arxiv: 2604.23216 · v1 · submitted 2026-04-25 · 🌌 astro-ph.IM

Recognition: unknown

Successful irradiation campaign on PRIMA/PRIMAger KIDs detectors with DRACuLA

Valentin Sauvage , Ana\"is Besnard , Giulia Conenna , Kenichi Karatsu , Stephen J.C. Yates , Lorenza Ferrari , Bruno Maffei

Authors on Pith no claims yet

Pith reviewed 2026-05-08 07:09 UTC · model grok-4.3

classification 🌌 astro-ph.IM

keywords kinetic inductance detectorscryogenic irradiationproton beam testingdilution refrigeratorradiation hardnesssub-Kelvin detectorsspace instrumentation

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The pith

A mobile cryogenic platform maintained KID detectors at 120 mK throughout a 12-hour proton irradiation.

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

This paper reports the design and successful operation of a mobile dilution refrigerator platform for irradiating sub-Kelvin detectors while they remain at their operating temperature. The detectors stayed at 120 millikelvin for the full twelve hours of exposure to 184 MeV protons. Such testing matters for space-borne instruments because radiation effects on detectors can depend strongly on temperature, and prior methods often could not replicate the cold operating conditions during beam exposure. The campaign confirms that the platform integrates with a beam line and delivers the required stability without temperature excursions or interference.

Core claim

The central result is that the DRACuLA mobile dilution refrigerator platform successfully kept PRIMA/PRIMAger KID detector arrays at 120 mK during a continuous 12-hour run of 184 MeV proton irradiation after integration with the beam line at the test facility. This establishes that the system can expose detectors to particle beams at their nominal sub-300 mK operating temperatures.

What carries the argument

DRACuLA, the mobile dilution refrigerator platform developed to expose sub-Kelvin detectors to particle beams while maintaining their operating temperature.

If this is right

Detectors for astrophysics missions can be irradiated under conditions that closely match their space environment.
The 12-hour stability at 120 mK shows the platform is ready for extended radiation exposure studies.
Beam-line integration of the mobile system allows flexible use at different accelerator facilities.
The approach separates the engineering validation of the irradiation setup from the scientific results on detector performance reported separately.

Where Pith is reading between the lines

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

The same mobile platform could be adapted for testing other cryogenic detector technologies such as transition-edge sensors or quantum devices.
Conducting irradiations at operating temperature may reveal temperature-dependent annealing or damage mechanisms not visible in room-temperature tests.
Repeated campaigns with varying proton fluences could quantify the radiation tolerance limits of KID arrays more accurately.

Load-bearing premise

The mobile platform and its beam-line integration would maintain stable temperature control at 120 mK with no unaccounted interference over the entire 12-hour irradiation period.

What would settle it

Observation of any temperature rise above 120 mK or unexpected fluctuations in the detector temperature readings during the proton exposure would falsify the claim of successful stable operation.

Figures

Figures reproduced from arXiv: 2604.23216 by Ana\"is Besnard, Bruno Maffei, Giulia Conenna, Kenichi Karatsu, Lorenza Ferrari, Stephen J.C. Yates, Valentin Sauvage.

**Figure 1.** Figure 1: FIG. 1. CAD view of the experimental setup (Device under test view at source ↗

**Figure 3.** Figure 3: FIG. 3. DRACuLA in front of the proton beam line with the colli view at source ↗

**Figure 2.** Figure 2: FIG. 2. The cryostat mounted on its support frame in front of the view at source ↗

**Figure 5.** Figure 5: FIG. 5. Cooling power at the 120 mK stage over a 4-hour win view at source ↗

**Figure 6.** Figure 6: FIG. 6. Temperature of the 1 K stage before (BEAM OFF) and view at source ↗

**Figure 7.** Figure 7: FIG. 7. Discrete Fourier Transform of the 1 K stage temperature view at source ↗

read the original abstract

DRACuLA (Detector irRAdiation Cryogenic faciLity for Astrophysics) is a mobile dilution refrigerator platform developed at the Institut d'Astrophysique Spatiale (IAS) to expose sub-Kelvin detectors to particle beams at their nominal operating temperature, in the range 50-300 mK. We report on its design, beam-line integration at the Particle Therapy Research Center (PARTREC) in Groningen, and the operational performance achieved during the September 2025 irradiation campaign on Kinetic Inductance Detector (KID) arrays developed by SRON for the PRIMA mission. The detector samples were maintained at 120 mK throughout a 12-hour proton irradiation run at 184 MeV. The scientific results of this campaign are reported in the companion paper by Besnard et al.

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

DRACuLA is a working mobile dilution refrigerator that kept PRIMA KIDs at 120 mK through a 12-hour 184 MeV proton run, but the paper is thin on actual performance numbers.

read the letter

DRACuLA is a working mobile dilution refrigerator that kept PRIMA KIDs at 120 mK through a 12-hour 184 MeV proton run, but the paper is thin on actual performance numbers. The main new element is the platform itself: a transportable dilution fridge built at IAS to let sub-Kelvin detectors see particle beams at their operating temperature. They moved it to PARTREC, lined it up with the beam, and completed the irradiation without the system failing. That is a practical step for anyone who needs radiation testing on flight-like detectors for missions such as PRIMA. The design description and the integration steps are straightforward, and the fact that temperature held for the full run is the central operational result. The companion paper is supposed to carry the detector physics, so this one stays focused on the facility. The soft spots are straightforward. The text gives no plots of base temperature versus time, no measured beam-induced heat load, no stability numbers, and no error analysis. The claim that the detectors stayed at 120 mK rests on a single statement rather than data that a reader could check. Without those details the paper reads more like a successful test report than a methods paper that others can build on. It is aimed at instrumentation teams who design or qualify cryogenic detectors for space. Someone planning their own beam test would pick up useful notes on how the mobile setup was coupled to the line, even if they still need more numbers. The logic is consistent and the result does not contradict itself. I would send it for peer review rather than desk reject, mainly so the authors can add the missing temperature and stability data before it goes into the literature.

Referee Report

1 major / 2 minor

Summary. The manuscript reports the development of the DRACuLA mobile dilution refrigerator for irradiating sub-Kelvin KID detectors at their operating temperature. It details the platform's design, its integration with the beam line at the Particle Therapy Research Center (PARTREC), and the operational achievement of maintaining PRIMA/PRIMAger KID detector samples at 120 mK during a full 12-hour proton irradiation at 184 MeV. The scientific interpretation of the irradiation effects on the detectors is presented in a companion paper by Besnard et al.

Significance. If the reported performance is substantiated, this platform represents an important advancement in cryogenic instrumentation for astrophysics, enabling direct testing of detector response to particle radiation at base temperatures without the need for thermal cycling. This is particularly relevant for missions like PRIMA that require robust performance in space radiation environments. The successful beam-line integration highlights the practicality of mobile cryogenic systems for such experiments.

major comments (1)

[Operational Performance] The central claim of maintaining the detectors at a stable 120 mK base temperature throughout the 12-hour irradiation lacks any quantitative supporting evidence, such as temperature time-series data, stability metrics (e.g., RMS fluctuation), or error analysis. This information is essential to substantiate the 'successful' nature of the campaign and should be included to allow readers to assess the performance.

minor comments (2)

[Abstract] The abstract mentions 'September 2025' for the campaign; ensure the date is accurate and consistent with the main text.
Include a schematic or photo of the mobile platform and beam-line setup to aid reader understanding of the integration.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their positive assessment of the manuscript and for the constructive comment on operational performance. We address the point below.

read point-by-point responses

Referee: [Operational Performance] The central claim of maintaining the detectors at a stable 120 mK base temperature throughout the 12-hour irradiation lacks any quantitative supporting evidence, such as temperature time-series data, stability metrics (e.g., RMS fluctuation), or error analysis. This information is essential to substantiate the 'successful' nature of the campaign and should be included to allow readers to assess the performance.

Authors: We agree that quantitative evidence is required to substantiate the central claim. In the revised manuscript we will add a new figure showing the temperature time-series recorded over the full 12-hour irradiation, together with text reporting the RMS temperature fluctuation and any associated error analysis. These additions will allow readers to evaluate the stability at 120 mK. revision: yes

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper is a purely descriptive experimental report on the DRACuLA platform's design, beam-line integration, and performance during a 12-hour proton irradiation campaign. It contains no equations, derivations, fitted parameters, predictions, or load-bearing self-citations. The central claim of stable 120 mK operation is presented as an achieved empirical outcome with no internal reduction to inputs by construction, making the manuscript self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

No mathematical derivations, free parameters, axioms, or invented physical entities are involved; this is an experimental instrumentation report.

pith-pipeline@v0.9.0 · 5463 in / 963 out tokens · 65261 ms · 2026-05-08T07:09:43.995368+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

3 extracted references · 1 canonical work pages

[1]

Alignment Mechanical alignment of DRACuLA with the beam line was achieved using a supplementary support frame that raises the cryostat to 1.5 m height, where the beam axis is located, as shown in Fig. 2. A laser placed along the nominal beam axis served as an alignment reference to position the cryostat windows accurately with respect to the beam (Fig. 3)...
[2]

Magnetic shielding is provided by a combination of Niobium and CryoPerm enclosures surround- ing the sample holder

Experimental Setup The device under test (DUT) is enclosed in a light-tight box to prevent stray photons from reaching the detectors dur- ing dark measurements. Magnetic shielding is provided by a combination of Niobium and CryoPerm enclosures surround- ing the sample holder. During the 2025 campaign, both the absorber-coupled and antenna-coupled KID arra...

2025
[3]

Zanardi and L

Thermal Performance During Irradiation Temperature stability at the detector level was monitored by a Lakeshore 372 AC resistance bridge reading a RuO 2 ther- mometer calibrated down to 30 mK, installed at the 120 mK thermal link. A 120Ωresistive heater mounted directly on the cold plate provided the heating power for the PID controller (see note 13). Pri...

work page doi:10.1103/phys- 2025