February 27, 2023 Technical note Open Access

Technical Design Report - TDR CYGNO-04/INITIUM

Giovanni Mazzitelli; Elisabetta Baracchini; Cesidio Capoccia; Laura Leonzi; Davide Pinci; Filippo Rosatelli; Sandro Tomassini; Fernando Domingues Amaro; Rita Antonietti; Luigi Benussi; Stefano Bianco; Michele Caponero; Danilo Santos Cardoso; Gianluca Cavoto; André Cortez; Igor Abritta Costa; Rita Joanna da Cruz Roque; Emiliano Dane; Giorgio Dho; Flaminia Di Giambattista; Emanuele Di Marco; Giovanni Grilli di Cortona; Giulia D'Imperio; Francesco Iacoangeli; Herman Pessoa Lima Júnior; Ernesto Kemp; Guilherme Sebastiao Pinheiro Lopes; Amaro da Silva Lopes Júnior; Giovanni Maccarrone; Rui Daniel Passos Mano; Robert Renz Marcelo Gregorio; David José Gaspar Marques; Alasdair Gregor McLean; Andrea Messina; Cristina Maria Bernardes Monteiro; Rafael Antunes Nobrega; Igor Fonseca Pains; Emiliano Paoletti; Luciano Passamonti; Fabrizio Petrucci; Stefano Piacentini; Davide Piccolo; Daniele Pierluigi; Atul Prajapati; Francesco Renga; Alessandro Russo; Joaquim Marques Ferreira dos Santos; Giovanna Saviano; Neil John Curwen Spooner; Roberto Tesauro; Samuele Torelli

The aim of this Technical Design Report is to illustrate the technological choices foreseen to be implemented in the construction of the CYGNO-04 demonstrator, motivate them against the experiment physics goals of CYGNO-30 and demonstrate the financial sustainability of the project. CYGNO-04 represents PHASE 1 of the long term CYGNO roadmap, towards the development of large high precision tracking gaseous Time Projection Chamber (TPC) for directional Dark Matter searches and solar neutrino spectroscopy.

The CYGNO project1 peculiarities reside in the optical readout of the light produced during the amplification of the primary ionization electrons in a stack of triple Gas Electron Multipliers (GEMs), thanks to the nice scintillation properties of the chosen He:CF4 gas mixture. To this aim, CYGNO is exploiting the fast progress in commercial scientific Active Pixel Sensors (APS) development for highly performing sCMOS cameras, whose high granularity and sensitivity allow to significantly boost tracking, improve particle identification and lower the energy threshold. The X-Y track project obtained from the reconstruction of the sCMOS images is combined with a PMT measurement to obtain a full 3D track reconstruction.

In addition, several synergic R&Ds based on the CYGNO experimental approach are under development in the CYGNO collaboration (see Sec 2) to further enhance the light yield by means of electro luminescence after the amplification stage, to improve the tracking performances by exploiting negative ion drift operation within the INITIUM ERC Consolidator Grant, and to boost the sensitivity to O(GeV) Dark Matter masses by employing hydrogen rich target towards the development of PHASE 2 (see Sec. 1.2).

While still under optimization and subject to possible significant improvements, the CYGNO experimental approach performances and capabilities demonstrated so far with prototypes allow to foresee the development of an O(30) m3 experiment by 2026 for a cost of O(10) MEUROs. A CYGNO-30 experiment would be able to give a significant contribution to the search and study of Dark Matter with masses below 10 GeV/c2 for both SI and SD coupling. In case of a Dark Matter observation claim by other experiments, the information provided by a directional detector such as CYGNO would be fundamental to positively confirm the galactic origin of the allegedly detected Dark Matter signal. CYGNO-30 could furthermore provide the first directional measurement of solar neutrinos from the pp chain, possibly extending to lower energies the Borexino measurement2.

In order to reach this goal, the CYGNO project is proceeding through a staged approach. The PHASE 0 50 L detector (LIME, recently installed underground LNGS) will validate the full performances of the optical readout via APS commercial cameras and PMTs and the Montecarlo simulation of the expected backgrounds.

The full CYGNO-04 demonstrator will be realized with all the technological and material choices foreseen for CYGNO-30, to demonstrate the scalability of the experimental approach and the potentialities of the large PHASE 2 detector to reach the expected physics goals.

The first PHASE 1 design anticipated a 1 m3 active volume detector with two back-to-back TPCs with a central cathode and 500 mm drift length. Each 1 m2 readout area would have been composed by 9 + 9 readout modules having the LIME PHASE 0 dimensions and layout. Time (end of INITIUM project by March 2025) and current space availability at underground LNGS (only Hall F) forced the rescaling of the PHASE 1 active volume and design to a 0.4 m3, hence CYGNO-04. CYGNO-04 will keep the back-to-back double TPC layout with 500 mm drift length each, but with an 800 x 500 mm2 readout area covered by a 2 + 2 modules based on LIME design. The reduction of the detector volume has no impact on the technological objectives of PHASE 1, since the modular design with central cathode, detector materials and shieldings and auxiliary systems are independent of the total volume. The physics reach (which is a byproduct of PHASE 1 and NOT an explicit goal) will be only very partially reduced (less than a factor 2 overall) since a smaller detector volume implies also a reduced background from internal materials radioactivity. In addition, the cost reduction of CYGNO-04 of about 1⁄3 with respect to CYGNO-1 illustrated in the CDR effectively makes the overall project more financially sustainable (see CBS in the last section).

In summary this document will explain:

•   the physical motivation of the CYGNO project and the technical motivations of the downscale of the PHASE 1 to CYGNO-04, 400 liters of active volume, with respect to the demonstrator presented in the CDR;

•   the results of R&D and the Montecarlo expectations for PHASE 0;

•   the technical choices, procedures and the executive drawings of CYGNO-04 in the Hall F of the LNGS;

•   safety evaluations and the interference/request to the LNGS services;

•   Project management, WBS/WBC, WP, GANTT, ecc