-
[show abstract]
[hide abstract]
ABSTRACT: A system for in-vivo tracking of <sup>192</sup>Ir source during high dose rate or pulsed dose rate brachytherapy treatment was built using 1 mm thick silicon pad detectors as image sensors and knife-edge lead pinholes as collimators. With source self-images obtained from a dual-pinhole system, location of the source could be reconstructed in three dimensions in real time. The system was tested with <sup>192</sup>Ir clinical source (kerma rate in air at 1 m 2.38 Gy/h) in air and plexi-glass phantom. The locations of the source were tracked from a distance of 40 cm in a field of view of 20 × 20 × 20 cm<sup>3</sup>. Reconstruction precision, defined as the average distance between true and reconstructed source positions, with data collected in less than 1 s with 22 GBq <sup>192</sup>Ir source was about 5 mm. The reconstruction precision was in our case mainly limited by imperfect alignment of detectors and pinholes. With perfect alignment the statistical error would allow precision of about 1 mm which could further be improved with larger detector placed at larger distance from the pinhole. However already the modest precision of few millimeters is sufficient for in-vivo detection of larger deviations from planned treatment caused by various misadministrations or malfunctioning of the brachytherapy treatment apparatus. Usage of silicon detectors offers a possibility for building a compact device which could be used as an independent online quality assurance system. In this paper details about sensors, readout system and reconstruction algorithm are described. Results from measurements with clinical source are presented.
IEEE Transactions on Nuclear Science 11/2011; · 1.45 Impact Factor
-
I. Mandic,
F. Ravotti,
M. Glaser,
I. Sersa,
J. Hartert,
S. Franz,
V. Cindro,
I. Dolenc,
A. Gorisek,
G. Kramberger,
M. Mikuz
[show abstract]
[hide abstract]
ABSTRACT: Voltage measurement at a given forward current in dedicated dosimetric diodes is used to monitor displacement damage in silicon caused by energetic hadrons in the LHC experiments. The diodes operate in a strong magnetic field which influences their performance. In this work, measurements of the effect of the magnetic field on two types of devices: high sensitivity CMRP diodes and commercial BPW34F silicon p-i-n diodes are presented. Our results show that the magnetic field effects are manageable and will not significantly deteriorate the performance of the displacement damage measurements.
IEEE Transactions on Nuclear Science 07/2011; · 1.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Proton irradiation results are shown here for three different SiGe:C HBT technologies from IHP Microelectronics. High damages are observed although the transistors remain usable for their application on the Super-LHC. Considerations on the ionization and displacement effects additivity are also presented in order to validate parameterized experiments. This study shows a reasonable agreement between proton irradiations and previous gamma and neutron irradiations.
IEEE Transactions on Nuclear Science 09/2009; · 1.45 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this study we present the results of radiation hardness studies performed on three different SiGe:C BiCMOS technologies from Innovation for High Performance Microelectronics (IHP) for their application in the Super-Large Hadron Collider (S-LHC). We performed gamma, neutron and proton irradiations on the bipolar section of these technologies, in order to consider ionization and atomic displacement damage on electronic devices. Results show that transistors from the IHP BiCMOS technologies remain functional after the radiation levels expected in the inner detector (ID) of the ATLAS Upgrade experiment. These technologies are one of the candidates to constitute the analog part of the Front-End chip in the ATLAS-upgrade experiment, in the S-LHC.
IEEE Transactions on Nuclear Science 09/2009; · 1.45 Impact Factor
-
E. Tuominen,
P. Anbinderis,
T. Anbinderis,
R. Bates,
W. de Boer,
E. Borchi,
M. Bruzzi,
C. Buttar,
W. Chen,
V. Cindro, [......],
C. Parkes,
K. Piotrzkowski,
S. Pirollo,
P. Pusa,
J. Raisanen,
E. Tuovinen,
J. Vaitkus,
E. Verbitskaya,
S. Vayrynen,
M. Zavrtanik
[show abstract]
[hide abstract]
ABSTRACT: CERN RD39 Collaboration develops radiation-hard cryogenic silicon detectors. Recently, we have demonstrated improved radiation hardness in novel Current Injected Detectors (CID). For detector characterization, we have applied cryogenic Transient Current Technique (C-TCT). In beam tests, heavily irradiated CID detector showed capability for particle detection. Our results show that the CID detectors are operational at the temperature -50degC after the fluence of 1 times 10<sup>16</sup> 1 MeV neutron equivalent/cm<sup>2</sup>.
IEEE Transactions on Nuclear Science 09/2009; · 1.45 Impact Factor
-
J. S. Rice,
M. Ullan,
G. Brooijmans,
J. D. Cressler,
D. Damiani,
S. Diez,
T. Gadfort,
A. A. Grillo,
R. Hackenburg,
G. Hare, [......],
S. Phillips,
S. Rescia,
H. F. F-W. Sadrozinski,
A. Seiden,
N. Spencer,
H. Spieler,
A. K. Sutton,
Y. Tazawa,
E. Wulf,
M. Wilder
[show abstract]
[hide abstract]
ABSTRACT: An assessment of the radiation tolerance of the latest generation IBM silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technologies (SiGe 8WL and SiGe 8HP) at extreme dose/fluence is reported. These BiCMOS technologies are of great interest for analog readout circuits in high energy physics detectors, especially the planned upgrade of the ATLAS detector for the upgraded Large Hadron Collider (sLHC) in Geneva, Switzerland. These third-generation, 130 nm SiGe HBTs show promise to operate at lower power than CMOS circuits provided that they can be shown to be sufficiently radiation tolerant. This study presents evidence of the radiation tolerance of these two candidate technologies with parametric measurements after irradiation up to a fluence of 10<sup>16</sup> 1 MeV equivalent neutrons/cm<sup>2</sup> and a gamma dose of 100 Mrad (SiO2).
Nuclear Science Symposium Conference Record, 2008. NSS '08. IEEE; 11/2008
-
[show abstract]
[hide abstract]
ABSTRACT: Detectors and electronics inside the ATLAS detector at the large hadron collider will be exposed to high fluxes of photons, charged particles, and neutrons. Damage caused by radiation will influence the performance of the detector. It will therefore be important to continuously monitor the radiation dose to follow the level of detector degradation. It will also be important to have information about the radiation field in the detector early in the life of the experiment in order to check the simulations and to correctly predict future radiation damage. An online radiation monitoring system with semiconductor radiation sensors will monitor the dose at several locations in the ATLAS detector. It will measure ionizing dose in SiO with RadFETs, displacement damage in silicon in terms of 1-MeV(Si) equivalent neutron fluence with p-i-n diodes and fluence of thermal neutrons from current gain degradation in dedicated bipolar transistors. The design of the system and its response to various types of radiation is described.
IEEE Transactions on Nuclear Science 09/2007; · 1.45 Impact Factor
-
Z. Li,
M. Abreu,
P. Anbinderis,
T. Anbinderis,
N. U. Ambrosio,
W. Boer de,
E. Borchi,
K. Borer,
M. Bruzzi,
S. Buontempo, [......],
G. Ruggiero,
K. Smith,
P. Sonderegger,
P. Sousa,
E. Tuominen,
E. Tuovinen,
E. Verbitskaya,
J. Vaitkus,
E. Wobst,
M. Zavrtanik
[show abstract]
[hide abstract]
ABSTRACT: Radiation hardness up to 10(16) n(eq)/cm(2) is required in the future HEP experiments for most inner detectors. However, 10(16) n(eq)/cm(2) fluence is well beyond the radiation tolerance of even the most advanced semiconductor detectors fabricated by commonly adopted technologies: the carrier trapping will limit the charge collection depth to an effective range of 20-30 mu m regardless of depletion depth. Significant improvement of the radiation hardness of silicon sensors has been taken place within RD39. Fortunately the cryogenic tool we have been using provides us a convenient way to solve the detector charge collection efficiency (CCE) problem at SLHC radiation level (10(16) n(eq)/cm(2)). There are two key approaches in our efforts: (1) use of the charge/current injection to manipulate the detector internal electric field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range (<= 230K); and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the LN2 temperature. In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures. In this approach, we intend to study the trapping effect at temperatures below LN2 temperature. A freeze-out of trapping can certainly help in the development of ultra-radiation hard Si detectors for SLHC. A detector CCE measurement system using ultra-fast picosecond laser with a He cryostat has been built at CERN. This system can be used to find out the practical cryogenic temperature range that can be used to freeze out the radiation-induced trapping levels, and it is ready for measurements on extremely heavily irradiated silicon detectors. Initial data from this system will be presented. (c) 2007 Elsevier B.V. All rights reserved.
Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment. 01/2007; 579(2):775-781.
-
Z. Li,
M. Abreu,
P. Anbinderis,
T. Anbinderis,
N. D'Ambrosio,
W. Boer de,
E. Borchi,
K. Borer,
M. Bruzzi,
S. Buontempo, [......],
G. Ruggiero,
K. Smith,
P. Sonderegger,
P. Sousa,
E. Tuominen,
E. Tuovinen,
E. Verbitskaya,
J. Vaitkus,
E. Wobst,
M. Zavrtanik
[show abstract]
[hide abstract]
ABSTRACT: There are two key approaches in our CERN RD 39 Collaboration efforts to obtain ultra-radiation-hard Si detectors: (1) use of the charge/current injection to manipulate the detector internal electric field in such a way that it can be depleted at a modest bias voltage at cryogenic temperature range (<= 150 K), and (2) freezing out of the trapping centers that affects the CCE at cryogenic temperatures lower than that of the liquid nitrogen (LN2) temperature. In our first approach, we have developed the advanced radiation hard detectors using charge or current injection, the current injected diodes (CID). In a CID, the electric field is controlled by injected current, which is limited by the space charge, yielding a nearly uniform electric field in the detector, independent of the radiation fluence. In our second approach, we have developed models of radiation-induced trapping levels and the physics of their freezing out at cryogenic temperatures. (c) 2006 Elsevier B.V. All rights reserved.
Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment. 01/2007; 572(1):305-310.
-
[show abstract]
[hide abstract]
ABSTRACT: Trapping times of drifting electrons and holes were measured in high resistivity standard, oxygenated and magnetic Czochralski p-type materials with charge correction method. Diodes were irradiated with neutrons up to equivalent fluence Phi = 3 times 10<sup>14</sup> cm<sup>-2</sup>. Trapping times were parameterized as 1/tau = betaPhi. Average beta was measured to be beta<sub>e</sub> = 4.2 times 10<sup>-16</sup> cm<sup>2</sup> ns<sup>-1</sup> for electrons and beta<sub>h</sub> = 4.3 times 10<sup>-16</sup> cm<sup>2</sup> ns<sup>-1</sup> for holes.
Nuclear Science Symposium Conference Record, 2006. IEEE; 12/2006
-
[show abstract]
[hide abstract]
ABSTRACT: In this work we analyzed the radiation hardness of SiC p<sup>+</sup> n diodes used as minimum ionizing particle (MIP) detectors after very high 1 MeV neutron fluences. The diode structure is based on ion implanted p<sup>+</sup> emitter in an n-type epilayer with thickness equal to 55 μm and donor doping N<sub>D</sub>=2× 10<sup>14</sup>cm<sup>-3</sup>. The diode breakdown voltages were above 1000 V. At 1000 V the leakage currents are of the order of 1 nA for all the measured diodes. The full depletion voltage is near 220-250 V. The charge collection efficiency to minimum ionizing particle has been investigated by a <sup>90</sup>Sr β source. At 250 V the collected charge of the unirradiated diodes saturates near 3000 e<sup>-</sup>. At bias voltages over 100 V the energy spectrum of the collected charge was found to consist of a signal peak well separated from the noise. At around 250 V the signal saturates, in agreement with CV results. These devices have been irradiated at 6 different fluences, logarithmically distributed in the range 10<sup>14</sup>-10<sup>16</sup> (1 MeV) neutrons/cm<sup>2</sup>. The leakage current after irradiation decreases. The collected charges decrease for increasing fluences, remaining very high only until some 10<sup>14</sup> n/cm<sup>2</sup>.
IEEE Transactions on Nuclear Science 07/2006; · 1.45 Impact Factor
-
M. Mikuz,
V. Cindro,
I. Dolenc,
H. Kagan,
G. Kramberger,
H. Frais-Kolbl,
A. Gorisek,
E. Griesmayer, I. Mandic,
H. Pernegger,
W. Trischuk,
P. Weilhammer,
M. Zavrtanik
[show abstract]
[hide abstract]
ABSTRACT: The ATLAS beam conditions monitor is being developed as a stand-alone device allowing to separate LHC collisions from background events induced either on beam gas or by beam accidents, for example scraping at the collimators upstream the spectrometer. This separation can be achieved by timing coincidences between two stations placed symmetric around the interaction point. The 25 ns repetition of collisions poses very stringent requirements on the timing resolution. The optimum separation between collision and background events is just 12.5 ns implying a distance of 3.8 m between the two stations. 3 ns wide pulses are required with 1 ns rise time and baseline restoration in 10 ns. Combined with the radiation field of 10<sup>15</sup> cm<sup>-2</sup> in 10 years of LHC operation only diamond detectors are considered suitable for this task. pCVD diamond pad detectors of 1 cm<sup>2</sup> and around 500 μm thickness were assembled with a two-stage RF current amplifier and tested in proton beam at MGH, Boston and SPS pion beam at CERN. To increase the S/N ratio two back-to-back diamonds were read out by a single amplifier and the detectors inclined to 45 degrees. Limiting the bandwidth at the readout to 200 MHz provided further improvement; S/N ratio of nearly 10:1 could be achieved with MIP's. Amplifiers of the two stages were irradiated with protons and neutrons to 10<sup>15</sup> cm<sup>-2</sup>. Evaluating the irradiated electronics with silicon pad detectors, 20% degradation in S/N ratio was observed. Ten detector modules are being assembled and tested at CERN for their final installation into the ATLAS pixel support structure in the beginning of 2006.
Nuclear Science Symposium Conference Record, 2005 IEEE; 11/2005
-
M. Bruzzi,
J. Adey,
A. Al-Ajili,
P. Alexandrov,
G. Alfieri,
P P Allport,
A Andreazza,
M. Artuso,
S. Assouak,
B.S. Avset, [......],
I Wilhelm,
S Worm,
V. Wright,
R Wunstorf,
P. Zablerowski,
A. Zaluzhny,
M. Zavrtanik,
M. Zen,
V Zhukov,
N. Zorzi
[show abstract]
[hide abstract]
ABSTRACT: An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 1035 cm-2 s-1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 1016cm-2. The CERN-RD50 project "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit. The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work. 2005 Published by Elsevier B.V.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 05/2005; 541:189-201. · 1.21 Impact Factor
-
M. Moll,
J. Adey,
A. Al-Ajili,
G. Alfieri,
P P Allport,
M. Artuso,
S. Assouak,
B.S. Avset,
L. Barabash,
A. Barcz, [......],
S Worm,
V. Wright,
R Wunstorf,
Y. Yiuri,
P. Zabierowski,
A. Zaluzhny,
M. Zavrtanik,
M. Zen,
V Zhukov,
N. Zorzi
[show abstract]
[hide abstract]
ABSTRACT: The envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 10(35) cm(-2) s(-1) Will present severe challenges for the tracking detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10 ns as well as the need for cost effective detectors have called for an intensive R&D program. The CERN RD50 collaboration "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" is working on the development of semiconductor sensors matching the requirements of the SLHC. Sensors based on defect engineered silicon like Czochralski, epitaxial and oxygen enriched silicon have been developed. With 3D, Semi-3D and thin detectors new detector concepts have been evaluated and a study on the use of standard and oxygen enriched p-type silicon detectors revealed a promising approach for radiation tolerant cost effective devices. These and other most recent advancements of the RD50 collaboration are presented. (c) 2005 Elsevier B.V. All rights reserved.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 05/2005; 546:99-107. · 1.21 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In 10 years of operation in the CMS electromagnetic calorimeter (ECAL), avalanche photodiodes will be exposed to 1 MeV equivalent neutron fluence of 2·10<sup>13</sup> n/cm<sup>2</sup> and total ionization dose of 0.25 Mrad. These APDs are silicon photodiodes operated in avalanche mode. To explore the possibility of usage of these APDs in harsher radiation environments, they were irradiated with reactor neutrons up to 1 MeV equivalent fluence of 5·10<sup>14</sup> n/cm<sup>2</sup>. This paper reports on measurements of current-voltage characteristics and scan of surface uniformity after irradiation.
Nuclear Science Symposium Conference Record, 2004 IEEE; 11/2004
-
[show abstract]
[hide abstract]
ABSTRACT: DMILL bipolar transistors (npn) were exposed to 24 GeV protons and fast and thermal neutrons to fluences up to 6·10<sup>14</sup> n/cm<sup>2</sup>. Transistor common emitter current gain (β=I<sub>collector</sub>/I<sub>base</sub>) was measured after irradiations. It was found that β degradation scales as Δ(1/β)=k<sub>T</sub>·Φ<sub>T</sub> where Φ<sub>T</sub> is the fluence of thermal neutrons and as Δ(1/β)=k<sub>eq</sub>·Φ<sub>eq</sub>, with Φ<sub>eq</sub> 1-MeV equivalent fluence, if transistors are irradiated with protons or fast neutrons. Large damage factor k<sub>T</sub>∼3·k<sub>eq</sub> was measured. Thermal neutrons do not have sufficient energy to displace a Si atom. Their damage mechanism is, therefore, identified with <sup>10</sup>B(n,α)<sup>7</sup>Li reaction from which energetic α and Li particles produce bulk damage in the base of the device. Boron is used as the base dopant in these transistors having also highly doped regions below base contacts. Irradiations with neutrons with energies distributed from thermal to fast show that gain degradation adds up as Δ(1/β)=k<sub>T</sub>·Φ<sub>T</sub>+k<sub>eq</sub>·Φ<sub>eq</sub>.
IEEE Transactions on Nuclear Science 09/2004; · 1.45 Impact Factor
-
T.O Niinikoski,
M Abreu,
P Anbinderis,
T Anbinderis,
N D'Ambrosio,
W de Boer,
E Borchi,
K Borer,
M Bruzzi,
S Buontempo, [......],
P Sousa,
E Tuominen,
E Tuovinen,
J Vaitkus,
E Verbitskaya,
C da Viá,
L Vlasenko,
M Vlasenko,
E Wobst,
M Zavrtanik
[show abstract]
[hide abstract]
ABSTRACT: RD39 collaboration develops new detector techniques for particle trackers, which have to withstand fluences up to of high-energy particles. The work focuses on the optimization of silicon detectors and their readout electronics while keeping the temperature as a free parameter. Our results so far suggest that the best operating temperature is around . We shall also describe in this paper how the current-injected mode of operation reduces the polarization of the bulk silicon at low temperatures, and how the engineering and materials problems related with vacuum and low temperature can be solved.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 01/2004;
-
J. Harkonen,
M. Abreu,
P. Anbinderis,
T. Anbinderis,
N. D'Ambrosio,
W. Boer de,
E. Borchi,
K. Borer,
M. Bruzzi,
S. Buontempo, [......],
P. Sousa,
E. Tuominen,
E. Tuovinen,
J. Vaitkus,
E. Verbitskaya,
C. Da Via,
L. Vlasenko,
M. Vlasenko,
E. Wobst,
M. Zavrtanik
[show abstract]
[hide abstract]
ABSTRACT: The CERN RD39 Collaboration is developing super-radiation hard cryogenic Si detectors for applications in experiments of the LHC and the future LHC Upgrade. Radiation hardness up to the fluence of 10(16)n(eq)/cm(2) isrequired in the future experiments. Significant improvement in the radiation hardness of silicon sensors has taken place during the past years. However, 10(16) n(eq)/cm(2) is well beyond the radiation tolerance of even the most advanced semiconductor detectors made by commonly adopted technologies. Furthermore, at this radiation load the carrier trapping will limit the charge collection depth to the range of 20-30mum regardless of the depletion depth. The key of our approach is freezing the trapping that affects Charge Collection Efficiency (CCE). (C) 2004 Elsevier B.V. All rights reserved.
Nuclear Instruments & Methods in Physics Research Section a-Accelerators Spectrometers Detectors and Associated Equipment. 01/2004; 535(1-2):384-388.
-
[show abstract]
[hide abstract]
ABSTRACT: DMILL bipolar transistors (npn) were exposed to thermal and fast neutrons to fluences up to 6·10<sup>14</sup> n/cm<sup>2</sup>. Transistor common emitter current gain (β = I<sub>collector</sub>/I<sub>base</sub>) was measured after irradiations. It was found that beta degradation scales as Δ1/β = k<sub>T</sub>·Φ<sub>T</sub> where Φ<sub>T</sub> is the fluence if transistors are irradiated with thermal neutrons and as Δ1/β = K<sub>eq</sub>·Φ<sub>eq</sub>, where Φ<sub>eq</sub> is 1 MeV equivalent fluence if transistors are irradiated with fast neutrons behind Cd shield. Large damage factor K<sub>T</sub> ∼ 3·K<sub>eq</sub> was measured. Thermal neutrons don't have sufficient energy to displace a Si atom. Their damage mechanism is therefore identified with <sup>10</sup>B(n, α)<sup>7</sup>Li reaction from which energetic α and Li particles produce damage in the base of the device. Boron is used as the base dopant in these transistors having also highly doped regions below base contacts.
Nuclear Science Symposium Conference Record, 2003 IEEE; 11/2003
-
I. Mandic
[show abstract]
[hide abstract]
ABSTRACT: The ABCD3TA readout chip for silicon strip detectors of the ATLAS SemiConductor Tracker (SCT) is described. It is the final design of the single chip implementation of the binary readout architecture. The chip is manufactured in the DMILL radiation-hardened BiCMOS process. Summary of results of irradiations of ABCD3TA chips with up to 100 kGy and 2×10<sup>14</sup> n/cm<sup>2</sup> (1-MeV neutron NIEL equivalent) done with various sources is given in this paper. Measurements of single event effects with high-energy proton and pion beams are also reported. The tests proved that the chips are sufficiently radiation hard for application in the ATLAS SCT.
IEEE Transactions on Nuclear Science 01/2003; · 1.45 Impact Factor
