# Juan José Gómez Cadenas
**Juan José Gómez Cadenas** is a Spanish experimental particle physicist, an Ikerbasque Research Professor at the Donostia International Physics Center (DIPC) and a linked CSIC doctor at the Institute of Corpuscular Physics (IFIC, the joint University of Valencia–CSIC center), best known as the founder and co-spokesperson of the [NEXT experiment](https://www.edgepedia.org/next-experiment), which searches for neutrinoless double beta decay in xenon-136 at the Canfranc Underground Laboratory (LSC)[1](https://www.ikerbasque.net/en/juan-jose-gomez-cadenas) • [2](https://webific.ific.uv.es/web/en/content/g%C3%B3mez-cadenas-juan-jos%C3%A9) • [3](https://orcid.org/0000-0002-8224-7714). He is also a science writer with five novels and two popular essays to his name[4](https://dipc.ehu.eus/en/science-society/new-paths-science/jjgc-en).
| Key fact | Detail |
|---|---|
| Current posts | Ikerbasque Research Professor at DIPC (since March 2018); Doctor Vinculado, CSIC, at IFIC; co-spokesperson of NEXT at LSC[1](https://www.ikerbasque.net/en/juan-jose-gomez-cadenas) • [2](https://webific.ific.uv.es/web/en/content/g%C3%B3mez-cadenas-juan-jos%C3%A9) |
| Career path | PhD 1986; SLAC postdoc 1986–1990 (Fulbright); CERN fellow and staff; UMass Amherst assistant professor; Valencia chair 2006; CSIC research professor for Canfranc underground physics[3](https://orcid.org/0000-0002-8224-7714) • [1](https://www.ikerbasque.net/en/juan-jose-gomez-cadenas) |
| Signature work | Founded the NEXT collaboration in 2007; high-pressure xenon TPC for neutrinoless double beta decay of 136Xe[3](https://orcid.org/0000-0002-8224-7714) |
| Honors | Co-recipient of the 2016 Breakthrough Prize in Fundamental Physics (K2K and T2K collaborations); Distinguished CSIC scientist 2016; ERC Advanced Grant (2013)[1](https://www.ikerbasque.net/en/juan-jose-gomez-cadenas) • [3](https://orcid.org/0000-0002-8224-7714) |
| Writing | Five novels, two popular essays; *El Ecologista Nuclear* (Espasa, 2010); directs the science section of Jot Down[4](https://dipc.ehu.eus/en/science-society/new-paths-science/jjgc-en) • [5](https://www.foronuclear.org/valores-del-sector/voces-destacadas/juan-jose-gomez-cadenas/) |
## Education and career
Gómez Cadenas earned his doctorate in 1986 and spent 1986 to 1990 in postdoctoral research at the Stanford Linear Accelerator Center (SLAC) on a Fulbright fellowship, followed by a postdoctoral position at the Santa Cruz Institute for Particle Physics (SCIPP)[3](https://orcid.org/0000-0002-8224-7714) • [1](https://www.ikerbasque.net/en/juan-jose-gomez-cadenas). In September 1990 he joined the CERN scientific staff, first as a fellow and then as a research physicist[3](https://orcid.org/0000-0002-8224-7714).
**Neutrino oscillations.** From 1994 he worked on neutrino oscillation physics in the CERN NOMAD experiment, where he was analysis coordinator and directed the NOMAD-STAR project[3](https://orcid.org/0000-0002-8224-7714). His neutrino work continued in the Japanese–US K2K and T2K programs, which studied neutrino oscillations and earned the collaborating physicists, including him, a share of the 2016 [Breakthrough Prize in Fundamental Physics](https://www.edgepedia.org/breakthrough-prize-in-fundamental-physics)[1](https://www.ikerbasque.net/en/juan-jose-gomez-cadenas) • [6](https://www.imoh.eu/speakers/juan-jose-gomez-cadenas/). He was an assistant professor at the [University of Massachusetts](https://www.edgepedia.org/university-of-massachusetts) at Amherst[1](https://www.ikerbasque.net/en/juan-jose-gomez-cadenas).
**Return to Spain.** In 2006 he was appointed Catedrático of Atomic and Nuclear Physics at the University of Valencia, and in June of that year took a CSIC research professorship with a commitment to developing underground physics at Canfranc[3](https://orcid.org/0000-0002-8224-7714). Since March 2018 he has been affiliated with the Donostia International Physics Center as an Ikerbasque Research Professor[3](https://orcid.org/0000-0002-8224-7714) • [1](https://www.ikerbasque.net/en/juan-jose-gomez-cadenas). INSPIRE lists his experiments as NEXT, FNAL-E-0954, and DUNE[7](https://inspirehep.net/authors/1014784).
## The NEXT experiment
In 2007 Gómez Cadenas formed the NEXT collaboration (Neutrino [Experiment](https://www.edgepedia.org/experiment) with a Xenon TPC); he proposed the experiment to the LSC in 2008 and is co-spokesperson, together with Dave Nygren, the inventor of the time projection chamber[3](https://orcid.org/0000-0002-8224-7714) • [8](https://www.appec.org/interview-with-juan-jose-gomez-cadenas/). NEXT seeks to observe neutrinoless double beta decay of 136Xe using high-pressure xenon gas enriched in that isotope, at the Laboratorio Subterráneo de Canfranc in Spain[3](https://orcid.org/0000-0002-8224-7714) • [9](https://ar5iv.labs.arxiv.org/html/2201.10907).
**How the detector works.** A NEXT detector is a high-pressure xenon time projection chamber with two distinguishing features[9](https://ar5iv.labs.arxiv.org/html/2201.10907):
1. **Electroluminescent amplification.** [Ionization](https://www.edgepedia.org/ionization) electrons from the decay are drifted into an electroluminescence region where the signal is amplified, yielding an energy resolution better than 1% FWHM, measured at 0.5% FWHM at the decay energy for point-like particles and better than 1% for long tracks[9](https://ar5iv.labs.arxiv.org/html/2201.10907) • [8](https://www.appec.org/interview-with-juan-jose-gomez-cadenas/). Gaseous xenon gives about 10 times better energy resolution for the decay electrons than liquid xenon[10](https://cern-courier.web.cern.ch/a/the-incurable-attraction-of-physics/).
2. **Tracking.** Two photodetector planes record the light: one instrumented with photomultiplier tubes for calorimetry and one with silicon photomultipliers (SiPMs) that image the electron track, providing a topological signature that helps distinguish the two-electron signal from single-electron background events[11](https://beta.iopscience.iop.org/article/10.1088/1742-6596/1342/1/012046/pdf) • [9](https://ar5iv.labs.arxiv.org/html/2201.10907).
A third, longer-term feature is barium tagging: detecting the Ba2+ daughter ion left after the decay would identify signal events directly. The collaboration demonstrated identification of the Ba2+ ion in work published in Nature in 2020[5](https://www.foronuclear.org/valores-del-sector/voces-destacadas/juan-jose-gomez-cadenas/).
The NEXT-White demonstrator, holding 5 kg of xenon, took stable data from autumn 2016 to summer 2021, validating the technology and measuring the two-neutrino double beta decay mode; its energy resolution reached 0.91% at 2.6 MeV[9](https://ar5iv.labs.arxiv.org/html/2201.10907).
## Why neutrinoless double beta decay matters
Its detection would imply that the neutrino is a Majorana particle, identical to its own antiparticle, and that total lepton number is not conserved[9](https://ar5iv.labs.arxiv.org/html/2201.10907).
The scale of the challenge follows from the neutrino mass ordering: exploring the inverted hierarchy requires large masses, on the order of a ton of isotope, and background levels of very few counts per tonne-year[12](https://ar5iv.labs.arxiv.org/html/1301.2966). The next generation of experiments targets half-lives of 10²⁷ years, requiring tonne-scale detectors with backgrounds below 1 event per tonne per year in the region of interest[13](https://iopscience.iop.org/article/10.1088/1742-6596/1468/1/012227/pdf).
## By the numbers
**NEXT-White** ran with a fiducial mass of 3.50 ± 0.01 kg of 136Xe-enriched xenon, combining 271.6 days of enriched and 208.9 days of depleted data. It achieved 1% FWHM energy resolution at 2.6 MeV and set 90% C.L. lower limits on the neutrinoless half-life in the range 5.5 × 10²³ to 1.3 × 10²⁴ years, depending on the analysis method[14](https://link.springer.com/article/10.1007/JHEP09(2023)190).
**NEXT-100** is designed to hold about 70.5 kg of 136Xe at 13.5 bar in the active volume[15](https://link.springer.com/article/10.1140/epjc/s10052-025-14951-y). Its projected performance is a background rate of at most 4 × 10⁻⁴ counts keV⁻¹ kg⁻¹ yr⁻¹, energy resolution better than 1% FWHM at the 136Xe Q value, and a half-life sensitivity of 2.8 × 10²⁵ years (90% CL) for a 100 kg·year exposure, or 6.0 × 10²⁵ years after 3 effective years of running[16](https://www.osti.gov/biblio/1353390). The design aim is sensitivity of order 10²⁵ years at 90% C.L. with a background index below 1 × 10⁻³ counts/(keV·kg·year)[15](https://link.springer.com/article/10.1140/epjc/s10052-025-14951-y).
**Measured performance.** In commissioning, NEXT-100 began operation with xenon at 4 bar in October 2024; first 83mKr calibrations gave 4.37% FWHM at 41.5 keV, improving to 4.16% FWHM in a fiducial region representing 10 bar operation[17](https://arxiv.science/abs/2511.01710). With a Th-228 source the detector demonstrated an energy resolution of (0.90 ± 0.02)% FWHM at the Tl-208 photopeak of 2615 keV, extrapolating to (0.93 ± 0.02)% at the double beta decay end-point[18](https://arxiv.science/abs/2511.02467).
## How NEXT compares with rival experiments
Energy resolution is NEXT's distinguishing claim. A comparison of 0νββ experiments lists NEXT-100 at 0.7% FWHM against EXO-200 at 3.9%, and KamLAND-Zen at 9.9%[12](https://ar5iv.labs.arxiv.org/html/1301.2966). The pioneer gaseous TPC of the 1990s, at St. Gotthard, achieved 7% FWHM at the decay energy; NEXT is currently the only high-resolution xenon experiment searching for neutrinoless double beta decay[8](https://www.appec.org/interview-with-juan-jose-gomez-cadenas/).
NEXT-White's limit of 1.3 × 10²⁴ years is far shorter, reflecting its 3.5 kg fiducial mass[14](https://link.springer.com/article/10.1007/JHEP09(2023)190). Looking ahead, [nEXO](https://www.edgepedia.org/nexo), the next phase of EXO-200 using 5000 kg of enriched liquid xenon, projects a half-life sensitivity of 1.35 × 10²⁸ years at 90% CL in 10 years of data taking, covering the inverted mass ordering parameter space[19](https://arxiv.org/html/2504.03548) • [20](https://arxiv.science/abs/2106.16243). NEXT's strategy is to trade lower isotope mass for near-background-free, high-resolution detection, with barium tagging as the route to a truly background-free experiment[13](https://iopscience.iop.org/article/10.1088/1742-6596/1468/1/012227/pdf).
## Outreach and publications
Alongside his research, Gómez Cadenas has published five novels and two popular essays, and directs the scientific section of the online magazine Jot Down[4](https://dipc.ehu.eus/en/science-society/new-paths-science/jjgc-en). In 2010 he published the outreach book *El Ecologista Nuclear* (Espasa)[5](https://www.foronuclear.org/valores-del-sector/voces-destacadas/juan-jose-gomez-cadenas/). The Canfranc laboratory has published an interview with him titled "Podríamos usar los neutrinos para buscar petróleo", in which he also sketches speculative future scenarios[21](https://lsc-canfranc.es/entrevista-j-j-cadenas-podriamos-usar-los-neutrinos-para-buscar-petroleo/).
## References
1. [Juan José Gómez Cadenas, Ikerbasque researcher profile](https://www.ikerbasque.net/en/juan-jose-gomez-cadenas)
2. [Gómez Cadenas, Juan José, IFIC staff page](https://webific.ific.uv.es/web/en/content/g%C3%B3mez-cadenas-juan-jos%C3%A9)
3. [Juan Jose Gomez Cadenas (0000-0002-8224-7714), ORCID](https://orcid.org/0000-0002-8224-7714)
4. [Everything you always wanted to know about the universe but never dared to ask, DIPC](https://dipc.ehu.eus/en/science-society/new-paths-science/jjgc-en)
5. [Juan José Gómez Cadenas, Foro Nuclear interview](https://www.foronuclear.org/valores-del-sector/voces-destacadas/juan-jose-gomez-cadenas/)
6. [Juan José Gómez Cadenas, IMOH speaker page](https://www.imoh.eu/speakers/juan-jose-gomez-cadenas/)
7. [Juan Jose Gómez Cadenas, INSPIRE](https://inspirehep.net/authors/1014784)
8. [Interview with Juan Jose Gomez-Cadenas, APPEC](https://www.appec.org/interview-with-juan-jose-gomez-cadenas/)
9. [Status of the NEXT experiment for neutrinoless double beta decay searches (arXiv)](https://ar5iv.labs.arxiv.org/html/2201.10907)
10. [The incurable attraction of physics, CERN Courier](https://cern-courier.web.cern.ch/a/the-incurable-attraction-of-physics/)
11. [The NEXT experiment for neutrinoless double beta decay, J. Phys. Conf. Ser.](https://beta.iopscience.iop.org/article/10.1088/1742-6596/1342/1/012046/pdf)
12. [Status and physics potential of NEXT-100 (arXiv)](https://ar5iv.labs.arxiv.org/html/1301.2966)
13. [The search for Majorana neutrinos with a background-free gaseous Xenon TPC at the tonne scale, IOP](https://iopscience.iop.org/article/10.1088/1742-6596/1468/1/012227/pdf)
14. [Demonstration of neutrinoless double beta decay searches in gaseous xenon with NEXT, JHEP (2023)](https://link.springer.com/article/10.1007/JHEP09(2023)190)
15. [The NEXT-100 Detector, European Physical Journal C (2025)](https://link.springer.com/article/10.1140/epjc/s10052-025-14951-y)
16. [Sensitivity of NEXT-100 to neutrinoless double beta decay, OSTI.GOV](https://www.osti.gov/biblio/1353390)
17. [First results of the NEXT-100 detector using 83mKr decays (arXiv)](https://arxiv.science/abs/2511.01710)
18. [Demonstration of Sub-Percent Energy Resolution in the NEXT-100 Detector (arXiv)](https://arxiv.science/abs/2511.02467)
19. [Calculation and comparison of sensitivities in 0νββ experiments based on key parameters (arXiv, 2025)](https://arxiv.org/html/2504.03548)
20. [NEXO: Neutrinoless double beta decay search beyond 10^28 year half-life sensitivity (arXiv)](https://arxiv.science/abs/2106.16243)
21. [Entrevista J. J. Cadenas: 'Podríamos usar los neutrinos para buscar petróleo', LSC Canfranc](https://lsc-canfranc.es/entrevista-j-j-cadenas-podriamos-usar-los-neutrinos-para-buscar-petroleo/)
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*Topic: Encyclopedia › Physical world and mathematics › Physical and mathematical scientists › Physicists and astronomers › Experimental particle physicists › Neutrino and weak-interaction experimentalists*
*Initially written Oct 10, 2026 · Edited: Oct 11, 2026; Oct 15, 2026; Oct 21, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license