Gammasphere Detectors: Difference between revisions

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'''''This image is clickable. Click text to go to the page for that item.'''''
<imagemap>
Image:DetectorLabeledUpdated.png|400px|thumb|center|An outlined detector of Gammasphere and its different parts.
poly 96 158 82 183 131 220 150 195 [[The Slope Box Extension]]
poly 156 198 133 228 245 306 253 297[[The Slope Box]]
poly 362 509 384 483 400 447 479 532 471 549 457 560 [[High Purity Germanium (HPGe) and BGO]]
poly 82 312 101 269 135 237 243 317 183 389 [[Liquid Nitrogen]]
poly 278 345 224 415 270 447 327 386 [[Preamplifier]]
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The detectors in [[Gammasphere]] are [[High Purity Germanium (HPGe)|high purity germanium]] detectors sensitive to x- and gamma-rays from a few dozen keV to ~10MeV energy.  All Gammasphere detectors are Compton shielded using bismuth germanate (BGO) shields.  Six planar BGO detectors form a hexagonal shield array around the HPGe detector sides and a 7th BGO shield behind (at farther radius from the interaction point) is used as a "back plug".  The germanium detector itself is of the coaxial type.  Incident gamma-rays typically deposit charge in the germanium that is read out through the center contact. A detector in the upgraded Gammasphere system consists of [[High Purity Germanium (HPGe) and BGO|Ge and BGO]], a [[preamplifier]], a [[Liquid Nitrogen|nitrogen tank]], a [[The Slope Box|slope box]], and an [[The Slope Box Extension|SBX]]. All the hardware is there to monitor or maintain the Ge and BGO. 
The data that is collected in each detector occurs when gamma rays hit the [[High Purity Germanium (HPGe) and BGO|Ge and BGO]] of the detector. Incident gamma-rays typically deposit charge in the germanium that is read out through the center contact, creating various [[Detector Signals|signals]]. The signal is understood and conditioned through the [[DAQ system]], the data acquisition system that presents human-readable results to the user. Detectors are the first components of Gammasphere to acquire any kind of data about gamma ray interaction. The data that is collected in each detector goes through the [[DAQ system]], the data acquisition system which presents results to the user. 


=== Segmented Detectors ===
Many of the Ge detectors in Gammasphere are segmented.  In these the Ge portion of the detector is split in half resulting in three Ge contacts (Center, Side A, Side B).  Only one of the side connections is brought out to the digitizers as the charge that would be in the other side is given by subtraction of the measured side from the center contact.
=== Non-Segmented Detectors ===
Non-Segmented detectors are the same as segmented ones, but the Ge inside of the detector isn't split, resulting in two Ge contacts instead of three. The hardware is nearly identical, and the main difference is in the signals that are sent.
==Detector EDM Screens==
Gammasphere Detectors have multiple relevant screens. The primary ones used are the temperature screens of the detector and the relevant process variables (PVs). The following image shows the [[Run Control Detector PVs|detector PVs screen]]. It is a clickable image that can show you what the different buttons show when clicked:
<imagemap>
<imagemap>
Image:SBX Array.jpg|frame|center|alt=Test Image Map
Image:PVsCrop.png|500px|center
rect 465 210 675 265 [[The Slope Box]]
rect 11 82 319 251 [[Run Control Detector PV Options]]
rect 10 291 424 356 [[Run Control Digitizer PV Screens]]
rect 13 386 331 416 [[Run Control Digitizer PV Screens]]
</imagemap>
</imagemap>


== Gammasphere detectors ==
The screen below shows the [[Run Control Temperatures|temperature monitoring screen]] of each detector:
 
The detectors in Gammasphere are high purity germanium detectors sensitive to x- and gamma-rays from a few dozen keV to ~10MeV energy.  All Gammasphere detectors are Compton shielded using bismuth germanate (BGO) shields.  Six planar BGO detectors form a hexagonal shield array around the HPGe detector sides and a 7th BGO shield behind (at farther radius from the interaction point) is used as a "back plug".  The germanium detector itself is of the coaxial type.  Incident gamma-rays typically deposit charge in the germanium that is read out through the center contact.


Should the gamma-ray scatter within the Ge portion of the detector the scatter will normally be detected by interaction with the BGO shields.  Thus we define a 'clean' event as one that excites the Ge but none of the surrounding BGO of a given detector and a 'dirty' event as one in which both the Ge and BGO light up.  Within the digitizing data acquisition system, the sum of all 7 BGO signals is applied to one digitizer channel and the Ge center contact is digitized by another channel in the same digitizer.  A discriminator threshold is applied to both signals and the Router trigger module looks at the time relationship between Ge discriminator bits and the associated BGO Sum discriminator bits.  If the two discriminator bits are close enough in time the event is marked as 'dirty'.


=== Segmented Detectors ===
[[File:Getempmon.png|700px|center]]


Many of the Ge detectors in Gammasphere are segmented.  In these the Ge portion of the detector is split in half resulting in three Ge contacts (Center, Side A, Side B).  Only one of the side connections is brought out to the digitizers as the charge that would be in the other side is given by subtraction of the measured side from the center contact.
''Go back to [[Digital Gammasphere Upgrade Project]]''

Latest revision as of 20:37, March 22, 2023

This image is clickable. Click text to go to the page for that item.

The Slope Box ExtensionThe Slope BoxHigh Purity Germanium (HPGe) and BGOLiquid NitrogenPreamplifier
An outlined detector of Gammasphere and its different parts.

The detectors in Gammasphere are high purity germanium detectors sensitive to x- and gamma-rays from a few dozen keV to ~10MeV energy. All Gammasphere detectors are Compton shielded using bismuth germanate (BGO) shields. Six planar BGO detectors form a hexagonal shield array around the HPGe detector sides and a 7th BGO shield behind (at farther radius from the interaction point) is used as a "back plug". The germanium detector itself is of the coaxial type. Incident gamma-rays typically deposit charge in the germanium that is read out through the center contact. A detector in the upgraded Gammasphere system consists of Ge and BGO, a preamplifier, a nitrogen tank, a slope box, and an SBX. All the hardware is there to monitor or maintain the Ge and BGO.

The data that is collected in each detector occurs when gamma rays hit the Ge and BGO of the detector. Incident gamma-rays typically deposit charge in the germanium that is read out through the center contact, creating various signals. The signal is understood and conditioned through the DAQ system, the data acquisition system that presents human-readable results to the user. Detectors are the first components of Gammasphere to acquire any kind of data about gamma ray interaction. The data that is collected in each detector goes through the DAQ system, the data acquisition system which presents results to the user.

Segmented Detectors

Many of the Ge detectors in Gammasphere are segmented. In these the Ge portion of the detector is split in half resulting in three Ge contacts (Center, Side A, Side B). Only one of the side connections is brought out to the digitizers as the charge that would be in the other side is given by subtraction of the measured side from the center contact.

Non-Segmented Detectors

Non-Segmented detectors are the same as segmented ones, but the Ge inside of the detector isn't split, resulting in two Ge contacts instead of three. The hardware is nearly identical, and the main difference is in the signals that are sent.

Detector EDM Screens

Gammasphere Detectors have multiple relevant screens. The primary ones used are the temperature screens of the detector and the relevant process variables (PVs). The following image shows the detector PVs screen. It is a clickable image that can show you what the different buttons show when clicked:

Run Control Detector PV OptionsRun Control Digitizer PV ScreensRun Control Digitizer PV ScreensPVsCrop.png
About this image

The screen below shows the temperature monitoring screen of each detector:


Getempmon.png

Go back to Digital Gammasphere Upgrade Project

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