Hadron production in semi-inclusive measurements of deep-inelastic lepton nucleon scattering (SIDIS) is one of the most powerful tools to investigate the hadron structure. Despite the brilliant results that it has given in the past decades, some fundamental questions, like the emergence of hadron mass and spin from the hadron constituents remain unanswered. A new generation of experiments, like ePIC at the EIC and AMBER at CERN, is being planned to shed light on the phenomena that are still unknown. The core of SIDIS experiments is the measurement of the hadrons in the final state and their identification at high momenta (p ≳ 20 GeV/c) is crucial; in this momentum range, Ring Imaging Cherenkov Detectors (RICH) are the most effective way to address particle identification. RICH technology, based on the Cherenkov light emission of particles faster than light in a suitable medium, generally requires the detection of photons on a wide detection area. Gaseous Photon detectors represent a well established, cost-effective way to cover large areas; moreover they can be operated in the presence of a magnetic field. Recently, the development of the MPGD technology has improved the performance of gaseous photon detectors in terms of speed and reduction of the ion backflow at the photocathode. The R&D project presented in this thesis has the goal to export the MPGD-based photon detection technology developed for COMPASS RICH-1 to a future generation of experiments. The large amount of data and the high data rate foreseen at the future experiments suggest the use of a triggerless Data Acquisition (DAQ) system, however the front-end electronics used in COMPASS MPGD-based photon detector (APV25) can operate only in trigger mode. A candidate to substitute the APV25 is the VMM, a 64 channels, digital ASIC developed for MPGDs. A prototype chamber, with the same characteristics as COMPASS MPGD-based photon detectors has been built and tested both with a known front-end electronics and with the VMM to confirm the reliability of the latter. Tests were performed using an X-rays and a UV light source to mock Cherenkov photons. The two electronics gave comparable results with both photon sources, finding no obstacles to the use of VMM for the readout of MPGD-based Photon Detectors. Another limitation of the MPGD-based Photon Detectors is the fragility of the photocathodes, coated with (CsI): a severe decrease in quantum efficiency is observed following ion bombardment. In a gaseous detector the main source of ions is the avalanche process, so high radiation environments pose a limitation to the use of CsI based photocathodes. The thesis presents the study of a novel photoconverting material, hydrogenated nanodiamond (H-ND): its quantum efficiency is comparable with the one of CsI but it is more robust against radiation damage. In the thesis the production of the material is presented, as well as the spraying technique used to coat substrates. Presented results include studies of quantum efficiency, both in vacuum and in gas mixtures, and a study of radiation damage. The thesis is concluded by the study of the coupling of H-ND with COMPASS type Photon Detectors; results indicate that the two technologies can be combined for a more robust MPGD-based Photon Detetctor.
Un importante strumento per lo studio della struttura adronica sono le misure di produzione di adroni in processi di Deep Inelastic Scattering Semi – Inclusivo (SIDIS). Nei decenni passati queste misure hanno fornito preziose informazioni sulla struttura adronica, tuttavia alcune domande fondamentali, tra cui l’emergere della massa e dello spin adronici dai costituenti elementari, sono ancora senza risposta. Una nuova generazione di esperimenti, come ePIC a EIC e AMBER al CERN, e stata proposta per fare luce sui fenomeni ancora sconosciuti. Il fondamento dei processi SIDIS e la rivelazione degli adroni nello stato finale e la loro identificazione ad alto momento (p ≳ 20 GeV/c) e cruciale; in questo range di momenti, la tecnica piu efficace per identificare gli adroni e rappresentata dai rivelatori Ring Imaging Cherenkov, detti RICH. La tecnologia RICH, basata sull’emissione di luce Cherenkov da parte di particelle che viaggiano a velocita superluminale in un mezzo adatto, normalmente richiede la rivelazione di fotoni su una grande area sensibile. I rivelatori di fotoni a gas rappresentano una soluzione ben consolidata e relativamente economica per coprire grandi superfici; inoltre possono essere utilizzati in presenza di campi magnetici. Recentemente, lo sviluppo della tecnologia Micro-Pattern Gaseous Detectors (MPGD) ha migliorato le performance dei rivelatori a gas per quanto riguarda la velocita e la riduzione del flusso di ioni sul fotocatodo. Il progetto presentato in questa tesi ha lo scopo di esportare la tecnologia di rivelazione di fotoni, basata su MPGD, sviluppata per il RICH-1 di COMPASS a una nuova generazione di esperimenti. Il grande numero e l’alto rate di dati previsto agli esperimenti futuri suggeriscono l’uso di un sistema di acquisizione non triggerato; tuttavia l’ettronica di front-end attualmente in uso nei rivelatori di fotoni a MPGD di COMPASS (APV25) puo essere utilizzata solo in modalita triggerata. Un candidato per sostituire l’APV25 e il VMM, un ASIC digitale a 64 canali sviluppato come front-end per MPGD. Un prototipo di rivelatore, con le stesse caratteristiche dei rivelatori a MPGD di COMPASS e stato costruito e testato con un’elettronica dalla risposta nota e con il VMM, per confermare il funzionamento di quest’ultimo. I test sono stati fatti sia con una sorgente di raggi X che con una di fotoni UV, che imita i fotoni Cherenkov. Le due elettroniche hanno dato risposte compatibili con entrambe le sorgenti, eterminando l’assenza di ostacoli all’uso del VMM per il readout di rivelatori di fotoni con tecnologia MPGD. Un’ulteriore limitazione dei rivelatori di fotoni con tecnologia MPGD e la fragilita dei fotocatodi a ioduro di cesio (CsI): un’importante riduzione di efficienza quantica si osserva a causa del bombardamento di ioni. In un rivelatore a gas la principale sorgente di ioni e il fenomeno di moltiplica della carica, pertanto ambienti ad alta radiazione pongono un limite all’uso del CsI come fotocatodo. Questa tesi presenta lo studio di un nuovo materiale fotoconvertitore, la polvere di nanodiamante idrogenato (H-ND): la sua efficienza quantica e confrontabile con quella del CsI ma e piu robusto contro il danno da radiazione. Nella tesi sono presentati sia la produzione del materiale sia la tecnica con cui esso viene depositato su un substrato. I risultati includono studi di efficienza quantica sia in vuoto che in gas, e uno studio del danno da radiazione. La tesi e conclusa dallo studio dell’accoppiamento dei H-ND con i rivelatori di fotoni a MPGD; i risultati indicano che le due tecnologie possono essere combinate per costruire un rivelatore di fotoni robusto alla radiazione.
R&D for high-momentum hadron identification: from COMPASS RICH towards particle identification at the future Electron Ion Collider / D'Ago, Daniele. - (2023 May 05).
R&D for high-momentum hadron identification: from COMPASS RICH towards particle identification at the future Electron Ion Collider
D'AGO, DANIELE
2023-05-05
Abstract
Hadron production in semi-inclusive measurements of deep-inelastic lepton nucleon scattering (SIDIS) is one of the most powerful tools to investigate the hadron structure. Despite the brilliant results that it has given in the past decades, some fundamental questions, like the emergence of hadron mass and spin from the hadron constituents remain unanswered. A new generation of experiments, like ePIC at the EIC and AMBER at CERN, is being planned to shed light on the phenomena that are still unknown. The core of SIDIS experiments is the measurement of the hadrons in the final state and their identification at high momenta (p ≳ 20 GeV/c) is crucial; in this momentum range, Ring Imaging Cherenkov Detectors (RICH) are the most effective way to address particle identification. RICH technology, based on the Cherenkov light emission of particles faster than light in a suitable medium, generally requires the detection of photons on a wide detection area. Gaseous Photon detectors represent a well established, cost-effective way to cover large areas; moreover they can be operated in the presence of a magnetic field. Recently, the development of the MPGD technology has improved the performance of gaseous photon detectors in terms of speed and reduction of the ion backflow at the photocathode. The R&D project presented in this thesis has the goal to export the MPGD-based photon detection technology developed for COMPASS RICH-1 to a future generation of experiments. The large amount of data and the high data rate foreseen at the future experiments suggest the use of a triggerless Data Acquisition (DAQ) system, however the front-end electronics used in COMPASS MPGD-based photon detector (APV25) can operate only in trigger mode. A candidate to substitute the APV25 is the VMM, a 64 channels, digital ASIC developed for MPGDs. A prototype chamber, with the same characteristics as COMPASS MPGD-based photon detectors has been built and tested both with a known front-end electronics and with the VMM to confirm the reliability of the latter. Tests were performed using an X-rays and a UV light source to mock Cherenkov photons. The two electronics gave comparable results with both photon sources, finding no obstacles to the use of VMM for the readout of MPGD-based Photon Detectors. Another limitation of the MPGD-based Photon Detectors is the fragility of the photocathodes, coated with (CsI): a severe decrease in quantum efficiency is observed following ion bombardment. In a gaseous detector the main source of ions is the avalanche process, so high radiation environments pose a limitation to the use of CsI based photocathodes. The thesis presents the study of a novel photoconverting material, hydrogenated nanodiamond (H-ND): its quantum efficiency is comparable with the one of CsI but it is more robust against radiation damage. In the thesis the production of the material is presented, as well as the spraying technique used to coat substrates. Presented results include studies of quantum efficiency, both in vacuum and in gas mixtures, and a study of radiation damage. The thesis is concluded by the study of the coupling of H-ND with COMPASS type Photon Detectors; results indicate that the two technologies can be combined for a more robust MPGD-based Photon Detetctor.File | Dimensione | Formato | |
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Descrizione: R&D for high-momentum hadron identification: from COMPASS RICH towards particle identification at the future Electron Ion Collider
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