Replaceable getter container in the detector system

Abstract

The design of the getter container is characterized in that it is a half-cylinder with a cylindrical recess that allows the precise assembly of two getter containers around the copper cooling finger of the ATC cryostat.

Description

Introduction:

[0001] The invention aims to minimize maintenance and repair times with open cryostats by relocating the getter reservoir to a suitable, free and accessible space within the cryostat, with close contact with the cold finger. This allows for easy replacement of the zeolite reservoir during regular maintenance or repairs. This must be taken into account during cryostat design. Description:

[0002] Operating large gamma spectrometer arrays like AGATA makes operating costs a crucial factor for the efficient use of approved research funds. For this reason, maintenance times, whether regular or due to downtime, should be as short as possible. Furthermore, the work should be manageable by personnel with basic training and no specialized training required.

[0003] It is not possible to maintain a sufficient number of backup detector systems as a replacement, as this is uneconomical due to the high investment costs and the long production times of the highly segmented germanium detectors.

[0004] The challenge is to reduce maintenance and repair times with open cryostats to a minimum and to simplify them significantly. State of the art before the inventive step:

[0005] Typical Ge detector cryostat systems on the market have a permanently mounted getter reservoir, usually in or on the Dewar or in the cold finger, which ensures a stable vacuum during detector operation. A saturated and thus unusable getter (usually zeolite) would have to be replaced, which is technically and time-consuming, or annealed at high temperatures (200 °C and above), which is not possible with built-in Ge detectors. The inventive step:

[0006] The inventive step lies in the design and relocation of the getter reservoir from a non-removable to an easily replaceable arrangement. During routine maintenance or repair of a detector system, the saturated zeolite can be replaced with the reservoir.

[0007] Simplifying the zeolite reservoir replacement procedure reduces maintenance or repair time, and a new zeolite reservoir increases vacuum stability during operation of complex experiments.

[0008] It is imperative to heat the zeolite-filled getter reservoir to 400°C before installation in a vacuum furnace. This ensures that no residual gases are bound to the zeolite. Technical area:

[0009] The invention relates to the design and arrangement of getter reservoirs in cryostat systems, in particular for shortening maintenance and repair times in spectrometers such as AGATA.

[0010] Advantages of the invention: • Cost savings through simplified maintenance and repair work • Easy replacement of the zeolite reservoir for laboratory staff • Improving the stability of the vacuum during experiments • Increased reliability of detector systems Industrial applicability:

[0011] The invention is applied in the production of any asymmetric AGATA triple cryostat and is commercially marketed. The invention is suitable for use in comparable cryostats for other applications. Summary:

[0012] The invention relates to the relocation of the getter reservoir in ATC cryostat systems to simplify maintenance and repair times and to increase the stability of the vacuum during complex and lengthy experiments. List of names: 1 copper cooling finger 2 getter containers 3 openings for gas exchange Terminology: ATC: Abbreviation for AGATA Triple Cryostat. The AGATA Triple Cryostat is the system that allows and enables the operation of exactly three highly segmented Ge detectors. The cryostat ensures the required high vacuum, mechanical precision in detector positioning, cooling to below -180 °C, and electrical readout of the total of 111 high-resolution signal outputs. Array: A detector array is a combination of many detectors that form a (closed) spherical shell, similar to a soccer ball. This is achieved with a certain number of hexagons and pentagons, which then form the front of the detectors. Dewar: The Dewar is a vacuum-insulated storage vessel for liquid nitrogen, similar to a thermos flask. For more complex detector systems that can be suspended flat or upside down in an array, so-called all-layer Dewars are used, whose internal construction prevents the liquid nitrogen from leaking out. LN2: Abbreviation for the English term "liquid nitrogen." The 2 stands for the fact that naturally occurring nitrogen is a double molecule. Getters: A getter is a chemically reactive material designed to maintain a vacuum for as long as possible. Gas molecules form a direct chemical or physical bond at the surface of the getter and are thereby removed from the volume. A standard getter, for example, is zeolite, an open-pore ceramic that, when cooled to liquid nitrogen temperature, is an effective getter. Grounding: English term for ground, or mass (electrical); ground is the reference level against which a measurement is made or a signal is generated. FET: Abbreviation for field-effect transistor, a semiconductor transistor with high sensitivity and low inherent noise while maintaining high gain. When cooled, the electronic performance of these components is particularly good. Ge detector: A detector system made of a high-purity germanium crystal. The Ge detector system is used to measure ionizing radiation. Cryostat: Device for cooling and maintaining a high vacuum for thermal and electrical isolation of the Ge detector systems installed in the cryostat.

Claims

[1] Construction of the getter container characterized by that it is a half cylinder with a cylindrical recess that allows the precise assembly of two getter containers around the copper cooling finger of the ATC cryostat. [2] Position of the getter container characterized by that the getter container is installed in the largest free volume of the ATC cryostat in order to enable the best exchange of the residual gases with the getter material (zeolite) and thus the condition of the residual gases.

Images