Development of new materials for next-generation astroparticle physics experiments

Materials science is a multidisciplinary approach to various fields of physics and chemistry. The choice of the proper materials is crucial during design, R&D, and construction of an experiment where construction materials are the main source of background during data taking. Keeping materials-induced background under control is a key point for rare events physics searches. In this field, the background is due to particles whose interactions with the materials of the experimental apparatus can mimic a signal similar to the events that the experiment is looking for. Other unwanted particles can be detected and distinguished from the desired signal, but their detection affects the so-called dead time, in which the detector is blind for the tracing of the desired events. To avoid these drawbacks, detection strategies of unwanted particles are adopted through the construction of specific detectors, or vetoes, which have the objective of shielding the active volume of the experiment (i.e. the part used for the detection of the rare event). This thesis work is focused on these devices: on one hand, I worked on the construction of a neutron veto for the DarkSide- 20k experiment, on the other I tested some commercial organic scintillators in cryogenic environments. The latter project may pave the way for the integration of the aforementioned devices into rare-event physics experiments. Firstly I introduce the DarkSide-20k experiment, whose aim is the direct search for dark matter, based on the Weakly Interacting Massive Particle (WIMP) model. In this context, one of the main sources of background is represented by neutrons, whose interaction with the liquid argon, which is the active target material, could simulate a signal due to a WIMP. In order to overcome this issue, a neutron detector used as veto apparatus was designed, consisting of a 15 cm thick wall of polymethyl methacrylate (PMMA) loaded with gadolinium. The use of gadolinium is due to its high cross-section (which is a physical parameter that expresses the probability of a process) for neutron capture. All the materials involved in the veto construction must meet severe radiopurity criteria: all the compounds are subjected to screening, in order to measure the presence of isotopes such as 40K, 238U, and 232Th. Therefore, an R&D project was conducted for the development of an innovative and radiopure hybrid material consisting of PMMA containing a gadolinium-based compound. For our purposes, it was chosen gadolinium oxide (Gd2O3) in the form of nanoparticles (indicated as NPs in this work). Since this compound is not miscible in methyl methacrylate (MMA, the starting monomer), it is necessary to functionalize the NPs in order to overcome the sedimentation and to obtain a quite homogeneous sample, still maintaining all the additives in a small concentration in order to avoid possible background sources. During the research activity, I worked on the gadolinium oxide R&D, which proposes a possible strategy to produce radiopure and homogeneous samples that meet the experiment requirements. This process is also scalable to industrial productions. Also, several characterizations were performed in order to test the thermomechanical properties of the composite material. In chapter 1, I will introduce the state of the art in the dark matter (referred to in this work as DM) research field, where the DarkSide-20k experiment is inserted. In chapter 2, I will illustrate the DarkSide purpose and the detector (whose construction started in 2022). Mainly, I will focus on the veto apparatus and I will briefly discuss the background control requirements. In chapter 3 I will focus on the R&D project on the gadolinium-loaded PMMA, so the mixing and the polymerization procedures that have been developed. Also, I will show some results of the analyses conducted on the treated NPs, in order to evaluate the effectiveness of the functionalization and the stability of these grains in a colloidal solution. Chapter 4 is fully devoted to the characterizations of the polymeric samples, investigating the effect of the NPs doping on the thermomechanical properties of the polymeric matrix and testing the prototypes in a cryogenic environment (reproducing the conditions that will be encountered in the experiment). Chapter 5 is devoted to the description of the purification strategy which was adopted for a commercial surfactant involved in the synthesis process. In chapter 6, I will illustrate the work that has been done for the scaling of our production procedure to a partner industry. Also, in this chapter are reported some tests that have been done on the industrial samples. In chapter 7, finally, I will illustrate what has been done for the PESCE project, which is a grant funded by INFN for the past 3 years, whose purpose was the characterization of some organic scintillators in cryogenic environments. In the appendix, I briefly report additional projects that I followed during my Ph.D. years, related to astrophysics and space science, to which I contributed with my knowledge of materials science for the choice and characterization of the experimental apparata

The fantasmical gothic heterotopia in Rhode Montijo’s "Pablo’s Inferno"

Rhode Montijo’s work is characterized by a distinctive blend of diverse elements converging in his “fantasmical world”. As comic book artist, he is the author of the limited series "Pablo’s Inferno" (1999-2000), narrating a little Mexican American boy’s travel through the underworld. Accompanied by fallen demi-god Quetzal, Pablo embarks in a quest to (re)discover his cultural roots and commit to them. Like most of Montijo’s work, the comic book series holds an intrinsic gothic mode exploiting the playful nature of the comic medium and interrogating Mexican American heritage, by means of absorption of different genres, tropes, and diegetic elements. By examining the use of the Gothic distinctive of his work, the analysis will highlight the representation of the elements the author retrieved from his strong connection with Mexican heritage and the modes of children’s gothic fiction, revealing the unique cross-genre Montijo created to convey the identity related issues peculiar to the Mexican American experience.La obra de Rhode Montijo se caracteriza por ser una mezcla peculiar de distintos elementos que convergen en su propio “fantasmical world”. Como creador de cómics, es el autor de la miniserie "Pablo’s Inferno" (1999-2000), que recuenta el viaje de un niño mexicoamericano a través del inframundo. Acompañado por Quetzal, un semi-dios caído en desgracia, Pablos se embarca en una expedición en búsqueda de sus raíces culturales para comprometerse a ellas. Como acontece en la mayoría de los trabajos por Montijo, la miniserie presenta un modo gótico intrínseco que aprovecha la naturaleza lúdica del cómic y pone en tela de juicio el patrimonio cultural mexicoamericano, absorbiendo una variedad de géneros, tropos, y elementos diegéticos. Examinando el empleo del Gótico que caracteriza su trabajo, este análisis enfoca tanto la representación de los componentes que derivan de su conexión con el patrimonio cultural mexicano como los modos típicos de la ficción gótica para niños, revelando el género narrativo único que Montijo ha creado para expresas los asuntos identitarios propios de la experiencia mexicoamericana

The Hybridization of the Noir Genre as Expression of Ethnic Heritage: Rafael Navarro’s Sonambulo

In his ongoing comic book series Sonambulo, versatile artist Rafael Navarro has been able to channel his Mexican American cultural heritage by creating a unique blend of narrative genres. In his work, Navarro exploits classic American film noir as a fundamental reference and hybridizes it with elements distinctive to a shared Chicanx heritage, such as lucha libre cinema, horror folktales, and border-crossing metaphors; the construction of an oneiric dimension helps bring the narrative together, marking it with a peculiar ambiance. Drawingheavily on a diverse range of film genres, as well asethnocultural pivots, thiscomic book series carves outa definite spacein the panorama of the Mexican American production of popular culture, addinga powerful voice to the expression of US ethnic minorities.En su serie de cómic Sonambulo, el versátil artista Rafael Navarro ha conseguido canalizar su herencia cultural mexicoamericana, creando una mezcla única de distintos géneros narrativos. En su obra, Navarro toma el cine negro clásico estadounidense como referencia fundamental y la hibrida a través de elementos peculiares de una herencia chicana compartida, como por ejemplo el cine de luchadores, leyendas de terror, y metáforas del cruce fronterizo; la construcción de una dimensión onírica ayuda la armonización narrativa, creando una atmosfera distintiva. Inspirándose en una variedad de géneros cinematográficos, así como en pivotes etnoculturales, la serie forja un espacio definido en el panorama de la producción mexicoamericana de cultura popular, añadiendo una voz poderosa a la expresión de las minorías étnicas en los Estados Unidos

Rearticulating worlds through language: social justice and creative activism networks

For ethnolinguistic and sociocultural groups, language undeniably represents a fundamental mean of shared expression and construction of meaning. In the US, just language practices have been emerging as a form of resistance opposing the dominant monoglossic Anglo culture and its patterns of imposed assimilation of ethnolinguistic minorities. Connected to the Spanish-speaking communities, language justice activism promotes social equality, as well as the creation of translingual spaces and the thriving of an articulated network of social actors engaging local communities. The range of related activities results particularly adequate and fruitful in transnational, borderland contexts, fostered by binational collaborations and cooperation among art collectives. Raised at the beginning of the 21th century from Latin American experiences, the approach offered by "cartonera" workshops gives the border context a chance to raise language awareness and promote creative projects, precisely with a special attention to local multilingual communities. The production of handcrafted, independent publishing represents, in fact, a powerful mean of resistance against the dominant culture, giving the opportunity to narrate personal transnational stories in the language the bilingual speakers feel more comfortable to employ to express themselves and convey their message.En el caso de grupos etnolingüísticos y socioculturales, el lenguaje representa un medio fundamental al fin de compartir expresiones y construcciones de signifcado. En EE.UU., prácticas lingüísticas equitativas han ido apareciendo como formas de resistencia en contra de la cultura anglo –dominante y monoglósica– y sus mecanismos de asimilación impuesta a minorías etnolingüísticas. Radicado en las comunidades hispanohablantes, el activismo relacionado con la justicia lingüística promueve equidad social, así como la creación de espacios translingües y el desarrollo de una red de actores sociales que estimulen la participación de comunidades locales. La variedad de actividades promovidas resulta particularmente adecuada y fructífera en contextos transnacionales y fronterizos, impulsadas por colaboraciones binacionales y cooperaciones entre colectivos artísticos. Surgido al principio del siglo XXI de experiencias latinoamericanas, el enfoque ofrecido por los laboratorios cartoneros permite la concienciación acerca del multilingüismo y la promoción de proyectos creativos, precisamente con especial atención hacia las comunidades locales. La producción de libros artesanales como editoriales independientes representa un medio poderoso de resistencia en contra de la cultura dominante, proporcionando a los hablantes la oportunidad de narrar historias transnacionales personales en el idioma en que prefieran expresarse y comunicar su propio mensaje

Gentefied and the Representation of the Gentrification Related Latinx Conflicts

On February 21, 2020 Netflix launched Gentefied, a 10-episode long, fast-paced series revolving around a Mexican American family living in the LA neighborhood of Boyle Heights, showing their efforts to cope with daily needs, economic problems, and life dreams. Aside from its slice-of-life value, the series tackles a rather complex issue that has been raising a variety of conflicts among the inhabitants of areas historically populated by minorities: gentrification has been progressively changing the shape and quintessential nature of neighborhoods, increasing their economic value by renovating buildings and businesses in order to attract a more affluent population. “Pop” Casimiro (played by versatile Mexican actor Joaquín Cosío) and his three grandchildren Erik (J.J. Soria), Chris (Carlos Santos), and Ana (Karrie Martin) orbit around their beloved family-run taco shop. Through the articulation of the cousins’ relationships and networks, the series reconstructs the fundamental issues related with the neighborhood community internal conflicts generated by gentrification processes and, more in general, the assimilation processes imposed within a monoglossic national state. Erik is presented as a loyal, little educated yet book-loving, heavily tattooed, machista young man with an estranged pregnant girlfriend, ticking—and at the same time, challenging—most of the stereotyped features of a cholo. His conflict with Chris—who wishes to become a chef in fine dining restaurants—is pervasive and juxtaposes the clashing realities of a small family-run business and the luxury industry. Both within the family and the workplace, Chris is mocked and discriminated for his lighter skin tone and alleged guilt of betraying his own roots; nonetheless, he gets fired—and consequently ostracized by the industry—for directly confronting his employer about his racist attitudes. Ana embraces her ethnicity and sexuality, but as a struggling artist she ends up “selling out” too; her conflicts with Afro-Latina activist girlfriend Yessika (Julissa Calderon) embody the dilemmas faced by many Latinx to achieve career goals without being exploited by affluent, overbearing White agents. As their grandfather struggles to maintain the shop afloat, the family tries to unite efforts to avoid its closure while pursuing their dreams; yet, both their dreams and intents of transforming the shop to attract new clients will clash with the struggle to preserve the neighborhood from gentrification. Caught between her own affections and the principles she stands for, a distraught Yessika will lead a protest against the shop’s new activities. Without taking a defined position on the conflicts, the series succeeds in conveying the complexity of the internal, intersectional conflicts and—in fact—the impossibility of leaning starkly on one side or the other. It also effectively stages the underlying sociocultural and economic contexts in which—even without the intervention of gentrifying agency—a reconfiguration would have been inevitable for the neighborhood to adapt to current times and thrive, overcoming marginalization. Supported by a study of the mechanisms intrinsic to gentrification processes in the Latinx neighborhood, this paper will analyze them through their representation offered by Gentefied, pointing out its intrinsic values as well as fiction-related simplifications

Acercamientos a una expansión de la enseñanza en Estudios Norteamericanos a través de la cultura popular

The present study aims to consider an expanded approach to teaching American Studies at the Universidad de Alcalá, achieved by using popular culture texts to assist the comprehension and analysis of foreign sociocultural contexts. Given the pervasiveness of American products framed by an increased access provided by digital globalization, it would seem particularly useful to approach such texts from a critical academic perspective. Stemming from the answers a diverse range of students gave—and considering their limitations—the study delves into how popular culture informs and shapes the students’ disposition toward learning, consequently outlining how a course in American Studies could be developed in order to exploit such texts and effectively stimulate a more diverse understanding of the American context(s).El presente estudio tiene por objeto la expansión de la enseñanza de Estudios Norteamericanos en la Universidad de Alcalá a través de la implementación de textos de cultura popular para apoyar el proceso de comprensión y análisis de contextos socioculturales extranjeros. Considerando la penetración de productos estadounidenses en el marco de una mayor accesibilidad dada por la globalización digital, resulta particularmente útil el acercamiento a tales textos desde una perspectiva académica y crítica. Derivado de las respuestas proporcionadas por un grupo diverso de estudiantes, y teniendo en cuenta sus limitaciones, el estudio enfoca cómo la cultura popular informa y configura la disposición de los estudiantes hacia el aprendizaje, permitiendo plantear cómo se podría desarrollar una asignatura en Estudios Norteamericanos con el fin de explotar tales textos y estimular eficazmente un conocimiento más diverso de los contextos estadounidenses

Alien/alienígena : Barrier y la representación de la otredad fronteriza

La representación de la frontera México-EE.UU. se relaciona inevitablemente con la percepción mutua del otro lado, entrelazándose con la confrontación existente entre la sociedad estadounidense y la presencia -interna y externa- de lo latino, a menudo expresada a través de impactantes metáforas visuales. Publicado en 2015, la serie cómic Barrier -por Brian K. Vaughan, Marcos Martín y Muntse Vicente- desafía el discurso institucional y mediático sobre la frontera e inmigración; pese a su giro sci-fi, su cuento refleja choques reales existentes sobre el asunto fronterizo y el conflicto entre la cultura dominante Anglo y la latina.The representation of the US-Mexico border is strictly related to the perception of the mutual other side, which is bound to the confrontation between the US society and the Latino presence, often conveyed through visually compelling metaphors. Published in 2015, the comic series Barrier-by Brian K. Vaughan, Marcos Martín and Muntse Vicente-challenges the institutional and media discourse on the border and immigration; in spite of its sci-fi turn, the story reflects the existing clashes related to the border matter, as well as to the unresolved conflict between the US dominant Anglo culture and the Latino one.La representació de la frontera Mèxic-EUA es relaciona inevitablement amb la percepció mútua de l'altre costat, entrellaçant-se amb la confrontació existent entre la societat dels Estats Units i la presència -interna i externa- d'allò llatí, sovint expressada a través d'impactants metàfores visuals. Publicat en 2015, la sèrie còmic Barrier -per Brian K. Vaughan, Marcos Martín i Muntse Vicente- desafia el discurs institucional i mediàtic sobre la frontera i immigració; malgrat el seu gir sci-fi, el seu conte reflexa xocs reals existents sobre la qüestió fronterera i el conflicte entre la cultura dominant anglosaxona i la llatina