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arxiv: 2501.08554 · v3 · submitted 2025-01-15 · ⚛️ physics.ins-det · hep-ex· nucl-ex

In-situ high voltage generation with Cockcroft-Walton multiplier for xenon gas time projection chamber

Shinichi Akiyama , Junya Hikida , Masashi Yoshida , Kazuhiro Nakamura , Sei Ban , Masanori Hirose , Atsuko K. Ichikawa , Yoshihisa Iwashita
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Tatsuya Kikawa Yasuhiro Nakajima Kiseki D. Nakamura Tsuyoshi Nakaya Shuhei Obara Ken Sakashita Hiroyuki Sekiya Bungo Sugashima Soki Urano Sota Hatsumi Sota Kobayashi Hayato Sasaki
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Pith reviewed 2026-05-23 05:41 UTC · model grok-4.3

classification ⚛️ physics.ins-det hep-exnucl-ex
keywords Cockcroft-Walton multiplierxenon TPChigh voltage generationenergy resolutionneutrinoless double beta decaySiPM readoutin-situ voltage supply
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The pith

A Cockcroft-Walton multiplier placed inside a xenon gas TPC generates the high voltage needed for electron drift from a low external AC input.

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

The paper demonstrates that a Cockcroft-Walton multiplier can be integrated directly into the pressure vessel of a high-pressure xenon gas time projection chamber. This in-situ high-voltage generation avoids the need for a dedicated high-voltage feedthrough from outside the vessel. The approach was tested in the AXEL detector, which uses silicon photomultipliers for electroluminescence readout in a search for neutrinoless double beta decay. Successful operation over 40 days at 6.8 bar produced an energy resolution of 0.67 percent FWHM at 2615 keV. This shows the multiplier can supply the required field without compromising detector performance.

Core claim

The central discovery is that integrating a Cockcroft-Walton multiplier inside the pressure vessel of the AXEL xenon TPC allows in-situ generation of the high voltage for the drift field. A low AC voltage is supplied from outside and converted to the necessary DC high voltage inside, enabling continuous operation for 40 days at 6.8 bar while achieving an energy resolution of (0.67 ± 0.08)% FWHM at 2615 keV using SiPM-based electroluminescence readout.

What carries the argument

The Cockcroft-Walton multiplier, which steps up a low AC input voltage to a high DC output voltage inside the sealed pressure vessel to create the uniform electric field for drifting ionization electrons.

If this is right

  • The design eliminates the requirement for a high-voltage feedthrough penetrating the pressure vessel.
  • The TPC can be operated stably for extended periods without performance degradation from the internal voltage generator.
  • High energy resolution is maintained, supporting sensitive searches for rare events such as neutrinoless double beta decay.
  • The method is compatible with SiPM readout systems that are resistant to electronic noise.

Where Pith is reading between the lines

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

  • This in-situ generation technique might simplify scaling up larger xenon TPCs by reducing external connections.
  • It could be adapted to other gas detectors where high voltages are needed but feedthroughs pose challenges.
  • Further tests could explore higher pressures or different gas mixtures to broaden applicability.

Load-bearing premise

The internal placement of the Cockcroft-Walton multiplier does not introduce electronic noise or interference that would degrade the silicon photomultiplier electroluminescence signals.

What would settle it

Measurement showing that the energy resolution worsens when the multiplier is active compared to when high voltage is supplied externally.

Figures

Figures reproduced from arXiv: 2501.08554 by Atsuko K. Ichikawa, Bungo Sugashima, Hayato Sasaki, Hiroyuki Sekiya, Junya Hikida, Kazuhiro Nakamura, Ken Sakashita, Kiseki D. Nakamura, Masanori Hirose, Masashi Yoshida, Sei Ban, Shinichi Akiyama, Shuhei Obara, Soki Urano, Sota Hatsumi, Sota Kobayashi, Tatsuya Kikawa, Tsuyoshi Nakaya, Yasuhiro Nakajima, Yoshihisa Iwashita.

Figure 1
Figure 1. Figure 1: Schematic view of the AXEL 180 L prototype detector. [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Schematic cross-sectional view of the ELCC. [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: A picture of an ELCC unit without the anode electrode. One cell of the perimeter is [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Schematic cross-sectional view of the ELCC structures. The two-layer structure of [PITH_FULL_IMAGE:figures/full_fig_p007_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Schematic diagram of the CW multiplier. 3 Design and performance of the Cockcroft-Walton multiplier 3.1 Size and outgassing constraints The schematic diagram of the CW multiplier is shown in [PITH_FULL_IMAGE:figures/full_fig_p008_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: CW multiplier and resistor chain board implemented as a flexible printed circuit. [PITH_FULL_IMAGE:figures/full_fig_p009_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Schematic diagram (left) and a picture (right) of the measurement of the CW [PITH_FULL_IMAGE:figures/full_fig_p010_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: CW output voltages as a function of input frequency for 800 V peak-to-peak input [PITH_FULL_IMAGE:figures/full_fig_p010_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: Schematic diagram of the HV supply to the 180 L prototype detector [PITH_FULL_IMAGE:figures/full_fig_p012_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: CW and resistor chain are mounted on a PTFE jig and installed on the field cage. [PITH_FULL_IMAGE:figures/full_fig_p013_10.png] view at source ↗
Figure 11
Figure 11. Figure 11: Example waveform of an ELCC channel without hits. Sampling rate is [PITH_FULL_IMAGE:figures/full_fig_p014_11.png] view at source ↗
Figure 12
Figure 12. Figure 12: Distribution of the standard deviation of the baseline of the ELCC channels. [PITH_FULL_IMAGE:figures/full_fig_p014_12.png] view at source ↗
Figure 13
Figure 13. Figure 13: Installation of 1 kg (left) and 2 kg (right) of thorium-doped tungsten rods on the [PITH_FULL_IMAGE:figures/full_fig_p015_13.png] view at source ↗
Figure 14
Figure 14. Figure 14: Configuration of veto channels. The blue-shaded channels were assigned to veto. [PITH_FULL_IMAGE:figures/full_fig_p016_14.png] view at source ↗
Figure 15
Figure 15. Figure 15: Trends of the gas conditions (upper), and high voltages (lower). The gray-shaded [PITH_FULL_IMAGE:figures/full_fig_p017_15.png] view at source ↗
Figure 16
Figure 16. Figure 16: Trend of the CW output voltage (top), anode current (middle), and anode voltage [PITH_FULL_IMAGE:figures/full_fig_p018_16.png] view at source ↗
Figure 17
Figure 17. Figure 17: Distribution of the time intervals between scintillation and the end of the ELCC [PITH_FULL_IMAGE:figures/full_fig_p019_17.png] view at source ↗
Figure 18
Figure 18. Figure 18: Temporal variation of the photon count of xenon K [PITH_FULL_IMAGE:figures/full_fig_p020_18.png] view at source ↗
Figure 20
Figure 20. Figure 20: Photon counts vs. CSS of the photopeak of 911 keV gamma rays from [PITH_FULL_IMAGE:figures/full_fig_p023_20.png] view at source ↗
Figure 21
Figure 21. Figure 21: Photon count spectrum after applying all corrections and cuts. The drop in the [PITH_FULL_IMAGE:figures/full_fig_p024_21.png] view at source ↗
Figure 22
Figure 22. Figure 22: Interpolation of the energy resolution to the Q value. [PITH_FULL_IMAGE:figures/full_fig_p025_22.png] view at source ↗
Figure 23
Figure 23. Figure 23: A sample track of 2615 keV event. In the 3D plot, the size of the points is proportional [PITH_FULL_IMAGE:figures/full_fig_p026_23.png] view at source ↗
Figure 24
Figure 24. Figure 24: A sample track of 1593 keV event. In the 3D plot, the size of the points is proportional [PITH_FULL_IMAGE:figures/full_fig_p027_24.png] view at source ↗
read the original abstract

We have newly developed a Cockcroft-Walton (CW) multiplier that can be used in a gas time projection chamber (TPC). A TPC requires a high voltage to form an electric field that drifts ionization electrons. Supplying the high voltage from outside the pressure vessel requires a dedicated high-voltage feedthrough. An alternative approach is to generate the high voltage inside the pressure vessel with a relatively low voltage introduced from outside. A CW multiplier can convert a low AC voltage input to a high DC voltage output, making it suitable for this purpose. We have integrated a CW multiplier into the AXEL (A Xenon ElectroLuminescence detector), a high pressure xenon gas TPC to search for neutrinoless double beta decay of $^{136}$Xe. It uses silicon photomultipliers to detect the ionization electrons through elecrtoluminescence, making it strong against electronic noise. Operation of the CW multiplier was successfully demonstrated; the TPC was operated for 40 days at 6.8 bar, and an energy resolution as high as (0.67 $\pm$ 0.08) % (FWHM) at 2615 keV was obtained.

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.

Referee Report

1 major / 1 minor

Summary. The manuscript describes the development and integration of a Cockcroft-Walton (CW) multiplier inside the pressure vessel of the AXEL high-pressure xenon gas TPC to generate the drift field from a low external AC voltage, avoiding a dedicated HV feedthrough. The authors report successful demonstration of CW operation, stable TPC running for 40 days at 6.8 bar, and an energy resolution of (0.67 ± 0.08)% FWHM at 2615 keV obtained with SiPM-based electroluminescence readout.

Significance. If the quoted resolution was measured with the internal CW multiplier active, the result would establish a viable in-vessel HV generation technique compatible with low-noise SiPM readout, which is relevant for scaling xenon TPCs in neutrinoless double-beta-decay searches. The 40-day run provides evidence of operational stability.

major comments (1)
  1. [Abstract] Abstract: The text states that CW operation was successfully demonstrated and then reports the 40-day TPC operation plus the (0.67 ± 0.08)% resolution without explicitly confirming that the resolution datum was acquired while the CW multiplier was supplying the drift field. This linkage is required to substantiate the claim that internal placement introduces no measurable electronic noise or interference to the SiPM readout.
minor comments (1)
  1. [Abstract] Abstract: 'elecrtoluminescence' is a typographical error and should read 'electroluminescence'.

Simulated Author's Rebuttal

1 responses · 0 unresolved

We thank the referee for their review and for highlighting the need for explicit linkage in the abstract between the CW multiplier operation and the reported energy resolution. We address the comment below.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The text states that CW operation was successfully demonstrated and then reports the 40-day TPC operation plus the (0.67 ± 0.08)% resolution without explicitly confirming that the resolution datum was acquired while the CW multiplier was supplying the drift field. This linkage is required to substantiate the claim that internal placement introduces no measurable electronic noise or interference to the SiPM readout.

    Authors: We agree that the abstract as written does not explicitly state that the quoted energy resolution was acquired while the internal CW multiplier was active and supplying the drift field. The manuscript body describes the 40-day run with the CW in operation and presents the resolution result in that context, but the abstract requires clarification to make the connection unambiguous. In the revised version we will update the abstract to read: 'Operation of the CW multiplier was successfully demonstrated; the TPC was operated for 40 days at 6.8 bar with the CW supplying the drift field, and an energy resolution as high as (0.67 ± 0.08)% (FWHM) at 2615 keV was obtained.' This revision directly addresses the referee's concern without altering any numerical results. revision: yes

Circularity Check

0 steps flagged

No circularity: pure experimental demonstration with measured performance metrics

full rationale

The paper reports hardware development and direct experimental operation of a TPC with an internal CW multiplier over 40 days, including a measured energy resolution of (0.67 ± 0.08)% FWHM at 2615 keV. No derivation chain, equations, fitted parameters presented as predictions, or self-citations of uniqueness theorems appear in the provided text. The central claims rest on observed run data and resolution, which are independent of any internal reduction to inputs by construction.

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 theoretical modeling or new postulated objects.

pith-pipeline@v0.9.0 · 5835 in / 1029 out tokens · 32956 ms · 2026-05-23T05:41:11.494852+00:00 · methodology

discussion (0)

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Reference graph

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