Ultra Low-Background Cryostats
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Features
- Low background materials
- No-stream-path design
- Offset preamplifier and adsorber
- Standardized hardware
- Uncompromised reliability
Description
CANBERRA has years of experience in building custom low-background detectors for low level gamma spectroscopy. The most important features of these custom detectors have been incorporated into standardized cryostat designs which can be produced quickly and economically and which produce predictable results. There are two basic Ultra Low-Background cryostat designs available, a vertical dipstick and a U-style integral. Both have the following design and construction features in common:
- Low background materials are used for detector chamber, holder, and internal hardware.
- Design offsets are used to allow the use of shielding materials between the detector element and hotter materials such as the preamplifier and adsorber (molecular sieves).
- Direct streaming paths for external (to shield) sources of radiation are eliminated.
- Materials having high cross-section for cosmic neutrons are avoided in construction.
- Designs do not compromise ease of use or long-term reliability.
Among the select materials used in CANBERRA ULB cryostats are the following:
- Aluminum - 99.999% pure with guaranteed thorium and uranium less than 1 ppb.
- Copper - 99.99% pure (better than standard OFHC grade).
- Stainless Steel - selected low Co-60 content.
- Composite Carbon - Virtually zero background substitute for Be in low energy and wide range detectors.
A thorough discussion of low background detectors and systems can be found in CANBERRA’s “Ultra Low-Background Detector Systems” Application Note. Ordering information is given below:
| Model List for Ultra Low-Background Cryostat Option: | ||
| Cryostat Type | Dipstick | U-Style Integral |
| Cryostat Model | 7500SL | 7915-30 |
| Remote Detector Chamber |
RDC-X* | N.A. |
| *X = 2, 4, or 6 for 2 inch, 4 inch or 6 inch neck. | ||
Base model 7500 SL
| Material (Choose one of the following): | |
| Detector Type | Hardware Option |
| Standard Electrode Coax | ULB-GC |
| Reverse Electrode Coax | ULB-GR |
| Extended Range Coax | ULB-GX |
| Low Energy | ULB-GL |
| Well Detector | ULB-GW |
| Broad Energy | ULB-GB |
End cap dimensions depend on detector size. The chart below shows the typical efficiency range vs. end-cap diameter. End cap lengths are also greater for larger detectors. Consult the factory if end-cap size is critical in your application.
| Rel. Efficiency (%) | Diameter in. (Mm) |
| £40 | 3.0 (76) |
| 40-50 | 3.25 (83) |
| 50-70 | 3.50 (89) |
| 70-100 | 3.75 (95) |
| ³100 | 4.0 (102) |
Base Model 7915-30
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Note to our International Customers: If you would like a quote on this product, please contact your Local Sales Office for assistance. |
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| Models | Description | |
| 7915-30 | U-Type Integral Flanged Cryostat | |
| 7500SL | Vertical Dipstick Slimline Cryostat | |
| RDC-2 | Remote Detector Chamber 2" Neck | |
| RDC-4 | Remote Detector Chamber 4" Neck | |
| RDC-6 | Remote Detector Chamber 6" Neck | |
| ULB-GC | Hardware for Standard Electrode Coax Detector | |
| ULB-GL | Hardware for Low Energy Detector | |
| ULB-GR | Hardware for Reverse Electrode Coax Detector | |
| ULB-GW | Hardware for Well Detector | |
| ULB-GX | Hardware for Extended Range Coax Detector | |