Radon-induced backgrounds in the NEXT-100 experiment
Abstract
A bstract The NEXT-100 detector at the LSC aims at the first competitive search for the 0 νββ decay using a high-pressure 136 Xe electroluminescent time projection chamber. The first low-background run of NEXT-100 at 3.95 bar has been devoted to the measurement of the radon-induced backgrounds impacting this search. The contributions from both the internal and external airborne radon have been evaluated. The internal 222 Rn activity is found to be (0.95 ± 0.04(stat) ± 0.09(sys)) Bq/m 3 , while no traces of 220 Rn have been observed. Most of the 222 Rn progeny plate-out on the surface of the cathode of the detector, leading to a rate of Rn-induced 214 Bi of (0.97 ± 0.05(stat) ± 0.10(sys)) Hz for visible energies above 400 keV. The corresponding background index in the 0 νββ region of interest is evaluated as (7.3 ± 1.5(stat) ± 0.8(sys)) × 10 − 4 counts/(keV · kg · yr) after selection of the fully contained events. This background index is reduced to ∼ 4 × 10 − 5 counts/(keV · kg · yr) by applying a topological selection requiring only one double-electron-like track in the events. This value is one order of magnitude below the total radiogenic background expectation in NEXT-100. By analyzing the correlation of the airborne radon activity and the measured rate of events in NEXT-100, it is concluded that the detector operates in a virtually radon-free environment thanks to the radon abatement system of the LSC.
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Authors: C. Cortes-Parra, P. Novella, G. Martínez-Lema, H. Almazán, V. Álvarez, L. Arazi, I. J. Arnquist, F. Auria-Luna, S. Ayet, Y. Ayyad, C.D.R. Azevedo, F. Ballester, J. E. Barcelon, M. del Barrio-Torregrosa, J. M. Benlloch-Rodríguez, F. I. G. M. Borges, A. Brodoline, N. Byrnes, A. Castillo, E. Church, M. Cid, X. Cid Vidal, C.A.N. Conde, F. Cossio, R. Coupe, E. Dey, P. Dietz, C. Echeverria, M. Elorza, R. Esteve, R. Felkai, L. M. P. Fernandes, P. Ferrario, P. Ferrero Mancheño, F. W. Foss, Z. Freixa, J. García-Barrena, J.J. Gómez-Cadenas, J. W. R. Grocott, R. Guénette, J. M. Hauptman, C. A. O. Henriques, J. A. Hernando Morata, P. Herrero-Gómez, V. Herrero, C. Hervés Carrete, Y. Ifergan, A. F. B. Isabel, B. J. P. Jones, F. Kellerer, L. Larizgoitia, A. Larumbe, P. Lebrun, F. Lopez, N. López-March, R. Madigan, R. D. P. Mano, A. Marauri, A. P. Marques, J. Martín-Albo, A. Martínez, M. Martínez-Vara, R. L. Miller, K. Mistry, J. Molina-Canteras, F. Monrabal, C. M. B. Monteiro, F. J. Mora, K. E. Navarro, D. R. Nygren, E. Oblak, I. Osborne, J. Palacio, B. Palmeiro, A. Para, I. Parmaksiz, A. Pazos Álvarez, J. Pelegrin, M. Pérez Maneiro, M. Querol, J. Renner, I. Rivilla, C. Rogero, L. Rogers, B. Romeo, C. Romo-Luque, Elisa Ruiz-Chóliz, P. Saharia, F. P. Santos, J.M.F. dos Santos, M. Seemann, I. Shomroni, A. L. M. Silva, C. L. Da Silva, A. Simón, S. R. Soleti, M. Sorel, J. Soto-Otón, J. M. R. Teixeira, S. Teruel-Pardo
Institutions: University of the Basque Country, Iowa State University, University of Aveiro, University of Coimbra, The University of Texas at Arlington, Hebrew University of Jerusalem, Ben-Gurion University of the Negev, FZU ‒ Institute of Physics of the Academy of Sciences of the Czech Republic, Weizmann Institute of Science, Los Alamos National Laboratory, Manchester University, Argonne National Laboratory, Ikerbasque, Donostia International Physics Center, Universidade de Santiago de Compostela, Fermi National Accelerator Laboratory, Instituto de Física Corpuscular, Pacific Northwest National Laboratory, Instituto de Instrumentación para Imagen Molecular, Canfranc Underground Laboratory