Search

New silicon 3-D-microdetectors have been developed to perform microdosimetry measurements for applications in hadron therapy. In this work, the charge collection efficiency (CCE) of an improved second generation of microdetectors having two different thicknesses (10 and 20 $\mu \text{m}$) and a diameter of 25 $\mu \text{m}$ has been studied by means of the ion beam induced charge (IBIC) technique. New methods to study the active volume and the CCE of microdosimeters are proposed and verified here. The results show that, for this new generation of microdetectors, the CCE is 100% for radial distances up to 10.2 $\mu \text{m}$ from the center of the device, and it rapidly decays between 10.2 $\mu \text{m}$ and the detector edge. The characterization of the CCE conducted here will allow us to completely explain the energy spectra obtained during the microdosimetry studies performed in clinical centers. [ABSTRACT FROM AUTHOR]

The use of protons and heavy ions for the treatment of tumors is increasing since it provides a better relative biological effectiveness (RBE) than traditional radiotherapy. Accurate knowledge of the energy deposition at submicrometric scales is paramount for RBE characterization. This paper shows the latest version of the silicon cylindrical microdosimeter array developed by the Instituto de Microelectrónica de Barcelona, Centro Nacional de Microelectrónica (IMB-CNM, Spain). The detector consists of a matrix of $11 \times 11$ cylindrical sensitive unit cells with individual readout etched within the silicon substrate available in different diameters and pitches between detectors. The detector employed in this paper had a diameter of $15~\mu \text{m}$ , a pitch of $200~\mu \text{m}$ , and a thickness of $5.5~\mu \text{m}$. The detectors were tested in the clinical facilities of Fondazione Centro Nazionale di Adronterapia Oncologica (CNAO) (Pavia, Italy) employing a 12C pencil beam at a therapeutic beam fluence rate. Microdosimetric spectra of lineal energy were measured in different depths of polymethyl methacrylate (PMMA) up to the Bragg peak. Results were then compared with Monte Carlo simulations using the FLUKA particle transport code, showing an excellent agreement between experimental and simulated microdosimetric distributions even at the high fluence rates associated with clinical beams. [ABSTRACT FROM AUTHOR]

An ultra-thin 3-D detector (U3DTHIN) with a 10-\mum-thick active region has been proposed to apply for microdosimetry in heavy ion therapy where the ion beam incidence is normal to the detector. The advantage of the detector is that the detector substrate below the silicon-on-insulator layer has been etched away. Extremely small columnar 3-D electrodes allow the detector to be fully depleted at very low biases with a minimum dead region due to their size. In this paper, a charge collection study of the U3DTHIN detector carried out using an ion beam-induced charge collection (IBICC) technique is presented. The IBICC study utilized a microbeam of 5.5 MeV He^2 + and 20 MeV^12C ions focused to approximately 1-\mum diameter. Full charge collection was observed from a bias as low as -10 V. A comparison of the detector response when irradiated from the front and rear side is also presented. [ABSTRACT FROM PUBLISHER]

The planned luminosity upgrade of the CERN LHC to the super LHC (sLHC) requires investigation of new radiation hard tracking detectors. Compared to the LHC, tracking detectors must withstand a 5–10 times higher radiation fluence. Promising radiation hard options are planar silicon detectors with n-side readout and silicon detectors in 3D technology, where columnar electrodes are etched into the silicon substrate. This article presents beam test measurements performed with planar and 3D n-in-p silicon strip detectors. The detectors were irradiated to different fluences, where the maximum fluence was 3\times 10^15 1 MeV neutron equivalent particles per square centimeter (neq/\rm cm^2) for the planar detectors and 2\times 10^15~neq/\rm cm^2 for the 3D detectors. In addition to signal measurements, charge sharing and resolution of both detector technologies are compared. An increased signal from the irradiated 3D detectors at high bias voltages compared to the signal from the unirradiated detector indicates that charge multiplication effects occur in the 3D detectors. At a bias voltage of 260 V, the 3D detector irradiated to 2\times 10^15~neq/\rm cm^2 yields a signal almost twice as high as the signal of the unirradiated detector. Only 30% of the signal of an unirradiated detector could be measured with the planar detector irradiated to 3\times 10^15~neq/\rm cm^2 at a bias voltage of 600 V, which was the highest bias voltage applied to this sensor. [ABSTRACT FROM AUTHOR]

For the planned luminosity upgrade of the CERN LHC to the sLHC new radiation hard technologies for the tracking detectors are investigated. Corresponding to the luminosity increase, the radiation dose will be approximately a factor of ten higher than for the detectors currently installed in the LHC experiments. One option for radiation tolerant detectors are 3D silicon detectors with columnar electrodes penetrating into the silicon bulk. This article reports results of beam test measurements performed with 3D-DDTC (Double-Sided, Double Type Column) silicon strip detectors, where the columns do not pass through the detector completely. The devices were produced by IMB-CNM (Barcelona, Spain) and by FBK-irst (Trento, Italy). Important properties like space-resolved charge collection and efficiency are investigated. [ABSTRACT FROM PUBLISHER]

Three-dimensional (3D) photodiode detectors offer advantages over standard planar photodiodes in a range of applications, including X-ray detection for synchrotrons and medical imaging. The principal advantage of these sensors for X-ray imaging is their low charge sharing between adjacent pixels, which could improve spatial and spectral resolution. A 'double-sided' 3D detector has been bonded to a Medipix2 single-photon-counting readout chip, and tested in a monochromatic X-ray beam at the Diamond synchrotron. Tests of the 3D detector's response spectrum and its Line Spread Function have shown that it has substantially lower charge sharing than a standard planar Medipix2 sensor. Additionally, the 3D detector was used to image diffraction rings produced by a powdered silicon sample, demonstrating the detector's use in a standard synchrotron experiment. [ABSTRACT FROM AUTHOR]

The planned upgrade to the CERN Large Hadron Collider (LHC), the Super-LHC (sLHC) will increase its luminosity by a factor of ten. This necessitates the development of silicon tracking detectors that are significantly more radiation resistant than the ones employed at the LHC. Currently, new detector technologies are being developed to cope with the increased levels of radiation damage at the sLHC. A possible radiation hard option for silicon short strip devices (SSD) in the inner layers of sLHC trackers are 3-D detectors with rows of columnar electrodes processed into the bulk material. These are joined together to form strips. While the excellent radiation hardness of this design has been proven before in lab experiments, a 3-D SSD prototype has now been investigated for the first time in a beam test with pions of a nominal energy of 180 GeV. The use of analog LHC-speed electronics, a beam telescope and time-resolved measurements allowed for detailed studies of the signal behavior on the hit strip and its neighboring strips. Charge collection and efficiency were as well measured with respect to time and point of incidence of the beam particles on the detector. The results of these measurements are presented in this paper. [ABSTRACT FROM AUTHOR]

Modern high-energy physics and astrophysics strip detectors have increased channel density to levels at which their connection with readout electronics has become very complex due to high pad pitch. Also, direct wire bonding is prevented by the fact that typically detector's pad pitch and electronics' pad pitch do not match. A high-pitch metal-on-glass technology is presented, that allows pad pitch adaptation between detectors and readout electronics. It consists of high-density metal lines on top of an insulating glass substrate. A photoresist layer is deposited covering the metal tracks for passivation and protection The technology is tested for conductivity, bondability, bonding pull force, peel off, and radiation hardness, and it is an established technology in the clean room of the CNM Institute in Barcelona. This technology has been chosen by the ATLAS Collaboration for the pad pitch adapters (PPA) of the SCT Endcap Modules, by a Compton camera project, and by other HEP groups for interconnection between detectors and readout electronics. [ABSTRACT FROM AUTHOR]