Revisiting Currie — how low can you go?

The low-background, VUV-sensitive 3-inch diameter photomultiplier tube R11410 has been developed by Hamamatsu for dark matter direct detection experiments using liquid xenon as the target material. We present the results from the joint effort between the XENON collaboration and the Hamamatsu company to produce a highly radiopure photosensor (version R11410-21) for the XENON1T dark matter experiment. After introducing the photosensor and its components, we show the methods and results of the radioactive contamination measurements of the individual 123 546 Page 2 of 10 Eur. Phys. J. C (2015) 75 :546 materials employed in the photomultiplier production. We then discuss the adopted strategies to reduce the radioactivity of the various PMT versions. Finally, we detail the results from screening 286 tubes with ultra-low background germanium detectors, as well as their implications for the expected electronic and nuclear recoil background of the XENON1T experiment.

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“…Upper limits are calculated as described in [33] and given at 90 % C.L. Further details about the analysis procedure can be found in [31].…”

Section: Germanium Spectroscopymentioning

confidence: 99%

Lowering the radioactivity of the photomultiplier tubes for the XENON1T dark matter experiment

Aprile¹,

Agostini²,

Alfonsi³

et al. 2015

Eur. Phys. J. C

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“…In order to treat correctly these cases we have referred to the procedure described in (Currie, 1968) and (Hurtgen, 2000). For each gamma peak in the measured spectrum we have calculated a decision-threshold (L c ) and a detection limit (L d ) defined in the following way:…”

Section: Gamma Spectrometrymentioning

confidence: 99%

U and Th content in the Central Apennines continental crust: A contribution to the determination of the geo-neutrinos flux at LNGS

Coltorti

Boraso

Mantovani

et al. 2011

Geochimica et Cosmochimica Acta

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“…Operationally, it leads to two concepts: the a priori "detection limit" L D and the a posteriori "critical level" L C [11]. The a priori detection limit, L D , made before counting the person, determines the minimum acquisition time needed to detect a given activity of a radionuclide [12,13]. The a posteriori critical level L C (or decision level), calculated after counting, evaluates the highest limit of the activity of a radionuclide that has not been clearly detected in a photopeak zone.…”

Section: Detector Efficiency and Limit Of Detection In Case Of Low Enmentioning

confidence: 99%

Direct Determination of Radionuclides in the Body Optimisation of Measurements Parameters and Results Analysis

Genicot¹,

Fonseca²,

Kramer³

et al. 2011

WJNST

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Whole body counting (WBC) benefits from new types of detectors and methodologies. It has found applications in areas such as in medicine, protection of workers and of population. The design of a WBC facility should be tailored to the type of application. Monte Carlo calculations help to improve the reliability of the calibration of a facility, particularly for non-standard measurements (child, etc.), help in optimizing shielding of counting rooms, preventing large systematic errors and lowering detection limits. In vivo counting may be used to evaluate the distribution of radionuclides in organs for metabolic studies with multiple detectors or with a scan of the body. Reduction of detection levels by background reduction is limited. Improved sensitivity can be obtained by adapting the detector type and size to the measured photon energy. The benefit of comparison exercises and training courses are demonstrated. Further improvements in accuracy can be expected from cooperative works with other techniques: indirect methods (urines and faeces) and passive detectors placed correctly on the body can in the case of high levels of contamination can be used to improve the burden assessment.

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Revisiting Currie — how low can you go?

Cited by 62 publications

References 2 publications

Lowering the radioactivity of the photomultiplier tubes for the XENON1T dark matter experiment

Lowering the radioactivity of the photomultiplier tubes for the XENON1T dark matter experiment

U and Th content in the Central Apennines continental crust: A contribution to the determination of the geo-neutrinos flux at LNGS

Direct Determination of Radionuclides in the Body Optimisation of Measurements Parameters and Results Analysis

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