucr.org/m/issues/2015/03/00/cw5005/index.html X-ray imaging detectors for synchrotron and XFEL sources] ''IUCrJ'' '''2015''', 2 (3). [http://dx.doi.org/10.1107/S205225251500010X doi: 10.1107/S205225251500010X]

@@ Line 1: / Line 1: @@
 In [[x-ray]] and [[neutron]] [[scattering]], the '''detector''' is the hardware that detects the scattered radiation. On modern [[beamlines]], ''area'' detectors are used: i.e. they generate two-dimensional (2D) images of scattering.
-==Kinds of Area X-ray Detectors==
+==X-ray Area Detectors==
 A variety of detector technologies are available. Below are a few of the common types of detectors used on [[labscale]] [[x-ray]] instruments and [[synchrotron]] [[beamlines]]:
 ===Fiber-coupled CCD===
@@ Line 37: / Line 37: @@
 ** Laborious and cumbersome to take data.
 ** Positional error in replacing plate introduces an error in data.

@@ Line 36: / Line 36: @@
 * Examples:
 ** Dectris Pilatus
 ===Image plates===

@@ Line 10: / Line 10: @@
 ** Somewhat slow readout.
 ** Moderate background noise.
 * Examples:
 ** MarCCD