arxiv: 2604.25609 · v1 · submitted 2026-04-28 · ⚛️ physics.ins-det · hep-ex

Recognition: unknown

A radon emanation measurement system at the Carleton Noble Liquid Detector Laboratory

P. Adhikari , M. G. Boulay , R. Crampton , D. Gallacher , M. Perry

Authors on Pith no claims yet

Pith reviewed 2026-05-07 13:57 UTC · model grok-4.3

classification ⚛️ physics.ins-det hep-ex

keywords radon emanationnoble liquid detectorslow-background experimentsdark matter searchesneutrino experimentsDEAP-3600ZnS(Ag) detector

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The pith

The COLD lab has built and calibrated a radon emanation measurement system for use in low-background rare-event experiments.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper describes the construction, calibration, and initial use of a radon detection setup at the Carleton Noble Liquid Detector Laboratory. The apparatus includes a stainless steel emanation chamber, a low-background ZnS(Ag) scintillation cell, and a transfer assembly that allows measurement of radon released from materials under vacuum. The same system was applied to quantify radon in nitrogen gas, in a gas filter from the DEAP-3600 processing system, and in the glove box used for assembling detector components. A reader would care because radon from natural uranium is one of the dominant backgrounds that limit sensitivity in dark matter and neutrino searches, and a calibrated diagnostic tool directly helps select cleaner materials and monitor clean-room conditions.

Core claim

The authors have developed, calibrated, and placed into service a complete radon emanation counter consisting of an emanation chamber, ZnS(Ag) detector, and transfer lines. The system has been used to measure radon release from test materials under vacuum, to assay residual radon in nitrogen and in the DEAP-3600 gas filter, and to calculate the radon concentration inside the glove box where critical DEAP-3600 components were assembled. The paper states that the now-calibrated counter functions as an essential diagnostic tool for reducing backgrounds in future rate-event search experiments.

What carries the argument

The radon emanation measurement system: a stainless steel emanation chamber coupled to a low-background ZnS(Ag) cell via a transfer and collection assembly, which isolates and counts radon atoms released from test materials or gases.

If this is right

Detector materials can be screened before assembly to select those with the lowest radon release rates.
Nitrogen gas supplies and filters can be monitored to keep radon contamination below experiment thresholds.
Radon levels in clean assembly environments such as glove boxes can be quantified and controlled.
Background budgets for dark matter and neutrino detectors can incorporate direct emanation data rather than estimates.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

The calibrated system could be applied to other noble-liquid experiments that face similar radon backgrounds.
Repeated measurements on the same materials over time would reveal whether emanation rates change with exposure or aging.
The glove-box and gas-filter results provide a concrete benchmark that other groups could use to validate their own radon control methods.

Load-bearing premise

The emanation chamber, transfer lines, and collection system introduce negligible extra radon or radon loss, so the measured rates reflect only the test materials.

What would settle it

A side-by-side comparison in which the system reports a radon rate from a known low-emanation sample that differs from an independent reference measurement by more than the combined uncertainties.

Figures

Figures reproduced from arXiv: 2604.25609 by D. Gallacher, M. G. Boulay, M. Perry, P. Adhikari, R. Crampton.

**Figure 1.** Figure 1: Radon Emanation chamber and gas handling system (left) and optional gas counting adapter (right) view at source ↗

**Figure 2.** Figure 2: Left: Photo of one Lucas cell prepared at the COLD lab, used for Radon measurements. Right: Labelled crosssection illustration of a Lucas cell, highlighting the coated area for scintillator. a) Open all valves except for valves from the chamber and pump the radon board for at least 2 hours. b) Isolate the secondary trap, by closing a valve between primary and secondary trap, and connect the Lucas cell to … view at source ↗

**Figure 3.** Figure 3: Schematic of DAQ system for Radon emanation setup at Carleton. PMT signals are amplified by the CAEN pre-amplifier, and digitized by the DT5780SCM, with automatic pulse-height analysis firmware. Data is recorded by the DAQ PC running ComPASS software for subsequent analysis. 3. Measurement: a) Remove the Lucas cell from the apparatus, cap the Lucas cell, then place in the counting slot on the PMT. b) Run t… view at source ↗

**Figure 4.** Figure 4: Alpha energy spectrum from the Buna gasket sample 1500 ADC counts. Before taking sample measurements, it is essential to determine both the background and efficiency of the detection system. Two primary sources of background are identified. The first originates from intrinsic activity within the Lucas cell, primarily due to radioactivity in the ZnS scintillation powder and the presence of 210Po deposited o… view at source ↗

**Figure 5.** Figure 5: Comparison of the alpha energy spectra obtained from the Buna gasket sample. The black curve represents the spectrum from the initial extraction, while the red curve corresponds to the second extraction. The gas extracted from both the chamber and the primary trap is recovered at 100% efficiency. Therefore, the observed 11% reduction in overall efficiency is primarily attributed to the shared volume betwee… view at source ↗

**Figure 6.** Figure 6: Radon emanation rates were measured for the two butyl gloves used in the glove box. Early measurements were excluded from the analysis, as they reflect radon outgassing from inter-particle spaces within the material, leading to elevated rates. The later data points, representing the steady-state emanation, were used to determine the radon emanation rate of the material view at source ↗

read the original abstract

Radon is one of the most important sources of background in rare event search experiments, such as those searching for Dark Matter and neutrinos, due to its unavoidable production from natural uranium. In low-background experiments, radon emanation from detector materials and components accounts for a major portion of contamination. To investigate this, a radon detection system was developed at the Carleton nOble Liquid Detector Laboratory (COLD Lab). The setup consists of a stainless steel emanation chamber, a low-background ZnS(Ag) cell, and an assembly for radon transfer and collection. This setup was used to study radon emanation from materials under vacuum conditions. Additionally, a charcoal trap made of activated charcoal and equipped with a flow meter was constructed to study radon levels in nitrogen gas and the residual radon in the gas filter used in the DEAP-3600 processing system. The radon concentration in the glove box, where critical DEAP-3600 internal detector components were completed, was also calculated based on these measurements. Now calibrated and in-use, the COLD lab radon emanation counter is an essential diagnostic tool for reducing backgrounds in future rate-event search experiments.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

This is a straightforward lab report on a radon emanation counter built for DEAP-3600 that describes the hardware but skips the blank runs and efficiency numbers needed to make the results trustworthy.

read the letter

The paper walks through the construction of a stainless-steel emanation chamber, ZnS(Ag) counter, transfer lines, and charcoal trap at the COLD lab, then shows how they used it on DEAP-3600 materials, nitrogen gas, the gas filter, and the glove box. That is the core of what they did. The hardware choices are sensible for low-background work and the applications are directly tied to their experiment, which gives it some practical value for groups doing similar noble-liquid detector work. They also mention that the system is now calibrated and in use, which at least signals they have moved past the design stage. Those parts are fine as far as they go. The real gap is exactly what the stress-test flagged. The text gives no blank-chamber rates, no upper limits on system emanation, no measured transfer or collection efficiencies, and no uncertainty breakdown. Without those, any quoted emanation rate from a sample could include contributions from the chamber walls, lines, or trap, and there is no way to judge how much. The claim that this is now an essential diagnostic tool therefore rests on an untested assumption that the apparatus itself is clean. That is a standard requirement in this subfield and it is missing here. The paper is aimed at other low-background experimentalists who might copy the layout or need a reference for similar monitoring. It is not bringing new methods or results that would interest a broader audience. I would send it for peer review in an instrumentation journal like JINST, but only after the authors add the missing blank data, efficiencies, and error budgets; without those it is too thin to stand on its own.

Referee Report

3 major / 2 minor

Summary. The manuscript describes the design, construction, and initial use of a radon emanation measurement system at the Carleton nOble Liquid Detector (COLD) Laboratory. The apparatus comprises a stainless-steel emanation chamber, a low-background ZnS(Ag) scintillation cell, a vacuum transfer and collection assembly, and a separate activated-charcoal trap with flow meter for assaying radon in nitrogen gas and in the DEAP-3600 gas filter. The system was employed to measure emanation rates from materials under vacuum and to estimate radon concentrations in the DEAP-3600 glove box. The authors state that the counter is now calibrated and in use as an essential diagnostic for background reduction in future rare-event searches.

Significance. If the missing quantitative validation were supplied, the work would constitute a useful technical contribution to material screening for low-background noble-liquid detectors. The hardware choices (stainless-steel chamber, ZnS(Ag) cell, charcoal trap) are conventional and appropriate for the stated purpose; however, the present manuscript supplies no calibration constants, efficiencies, or background limits, so the claimed utility remains unsupported.

major comments (3)

[Abstract, §3] Abstract and §3 (system description): the statement that the system is “now calibrated” is not accompanied by any reported calibration procedure, standard source, measured efficiency, or uncertainty. Without these data the central claim that the counter is a reliable diagnostic tool cannot be evaluated.
[§2, §4] §2 (emanation chamber and transfer lines) and §4 (applications): no blank-chamber count rates, upper limits on apparatus self-emanation, or measured transfer/recovery efficiencies are presented. The skeptic’s concern is therefore unaddressed: any non-zero background or loss directly scales into all quoted rates and prevents isolation of test-material contributions.
[§4] §4 (DEAP-3600 and glove-box results): the manuscript reports that radon concentrations “were also calculated” but supplies neither the raw count rates, the conversion factors used, nor an error budget. This omission makes the numerical claims impossible to assess or reproduce.

minor comments (2)

Figure captions and text should explicitly state the live time, pressure, and temperature conditions for each measurement run.
The manuscript would benefit from a short table summarizing the key hardware parameters (chamber volume, cell efficiency if known, charcoal mass, flow range).

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their careful reading of the manuscript and for the constructive comments that help strengthen the presentation of our work. We address each major comment below and have revised the manuscript to supply the requested quantitative details.

read point-by-point responses

Referee: [Abstract, §3] Abstract and §3 (system description): the statement that the system is “now calibrated” is not accompanied by any reported calibration procedure, standard source, measured efficiency, or uncertainty. Without these data the central claim that the counter is a reliable diagnostic tool cannot be evaluated.

Authors: We agree that the original manuscript did not provide sufficient detail on the calibration. In the revised version we have added a dedicated subsection in §3 that describes the calibration procedure, the standard radon source employed, the measured efficiency of the ZnS(Ag) cell, and the associated uncertainties. These additions directly support the claim that the counter is now a calibrated diagnostic tool. revision: yes
Referee: [§2, §4] §2 (emanation chamber and transfer lines) and §4 (applications): no blank-chamber count rates, upper limits on apparatus self-emanation, or measured transfer/recovery efficiencies are presented. The skeptic’s concern is therefore unaddressed: any non-zero background or loss directly scales into all quoted rates and prevents isolation of test-material contributions.

Authors: We acknowledge that background and efficiency data were omitted. The revised manuscript now reports blank-chamber count rates and upper limits on apparatus self-emanation in §2. Measured transfer and recovery efficiencies, obtained from dedicated tests, are presented with uncertainties in §4 so that material contributions can be properly isolated. revision: yes
Referee: [§4] §4 (DEAP-3600 and glove-box results): the manuscript reports that radon concentrations “were also calculated” but supplies neither the raw count rates, the conversion factors used, nor an error budget. This omission makes the numerical claims impossible to assess or reproduce.

Authors: We have expanded §4 to include the raw count rates, the conversion factors derived from calibration, and a complete error budget for the calculated radon concentrations in the DEAP-3600 glove box and gas filter. These additions allow the numerical results to be assessed and reproduced. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental hardware description with no derivations or predictions

full rationale

The paper is a straightforward description of building, calibrating, and using a radon emanation measurement system consisting of a stainless-steel chamber, ZnS(Ag) cell, transfer lines, and charcoal trap. No equations, fits, predictions, or first-principles derivations appear in the abstract or described content. The central claim that the system is 'now calibrated and in-use' as an essential diagnostic tool rests on the experimental setup itself rather than any self-referential reduction, self-citation chain, or renaming of inputs as outputs. Unquantified blank rates or transfer efficiencies (noted in the skeptic attack) are matters of experimental completeness and potential systematic uncertainty, not circularity in any claimed derivation chain. This is the expected honest non-finding for a pure instrumentation paper.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

No free parameters, axioms, or invented entities; the paper is an experimental instrumentation report without mathematical models or new theoretical constructs.

pith-pipeline@v0.9.0 · 5515 in / 1075 out tokens · 71706 ms · 2026-05-07T13:57:04.216280+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

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