Inverse Low Gain Avalanche Detectors (iLGADs) for precise tracking and timing applications

Low Gain Avalanche Detector (LGAD) is the baseline sensing technology of the recently proposed Minimum Ionizing Particle (MIP) end-cap timing detectors (MTD) at the Atlas and CMS experiments. The current MTD sensor is designed as a multi-pad matrix detector delivering a poor position resolution, due to the relatively large pad area, around 1 $mm^2$; and a good timing resolution, around 20-30 ps. Besides, in his current technological incarnation, the timing resolution of the MTD LGAD sensors is severely degraded once the MIP particle hits the inter-pad region since the signal amplification is missing for this region. This limitation is named as the LGAD fill-factor problem. To overcome the fill factor problem and the poor position resolution of the MTD LGAD sensors, a p-in-p LGAD (iLGAD) was introduced. Contrary to the conventional LGAD, the iLGAD has a non-segmented deep p-well (the multiplication layer). Therefore, iLGADs should ideally present a constant gain value over all the sensitive region of the device without gain drops between the signal collecting electrodes; in other words, iLGADs should have a 100${\%}$ fill-factor by design. In this paper, tracking and timing performance of the first iLGAD prototypes is presented.Comment: Conference Proceedings of VCI2019, 15th Vienna Conference of Instrumentation, February 18-22, 2019, Vienna, Austri

Recent Technological Developments on LGAD and iLGAD Detectors for Tracking and Timing Applications

This paper reports the last technological development on the Low Gain Avalanche Detector (LGAD) and introduces a new architecture of these detectors called inverse-LGAD (iLGAD). Both approaches are based on the standard Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray detection applications, including an internal multiplication of the charge generated by radiation. The multiplication is inherent to the basic n++-p+-p structure, where the doping profile of the p+ layer is optimized to achieve high field and high impact ionization at the junction. The LGAD structures are optimized for applications such as tracking or timing detectors for high energy physics experiments or medical applications where time resolution lower than 30 ps is required. Detailed TCAD device simulations together with the electrical and charge collection measurements are presented through this work.Comment: Keywords: silicon detectors, avalanche multiplication, timing detectors, tracking detectors. 8 pages. 8 Figure

Radiation Hardness of Thin Low Gain Avalanche Detectors

Low Gain Avalanche Detectors (LGAD) are based on a n++-p+-p-p++ structure where an appropriate doping of the multiplication layer (p+) leads to high enough electric fields for impact ionization. Gain factors of few tens in charge significantly improve the resolution of timing measurements, particularly for thin detectors, where the timing performance was shown to be limited by Landau fluctuations. The main obstacle for their operation is the decrease of gain with irradiation, attributed to effective acceptor removal in the gain layer. Sets of thin sensors were produced by two different producers on different substrates, with different gain layer doping profiles and thicknesses (45, 50 and 80 um). Their performance in terms of gain/collected charge and leakage current was compared before and after irradiation with neutrons and pions up to the equivalent fluences of 5e15 cm-2. Transient Current Technique and charge collection measurements with LHC speed electronics were employed to characterize the detectors. The thin LGAD sensors were shown to perform much better than sensors of standard thickness (~300 um) and offer larger charge collection with respect to detectors without gain layer for fluences <2e15 cm-2. Larger initial gain prolongs the beneficial performance of LGADs. Pions were found to be more damaging than neutrons at the same equivalent fluence, while no significant difference was found between different producers. At very high fluences and bias voltages the gain appears due to deep acceptors in the bulk, hence also in thin standard detectors

Gain and time resolution of 45 μ\mum thin Low Gain Avalanche Detectors before and after irradiation up to a fluence of 101510^{15} neq_{eq}/cm2^2

Low Gain Avalanche Detectors (LGADs) are silicon sensors with a built-in charge multiplication layer providing a gain of typically 10 to 50. Due to the combination of high signal-to-noise ratio and short rise time, thin LGADs provide good time resolutions. LGADs with an active thickness of about 45 $\mu$m were produced at CNM Barcelona. Their gains and time resolutions were studied in beam tests for two different multiplication layer implantation doses, as well as before and after irradiation with neutrons up to $10^{15}$ n$_{eq}$/cm$^2$. The gain showed the expected decrease at a fixed voltage for a lower initial implantation dose, as well as for a higher fluence due to effective acceptor removal in the multiplication layer. Time resolutions below 30 ps were obtained at the highest applied voltages for both implantation doses before irradiation. Also after an intermediate fluence of $3\times10^{14}$ n$_{eq}$/cm$^2$, similar values were measured since a higher applicable reverse bias voltage could recover most of the pre-irradiation gain. At $10^{15}$ n$_{eq}$/cm$^2$, the time resolution at the maximum applicable voltage of 620 V during the beam test was measured to be 57 ps since the voltage stability was not good enough to compensate for the gain layer loss. The time resolutions were found to follow approximately a universal function of gain for all implantation doses and fluences.Comment: 17 page

The Rhizophagus irregularis Genome Encodes Two CTR Copper Transporters That Mediate Cu Import Into the Cytosol and a CTR-Like Protein Likely Involved in Copper Tolerance

Arbuscular mycorrhizal fungi increase fitness of their host plants under Cu deficient and toxic conditions. In this study, we have characterized two Cu transporters of the CTR family (RiCTR1 and RiCTR2) and a CTR-like protein (RiCTR3A) of Rhizophagus irregularis. Functional analyses in yeast revealed that RiCTR1 encodes a plasma membrane Cu transporter, RiCTR2 a vacuolar Cu transporter and RiCTR3A a plasma membrane protein involved in Cu tolerance. RiCTR1 was more highly expressed in the extraradical mycelia (ERM) and RiCTR2 in the intraradical mycelia (IRM). In the ERM, RiCTR1 expression was up-regulated by Cu deficiency and down-regulated by Cu toxicity. RiCTR2 expression increased only in the ERM grown under severe Cu-deficient conditions. These data suggest that RiCTR1 is involved in Cu uptake by the ERM and RiCTR2 in mobilization of vacuolar Cu stores. Cu deficiency decreased mycorrhizal colonization and arbuscule frequency, but increased RiCTR1 and RiCTR2 expression in the IRM, which suggest that the IRM has a high Cu demand. The two alternatively spliced products of RiCTR3, RiCTR3A and RiCTR3B, were more highly expressed in the ERM. Up-regulation of RiCTR3A by Cu toxicity and the yeast complementation assays suggest that RiCTR3A might function as a Cu receptor involved in Cu tolerance

Beam test results of a 16 ps timing system based on ultra-fast silicon detectors

In this paper we report on the timing resolution of the first production of 50 micro-meter thick Ultra-Fast Silicon Detectors (UFSD) as obtained in a beam test with pions of 180 GeV/c momentum. UFSD are based on the Low-Gain Avalanche Detectors (LGAD) design, employing n-on-p silicon sensors with internal charge multiplication due to the presence of a thin, low-resistivity diffusion layer below the junction. The UFSD used in this test belongs to the first production of thin (50 {\mu}m) sensors, with an pad area of 1.4 mm2. The gain was measured to vary between 5 and 70 depending on the bias voltage. The experimental setup included three UFSD and a fast trigger consisting of a quartz bar readout by a SiPM. The timing resolution, determined comparing the time of arrival of the particle in one or more UFSD and the trigger counter, for single UFSD was measured to be 35 ps for a bias voltage of 200 V, and 26 ps for a bias voltage of 240 V, and for the combination of 3 UFSD to be 20 ps for a bias voltage of 200 V, and 15 ps for a bias voltage of 240 V.Comment: 7 pages, 8 figures, 1 table, Subm. to NIM

Home parenteral nutrition registry in Spain for the year 2010: NADYA-SENPE group

Objetivos: Comunicar los datos del Registro del Grupo NADYA SENPE de Nutrición Parenteral Domiciliaria NPD en España del año 2010. Material y métodos: Estudio descriptivo de la base de datos del Registro de ámbito nacional de NPD del grupo NADYA-SENPE (1 de enero de 2010 al 31 de diciembre de 2010). Para el cálculo de prevalencias se utilizó los últimos datos publicados por el Instituto Nacional de Estadística. Resultados: Se registraron 148 pacientes procedentes de 23 hospitales, 86 mujeres (58,11%) y 9 niños (6,08%). La edad media de los 139 pacientes adultos fue de 53,06 ± 15,41 años. La duración media de la NPD fue de 316,97 días/paciente. El diagnóstico más frecuente en los niños (menores de 14 años) fue intestino corto traumático con 5 casos (55,55%) y en los adultos la neoplasia en tratamiento paliativo 29 (19,59%). El motivo de la indicación de la NPD fue el síndrome de intestino corto en 74 ocasiones (47%). La vía de acceso más frecuentemente registrada fue el catéter tunelizado en 36 (22,78%) casos seguido del reservorio en 13 (8,23%) y otras vías en 3 ocasiones (1,90%). Se registraron 23 infecciones relacionadas con el catéter (82,14%), lo que representa 0,49/1000 días de NP y todas ellas ocurrieron en los adultos. A lo largo del año finalizaron 24 episodios de NPD, la causa más frecuente fue el paso a la vía oral en 12 episodios (50%). Se registró que los pacientes tenían una actividad normal en 70 episodios de NPD (44,30%) con una total autonomía en 88 de episodios (55,69%). Se identificaron 39 (24,68%) posibles candidatos para trasplante intestinal. Conclusiones: El número de pacientes registrados es discretamente inferior al del año anterior, aunque el número de hospitales participantes es el mismo. La complicación más frecuente sigue siendo la infección relacionada con el catéter aunque ha disminuido su incidencia respecto a años anteriores, presentándose la tasa más baja desde la creación del registro. Las diferencias en la participación en el registro observadas por Comunidades Autónomas lleva a plantear el desarrollo de estrategias de implementación del registro. Se observa un aumento progresivo de la duración de los días de NPD a lo largo de los años que hace pensar en la cronicidad de algunos pacientes, pero nos obliga a estudiar la existencia de un posible factor de confusión, en el caso de que existiera un olvido de cierre de algún episodio por lo que se hace necesario actualizar el registro con sistemas de alertas periódicas que faciliten la revisión de los pacientes incluidos y optimice la validez del registroObjectives: To report the Group Registry NADYASENPE data about home parenteral nutrition (HPN) in Spain in 2010. Material and methods: A descriptive study of the database of the national registry of HPN of NADYA-SENPE (December 10, 2009 to December 10, 2010). For the calculation of prevalence the latest data published by the Institute National Statistics Office (01/01/2009) was used. Results: There were registered 148 patients from 23 hospitals, 86 women (58.11%) and 9 children (6.08%). The average age of the 139 patients older than 14 years was 53.06 ± 15.41 years. The average duration of HPN was 316.97 days/patient. The most common diagnosis in those younger than 14 years was short bowel traumatic with 5 cases (55.55%) and in those older than 14 years, palliative care cancer with 29 cases (19.59%). The reason for the indication for HPN was short bowel syndrome in 74 cases (47%). The access via most frequently recorded was tunneled catheter in 36 cases (22.78%) followed by implanted port-catheters in 13 cases (8.23%) and other pathways in 3 cases (1.90%). There were 23 catheterrelated infections (82.14%) which represented 0.49 /1,000 days of PN, all of which occurred in cases older than 14 years. During the year 24 episodes of HPN ended, the most frequent cause was the transition to oral nutrition in 12 episodes (50%). It was reported that patients had a normal activity in 70 episodes of HPN (44.30%) with complete autonomy in 88 episodes (55.69%). Some patients 39 (24.68%) were potential candidates for intestinal transplantation. Conclusions: The number of registered patients is slightly lower than the previous year, although the number of participating hospitals is the same. The most frequent complication remains catheter-related infection but its incidence has decreased from previous years, presenting the lowest rate since the creation of the record. Differences in participation in the registry observed in the Autonomous Communities causes the development of implementation strategies. There is a gradual increase in day length of HPN over the years, which suggests the chronic treatments of some patients and obliges to study the existence of a possible confounding factor, in case there is an oversight of closing an episode. Therefore, it is necessary to update the registry with warning systems that facilitate periodic review of the patients and optimize the validity of registratio

Colon cancer subtypes: Concordance, effect on survival and selection of the most representative preclinical models

Multiple gene-expression-based subtypes have been proposed for the molecular subdivision of colon cancer in the last decade. We aimed to cross-validate these classifiers to explore their concordance and their power to predict survival. A gene-chip-based database comprising 2,166 samples from 12 independent datasets was set up. A total of 22 different molecular subtypes were re-trained including the CCHS, CIN25, CMS, ColoGuideEx, ColoGuidePro, CRCassigner, MDA114, Meta163, ODXcolon, Oncodefender, TCA19, and V7RHS classifiers as well as subtypes established by Budinska, Chang, DeSousa, Marisa, Merlos, Popovici, Schetter, Yuen, and Watanabe (first authors). Correlation with survival was assessed by Cox proportional hazards regression for each classifier using relapse-free survival data. The highest efficacy at predicting survival in stage 2-3 patients was achieved by Yuen (p = 3.9e-05, HR = 2.9), Marisa (p = 2.6e-05, HR = 2.6) and Chang (p = 9e-09, HR = 2.35). Finally, 61 colon cancer cell lines from four independent studies were assigned to the closest molecular subtype. © 2016 The Author(s)