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Detector Element
 

 

GEM High-Purity Germanium (HPGe) Coaxial Detectors (in PopTop Capsule)

For computer-based analysis of complex spectra requiring the best in resolution, peak-to-Compton ratio, peak shape, and efficiency:
  • Large stocklist at all times
  • Efficiencies to 150%, higher on request
  • New "Application-Tuned" PROFILE Series available
  • PopTop flexibility
  • Excellent energy resolution
  • Excellent peak symmetry
  • Automatic high-voltage shutdown protects preamplifier input FET
  • Indicator warns of excessive counting rate
  • PLUS preamplifier option for ultra-high-rate applications

 

GEM Series HPGe detectors are manufactured with ORTEC’s own HPGe (see Part A, Section A1.) and represent the state of the art in "conventional", i.e., outer contact Li diffusion and inner contact ion-implanted HPGe coaxial detectors (Fig.). Because of the superior quality of ORTEC’s HPGe material, GEM detectors feature the best available energy resolution, peak-to-Compton ratios, and peak symmetry ratios at 1.33 MeV. Note that energy resolution and symmetry ratios are warranted to two decimal places.

The high degree of symmetry resulting from the superior material and processes used in manufacturing ORTEC detectors make them ideal for computer-based analysis where the detector peak shape is of paramount importance.

ORTEC is renowned for delivering detectors with measured specifications substantially better than the warranted values.

The geometrical features of the GEM detector that result in such excellent peak shape are: (1) by far the world’s best germanium crystals, (2) deep holes used for making the central contact, (3) "bulletized" (rounded) front corners on the detector for uniform electric field. No one makes detectors as well as ORTEC.

 


Figure. Configurations of Coaxial Germanium Crystals.

 

 

ORTEC maintains a large stocklist of GEM detectors. Some of these have "super specifications," that is, a warranted energy resolution better than the first category GEM specifications.

Unless otherwise specified, each GEM HPGe coaxial detector is supplied in a PopTop capsule. A complete detector assembly requires a cryostat and a dewar

Options of Interest
  • PLUS preamplifier option for ultra-high-count-rate applications
  • Non-PopTop low-background versions of the GEM detector are available
  • X-COOLERoption for practical LN2-free cooling , SMART-1 "Intelligent" detector option

Ordering Information

GEM HPGe Coaxial Detector (Non-PopTop or PopTop)

For GEM Detector in PopTop capsule†, add "P4" to the model no. [e.g., GEM90P4]. FW.02M/FWHM specification is Typical, all other specifications are warranted.

 

Model No.

Efficiency (%)

Resolution

 

Peak-to-Compton Ratio

Peak Shape*

@ 122 keV (keV)

@ 1.33 MeV (keV)

FW.1M/ FWHM

FW.02M/**
FWHM

GEM150

150

1.30

2.3

90:1

2.0

3.1

GEM140

140

1.30

2.2

90:1

2.0

3.1

GEM130

130

1.30

2.1

90:1

2.0

3.1

GEM120

120

1.30

2.1

86:1

2.0

3.1

GEM110

110

1.30

2.1

85:1

2.0

3.0

GEM100

100

1.20

2.1

83:1

2.0

3.0

GEM90

90

1.20

2.0

80:1

2.0

3.0

GEM80

80

1.10

2.0

77:1

2.0

3.0

GEM75

75

1.10

2.0

77:1

2.0

3.0

GEM70

70

1.00

2.0

75:1

2.0

3.0

GEM65

65

1.00

1.95

73:1

1.9

3.0

GEM60

60

1.00

1.95

70:1

1.9

3.0

GEM55

55

1.00

1.90

67:1

1.9

2.8

GEM50

50

0.90

1.90

66:1

1.9

2.6

GEM45

45

0.90

1.90

64:1

1.9

2.6

GEM40

40

0.87

1.85

64:1

1.9

2.6

GEM35

35

0.85

1.85

62:1

1.9

2.6

GEM30

30

0.85

1.85

60:1

1.9

2.6

GEM25

25

0.82

1.85

56:1

1.9

2.6

GEM20

20

0.82

1.80

52:1

1.9

2.6

GEM15

15

0.82

1.80

46:1

1.9

2.6

GEM10

10

0.80

1.75

41:1

1.9

2.6

Options

 

 

 

 

 

 

-PLUS

Ultra-high-count-rate Preamplifier, add "-PLUS" to the model number [e.g., GEM10P4-PLUS for PopTop or GEM10-PLUS for Non-PopTop]

SMART-1-P

SMART-1 detector option for positive bias detector. To order, add SMART-1-P as a separate line item.

-PLB

Reduced background PopTop Capsule, add "-PLB" to the model number [e.g., GEM10P4-PLB]

 

†All GEM PopTop detector capsules include sealed detector element, preamplifier, and high-voltage filter. Useful energy ranges, from 40 keV to 10 MeV.

*FWHM = Full Width at Half Maximum; FW.1M = Full Width at One-Tenth Maximum; FW.02M = Full Width at One-Fiftieth Maximum; total system resolution for a source at 1000 counts/s measured in accordance with ANSI/IEEE Std. 325-1996, using ORTEC standard electronics.

**Typical Value.

NOTE: For those familiar with HPGe detector specifications, you will notice that ORTEC now offers ONLY "first category" detector specifications. Recent process improvements now make this possible.

 

 

 

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