Basso, L., Belyaev, A., Chowdhury, D., Hirsch, M., Khalil, S., Moretti, S., et al. (2013). Proposal for generalised supersymmetry Les Houches Accord for see-saw models and PDG numbering scheme. Comput. Phys. Commun., 184(3), 698–719.
Abstract: The SUSY Les Houches Accord (SLHA) 2 extended the first SLHA to include various generalisations of the Minimal Supersymmetric Standard Model (MSSM) as well as its simplest next-to-minimal version. Here, we propose further extensions to it, to include the most general and well-established see-saw descriptions (types I/II/III, inverse, and linear) in both an effective and a simple gauged extension of the MSSM framework. In addition, we generalise the PDG numbering scheme to reflect the properties of the particles. (c) 2012 Elsevier B.V. All rights reserved.
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Park, B. Y., Paeng, W. G., & Vento, V. (2019). The inhomogeneous phase of dense skyrmion matter. Nucl. Phys. A, 989, 231–245.
Abstract: It was predicted qualitatively in ref. [I] that skyrmion matter at low density is stable in an inhomogeneous phase where skyrmions condensate into lumps while the remaining space is mostly empty. The aim of this paper is to proof quantitatively this prediction. In order to construct an inhomogeneous medium we distort the original FCC crystal to produce a phase of planar structures made of skyrmions. We implement mathematically these planar structures by means of the 't Hooft instanton solution using the Atiyah-Manton ansatz. The results of our calculation of the average density and energy confirm the prediction suggesting that the phase diagram of the dense skyrmion matter is a lot more complex than a simple phase transition from the skyrmion FCC crystal lattice to the half-skyrmion CC one. Our results show that skyrmion matter shares common properties with standard nuclear matter developing a skin and leading to a binding energy equation which resembles the Weiszacker mass formula.
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Pastore, A., Davesne, D., & Navarro, J. (2015). Linear response of homogeneous nuclear matter with energy density functionals. Phys. Rep., 563, 1–67.
Abstract: Response functions of infinite nuclear matter with arbitrary isospin asymmetry are studied in the framework of the random phase approximation. The residual interaction is derived from a general nuclear Skyrme energy density functional. Besides the usual central, spin-orbit and tensor terms it could also include other components as new density-dependent terms or three-body terms. Algebraic expressions for the response functions are obtained from the Bethe-Salpeter equation for the particle-hole propagator. Applications to symmetric nuclear matter, pure neutron matter and asymmetric nuclear matter are presented and discussed. Spin-isospin strength functions are analyzed for varying conditions of density, momentum transfer, isospin asymmetry, and temperature for some representative Skyrme functionals. Particular attention is paid to the discussion of instabilities, either real or unphysical, which could manifest in finite nuclei.
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Gimenez-Alventosa, V., Gimenez, V., Ballester, F., Vijande, J., & Andreo, P. (2018). Correction factors for ionization chamber measurements with the 'Valencia' and 'large field Valencia' brachytherapy applicators. Phys. Med. Biol., 63(12), 125004–10pp.
Abstract: Treatment of small skin lesions using HDR brachytherapy applicators is a widely used technique. The shielded applicators currently available in clinical practice are based on a tungsten-alloy cup that collimates the source-emitted radiation into a small region, hence protecting nearby tissues. The goal of this manuscript is to evaluate the correction factors required for dose measurements with a plane-parallel ionization chamber typically used in clinical brachytherapy for the 'Valencia' and 'large field Valencia' shielded applicators. Monte Carlo simulations have been performed using the PENELOPE-2014 system to determine the absorbed dose deposited in a water phantom and in the chamber active volume with a Type A uncertainty of the order of 0.1%. The average energies of the photon spectra arriving at the surface of the water phantom differ by approximately 10%, being 384 keV for the 'Valencia' and 343 keV for the 'large field Valencia'. The ionization chamber correction factors have been obtained for both applicators using three methods, their values depending on the applicator being considered. Using a depth-independent global chamber perturbation correction factor and no shift of the effective point of measurement yields depth-dose differences of up to 1% for the 'Valencia' applicator. Calculations using a depth-dependent global perturbation factor, or a shift of the effective point of measurement combined with a constant partial perturbation factor, result in differences of about 0.1% for both applicators. The results emphasize the relevance of carrying out detailed Monte Carlo studies for each shielded brachytherapy applicator and ionization chamber.
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Candela-Juan, C., Niatsetski, Y., van der Laarse, R., Granero, D., Ballester, F., Perez-Calatayud, J., et al. (2016). Design and characterization of a new high-dose-rate brachytherapy Valencia applicator for larger skin lesions. Med. Phys., 43(4), 1639–1648.
Abstract: Purpose: The aims of this study were (i) to design a new high-dose-rate (HDR) brachytherapy applicator for treating surface lesions with planning target volumes larger than 3 cm in diameter and up to 5 cm in size, using the microSelectron-HDR or Flexitron afterloader (Elekta Brachytherapy) with a Ir-192 source; (ii) to calculate by means of the Monte Carlo (MC) method the dose distribution for the new applicator when it is placed against a water phantom; and (iii) to validate experimentally the dose distributions in water. Methods: The PENELOPE2008 MC code was used to optimize dwell positions and dwell times. Next, the dose distribution in a water phantom and the leakage dose distribution around the applicator were calculated. Finally, MC data were validated experimentally for a 192Ir mHDR-v2 source by measuring (i) dose distributions with radiochromic EBT3 films (ISP); (ii) percentage depth-dose (PDD) curve with the parallel-plate ionization chamber Advanced Markus (PTW); and (iii) absolute dose rate with EBT3 films and the PinPoint T31016 (PTW) ionization chamber. Results: The new applicator is made of tungsten alloy (Densimet) and consists of a set of interchangeable collimators. Three catheters are used to allocate the source at prefixed dwell positions with preset weights to produce a homogenous dose distribution at the typical prescription depth of 3 mm in water. The same plan is used for all available collimators. PDD, absolute dose rate per unit of air kerma strength, and off-axis profiles in a cylindrical water phantom are reported. These data can be used for treatment planning. Leakage around the applicator was also scored. The dose distributions, PDD, and absolute dose rate calculated agree within experimental uncertainties with the doses measured: differences of MC data with chamber measurements are up to 0.8% and with radiochromic films are up to 3.5%. Conclusions: The new applicator and the dosimetric data provided here will be a valuable tool in clinical practice, making treatment of large skin lesions simpler, faster, and safer. Also the dose to surrounding healthy tissues is minimal.
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NOMAD Collaboration(Kullenberg, C. T. et al), Cervera-Villanueva, A., & Gomez-Cadenas, J. J. (2012). A search for single photon events in neutrino interactions. Phys. Lett. B, 706(4-5), 268–275.
Abstract: We present a search for neutrino induced events containing a single, exclusive photon using data from the NOMAD experiment at the CERN SPS where the average energy of the neutrino flux is similar or equal to 25 GeV. The search is motivated by an excess of electron-like events in the 200-475 MeV energy region as reported by the MiniBooNE experiment. In NOMAD, photons are identified via their conversion to e(+)e(-) in an active target embedded in a magnetic field. The background to the single photon signal is dominated by the asymmetric decay of neutral pions produced either in a coherent neutrino-nucleus interaction, or in a neutrino-nucleon neutral current deep inelastic scattering, or in an interaction occurring outside the fiducial volume. All three backgrounds are determined in situ using control data samples prior to opening the 'signal-box'. In the signal region, we observe 155 events with a predicted background of 129.2 +/- 8.5 +/- 3.3. We interpret this as null evidence for excess of single photon events, and set a limit. Assuming that the hypothetical single photon has a momentum distribution similar to that of a photon from the coherent pi(0) decay, the measurement yields an upper limit on single photon events, < 4.0 x 10(-4) per nu(mu) charged current event. Narrowing the search to events where the photon is approximately collinear with the incident neutrino, we observe 78 events with a predicted background of 76.6 +/- 4.9 +/- 1.9 yielding a more stringent upper limit, < 1.6 x 10(-4) per nu(mu) charged current event.
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Unno, Y. et al, Garcia, C., Jimenez, J., Lacasta, C., Marti-Garcia, S., & Soldevila, U. (2014). Development of n(+) -in-p large-area silicon microstrip sensors for very high radiation environments-ATLAS12 design and initial results. Nucl. Instrum. Methods Phys. Res. A, 765, 80–90.
Abstract: We have been developing a novel radiation tolerant n(+)-in-p silicon microstrip sensor for very high radiation environments, aiming for application in the high luminosity large hadron collider. The sensors are fabricated in 6 in., p-type, float zone wafers, where large area strip sensor designs are laid out together with a number of miniature sensors. Radiation tolerance has been studied with ATLAS07 sensors and with independent structures. The ATLAS07 design was developed into new ATLAS12 designs. The ATLAS12A large-area sensor is made towards an axial strip sensor and the ATLAS12M towards a stereo strip sensor. New features to the ATLAS12 sensors are two dicing lines: standard edge space of 910 pm and slim edge space of 450 pm, a gated punch-through protection structure, and connection of orphan strips in a triangular corner of stereo strips. We report the design of the ATLAS12 layouts and initial measurements of the leakage current after dicing and the resistivity of the wafers.
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Helling, C. et al, Bernabeu, J., Lacasta, C., & Solaz, C. (2020). Strip sensor performance in prototype modules built for ATLAS ITk. Nucl. Instrum. Methods Phys. Res. A, 978, 164402–6pp.
Abstract: ATLAS experiment is preparing an upgrade of its detector for High-Luminosity LHC (HL-LHC) operation. The upgrade involves installation of the new all-silicon Inner Tracker (ITk). In the context of the ITk preparations, more than 80 strip modules were built with prototype barrel sensors. They were tested with electrical readout on a per-channel basis. In general, an excellent performance was observed, consistent with previous ASIC-level and sensor-level tests. However, the lessons learned included two phenomena important for the future phases of the project. First was the need to store and test the modules in a dry environment due to humidity sensitivity of the sensors. The second was an observation of high noise regions for 2 modules. The high noise regions were tested further in several ways, including monitoring the performance as a function of time and bias voltage. Additionally, direct sensor-level tests were performed on the affected channels. The inter-strip resistance and bias resistance tests showed low values, indicating a temporary loss of the inter-strip isolation. A subsequent recovery of the noise performance was observed. We present the test details, an analysis of how the inter-strip isolation affects the module noise, and the relationship with sensor-level quality control tests.
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Bach, E. et al, Bernabeu, J., Lacasta, C., Solaz, C., & Soldevila, U. (2024). Analysis of the quality assurance results from the initial part of production of the ATLAS18 ITK strip sensors. Nucl. Instrum. Methods Phys. Res. A, 1064, 169435–8pp.
Abstract: The production of strip sensors for the ATLAS Inner Tracker (ITk) started in 2021. Since then, a Quality Assurance (QA) program has been carried out continuously, by using specific test structures, in parallel to the Quality Control (QC) inspection of the sensors. The QA program consists of monitoring sensor-specific characteristics and the technological process variability, before and after the irradiation with gammas, neutrons, and protons. After two years, half of the full production volume has been reached and we present an analysis of the parameters measured as part of the QA process. The main devices used for QA purposes are miniature strip sensors, monitor diodes, and the ATLAS test chip, which contains several test structures. Such devices are tested by several sites across the collaboration depending on the type of samples (non-irradiated components or irradiated with protons, neutrons, or gammas). The parameters extracted from the tests are then uploaded to a database and analyzed by Python scripts. These parameters are mainly examined through histograms and timeevolution plots to obtain parameter distributions, production trends, and meaningful parameter-to-parameter correlations. The purpose of this analysis is to identify possible deviations in the fabrication or the sensor quality, changes in the behavior of the test equipment at different test sites, or possible variability in the irradiation processes. The conclusions extracted from the QA program have allowed test optimization, establishment of control limits for the parameters, and a better understanding of device properties and fabrication trends. In addition, any abnormal results prompt immediate feedback to a vendor.
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Ullan, M., Benitez, V., Quirion, D., Zabala, M., Pellegrini, G., Lozano, M., et al. (2014). Low-resistance strip sensors for beam-loss event protection. Nucl. Instrum. Methods Phys. Res. A, 765, 252–257.
Abstract: AC coupled silicon strip sensors can be damaged in case of a beam loss due to the possibility of a large charge accumulation in the bulk, developing very high voltages across the coupling capacitors which can destroy them. Punch-through structures are currently used to avoid this problem helping to evacuate the accumulated charge as large voltages are developing. Nevertheless, previous experiments, performed with laser pulses, have shown that these structures can become ineffective in relatively long strips. The large value of the implant resistance can effectively isolate the “far” end of the strip from the punchthrough structure leading to large voltages. We present here our developments to fabricate lowresistance strip sensors to avoid this problem. The deposition of a conducting material in contact with the implants drastically reduces the strip resistance, assuring the effectiveness of the punch-through structures. First devices have been fabricated with this new technology. Initial results with laser tests show the expected reduction in peak voltages on the low resistivity implants. Other aspects of the sensor performance, including the signal formation, are not affected by the new technology.
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