Giulio Villani 20/11/2002 8th Topical Seminar on Innovative Particle and Radiation Detectors Siena, 21 – 24 October 2002 Giulio Villani 20/11/2002

SIENA is located in Tuscany about 50km south of Florence Ancient Etruscan settlement, became Roman colony under the name of Sena Julia Its importance grew in Middle Ages until became a municipality in 12th century: flourished in XIV century Frequent confrontations with neighbouring towns: taken over by Florence in 16th century Still retains an authentic medieval atmosphere

Piazza del Campo 14th century, is the heart of the city Location of the ancient roman forum, boasts 14th century gothic buildings Palazzo pubblico e Torre del mangia Fonte Gaia by Jacopo della Quercia The horse race (Palio) is held here, 2nd of July and 16th of August Of medieval origin, sees the 10 of the 17 contrade competing against each other: the winner gets the Palio (banner)

The Dome,XIV century: one of the best roman-gothic architectural examples Masterpieces by Nicola Pisano, Donatello,Pinturicchio Floor consisting of 56 different mosaics, depicting sacred scenes, required more than 150 years to be completed

High Energy Neutrino Astronomy Giulio Villani 20/11/2002 High Energy Neutrino Astronomy Christian Spiering, Siena, October 2002 Giulio Villani 20/11/2002

Physics Goals A. High Energy Neutrino Astrophysics B. Particle Physics Giulio Villani 20/11/2002 Physics Goals A. High Energy Neutrino Astrophysics Weakly interacting neutrinos reach us from very distant sources: possible invaluable instrument for high-energy astrophysics B. Particle Physics Magnetic Monopoles, Oscillations, Neutrino Mass ... C. Others Supernova Bursts, CR composition, Black Holes, ... Giulio Villani 20/11/2002

Cosmic Rays 1 TeV GZK cut-off

up to 1-10 PeV Crab nebula Supernova shocks expanding in interstellar medium up to 1-10 PeV Crab nebula

Active Galaxies: accretion disk and jets up to 1020 eV VLA image of Cygnus A

Underwater Air showers Underground Radio,Acoustic pp core AGN p blazar jet log(E2  Flux) Top-down WIMPs Oscillations GZK GRB (W&B) Microquasars etc. 3 6 9 log(E/GeV) TeV PeV EeV

Diffuse Fluxes: Predictions and Bounds Mannheim & Learned, 2000 1 pp core AGN (Nellen) 2 p core AGN Stecker & Salomon) 3 p „maximum model“ (Mannheim et al.) 4 p blazar jets (Mannh) 5 p AGN (Rachen & Biermann) 6 pp AGN (Mannheim) 7 GRB (Waxman & Bahcall) 8 TD (Sigl) 9 GZK Macro Baikal Amanda 9

Detection Methods and Projects Giulio Villani 20/11/2002 Detection Methods and Projects Underwater/Ice Cerenkov Telescopes Acoustic Detection Radio Detection Detection by Air Showers Giulio Villani 20/11/2002

Underwater/Ice Cerenkov Telescopes Giulio Villani 20/11/2002 Strings of widely spaced PMT put in deep water 4-string stage (1996) AMANDA: Antarctic Muon And Neutrino Detector Array Giulio Villani 20/11/2002

Cerenkov radiation in H2O : v0.75c,  = tg-1[(n2 v2/c2-1)1/2] High-energy neutrinos through the earth may interact and create muons which emit Cherenkov light muon cascade

 resolution Amanda-B10 ~ 3.5° 1 km 2 km SPASE air shower arrays  resolution Amanda-B10 ~ 3.5° results in ~ 3° for upward moving muons (Amanda-II: < 2°)

AMANDA Amanda-II: 677 PMTs at 19 strings (1996-2000) 80PMTs Super-K DUMAND Amanda-II: 677 PMTs at 19 strings (1996-2000) AMANDA-II

Point Sources Amanda II (2000) 1328 events Preliminary limits (in units of 10-15 muons cm-2 s-1): Cas A: 0.6 Mk421: 1.4 Mk501: 0.8 Crab: 6.8 SS433: 10.5

Expected sensitivity AMANDA 97-02 data m  cm-2 s-1 southern sky northern sky 4 years Super-Kamiokande 10-14 170 days AMANDA-B10 8 years MACRO SS-433 10-15 Expected sensitivity AMANDA 97-02 data Mk-421 / ~ 1 -90 -45 90 45 declination (degrees)

IceCube - 80 Strings - 4800 PMT Instrumented volume: 1 km3 AMANDA South Pole IceTop IceCube - 80 Strings - 4800 PMT Instrumented volume: 1 km3 Installation: 2004-2010 ~ 80.000 atm. per year

mediterraneum Mediterranean Projects 2400m ANTARES 4100m 3400m NEMO NESTOR

Site: Pylos (Greece), 3800m depth towers of 12 titanium floors each supporting 12 PMTs

40 km Submarine cable - 2400 m

ANTARES Design 10 strings 12 m between storeys Shore station float active Electro-optic submarine cable ~40km Junction box Readout cables Shore station anchor float Electronics containers ~60m Compass, tilt meter hydrophone Optical module Acoustic beacon ~100m 10 strings 12 m between storeys

NEMO Neutrino Mediterranean Observatory abs. length ~70 m 80 km from coast 3400 m deep

Summer 2002 Deployment 2 floors NESTOR 1991 - 2000 R & D, Site Evaluation Summer 2002 Deployment 2 floors Winter 2003 Recovery & re-deployment with 4 floors Autumn 2003 Full Tower deployment 2004 Add 3 DUMAND strings around tower 2005 - ? Deployment of 7 NESTOR towers ANTARES 1996 - 2000 R&D, Site Evaluation 2000 Demonstrator line 2001 Start Construction September 2002 Deploy prototype line December 2004 10 (12?) line detector complete 2005 - ? Construction of km3 Detector NEMO 1999 - 2001 Site selection and R&D 2002 - 2004 Prototyping at Catania Test Site 2005 - ? Construction of km3 Detector

R Suitable for UHE Threshold > 10 PeV d ACOUSTIC DETECTION 50s Particle shower  ionization  heat  perpendicular pressure wave Maximum of emission at ~ 20 kHz d R P t 50s Attenuation of sea water → given a large initial signal, huge detection volumes can be achieved.

AUTEC array in Atlantic existing sonar array for submarine detection Atlantic Undersea Test and Evaluation Center 52 sensors on 2.5 km lattice (250 km2) 4.5 m above surface 1-50 kHz ! Threshold ~ 100 EeV

RADIO DETECTION: Askaryan process Interaction in ice:e + n  p + e- e-  ... cascade  relativist. pancake ~ 1cm thick,  ~10cm  each particle emits Cherenkov radiation  C signal is resultant of overlapping Cherenkov cones Coherent Cherenkov signal for  >> 10 cm (radio)  C-signal ~ E2 nsec Compton scattered electrons  shower develops negative net charge Qnet ~ 0.25 Ecascade (GeV). Threshold > 10 PeV

South Pole E 2 · dN/dE < 10-4 GeV · cm-2 · s-1 · sr-1 Showers in RF-transparent media (ice, rock salt) RICE Radio Ice Cherenkov Experiment South Pole firn layer (to 120 m depth) 20 receivers + transmitters UHE NEUTRINO     DIRECTION E 2 · dN/dE < 10-4 GeV · cm-2 · s-1 · sr-1 at 100 PeV 300 METER DEPTH

AntarcticImpulsiveTransientArray Flight in 2006

Extensive Air Showers for E > 10 EeV produce Ionization trails Far inclined showers ( thousand per year) Hard  s Atmosphere Flat and thin shower front Narrow signals Time alignment Deep inclined showers (~ one per year?) Atmosphere Soft  s + e.m. Curved and thick shower front Broad signals el.-magn. cascade from e hard muons from CR Extensive Air Showers for E > 10 EeV produce Ionization trails

Need an observation from above (satellite) Observation of upward going optical Cherenkov radiation emitted by tau neutrino -induced air-showers Need an observation from above (satellite)

Horizontal Air Showers seen by Satellite 500 km 60 ° E > 1019 eV Area up to 106 km2 Mass up to 10 Tera-tons Horizontal air shower initiated deep in atmosphere 1 - 20 GZK ev./y

OWL Orbiting Wide-angle Light-collectors Extreme Universe Space Observatory OWL Orbiting Wide-angle Light-collectors

RICE AGASA Amanda, Baikal 2002 2004 GLUE AUGER nt Anita AABN 2007 2012 km3 EUSO Auger Salsa

Most promising: point sources Conclusions Most promising: point sources 0.1 km3 and 1 km3 detectors underwater and ice Huge step in GZK region Exciting decade ahead Contacts: Christian Spiering csspier@ifh.de

Solar Neutrino Spectrometer with InP Detectors P.G. Pelfer University of Florence and INFN, Firenze, Italy F. Dubecky Institute of Electrical Engineering, Slovak Academy of Sciences Bratislava, Slovakia A.Owens ESA/ESTEC Noordwijk,Netherland

Why InP Solar Neutrino Experiment ? Giulio Villani 20/11/2002 Why InP Solar Neutrino Experiment ? Semi Insulating InP Material base material for: Hard X-Ray Detectors Fast Electronics and Optoelectronics InP Spectrometer, the Smallest, Real Time, Lower Energy pp Solar Neutrino Spectrometer The Solar Neutrino Spectrometer from/for R&D on InP X-Ray Detectors ? Giulio Villani 20/11/2002

DETECTOR APPLICATIONS Giulio Villani 20/11/2002 DETECTOR APPLICATIONS BASIC KNOWLEDGE Solar Neutrino Physics X-ray astronomy X-ray physics MEDICINE Digital X-ray radiology (stomatology, mammography, ...) Positron emission tomography Dosimetry NONDESTRUCTIVE ON-LINE PROCESS CONTROL Material defectoscopy MONITORING Environmental control Radioactive waste management Metrology (testing of radioactive sources, spectrometry...) NATIONAL SECURITY Contraband inspections: cargo control Detection of drugs and plastic explosives Cultural heritage study Giulio Villani 20/11/2002

Requirements for Hard X-Ray Detectors of the New Generation >10keV Room temperature (RT) operation Portability Fast reaction rate Universal detection ability Good detection parameters: CCE, FWHM, DE Radiation hardness Well established material technology Well established device technology (10 m) FE Electronics and Optoelectronics integration on the Detector LOW COST RT OPERATION: EG > 1.2 eV POLARISATION EFFECT: EG < 2.5 eV HIGH ENERGY RESOLUTION: EG small HIGH STOPPING POWER: Z > 30 HIGH CARRIER MOBILITY: > 2000 cm2/Vs CANDIDATES CdTe, HgI2, GaAs, InP

Attenuation and mobility Giulio Villani 20/11/2002 Attenuation and mobility Giulio Villani 20/11/2002

Neutrino from the Sun Water Kamioka, SuperK x + e-  x + e- (ES) Gallium SAGE, Gallex, GNO e + 71Ga  71Ge + e- Chlorine Homestake e + 37Cl  37Ar + e- D2O SNO x + e-  x + e- (ES) e + d  p + p + e- (CC) x + d  n + p + e- (NC)

Giulio Villani 20/11/2002 Giulio Villani 20/11/2002

Requirements for Indium Solar Neutrino Spectrometer Giulio Villani 20/11/2002 Requirements for Indium Solar Neutrino Spectrometer 1. Indium incorporated into the detector 2. Energy resolution ∆E/E of the order of 25% at 600 keV. Important for spectrometry as well as background reduction. 3. Time resolution of the order of 100 ns for ~ 100 keV radiations. 4. Position resolution ∆V/V  10-7 at a reasonable cost. Very important for background reduction 5. Good energy resolution for low energy radiations ( ~ 50 keV ) 6. Made with materials of high radiactive purity Giulio Villani 20/11/2002

Neutrino Detection by In Target Giulio Villani 20/11/2002 Neutrino Detection by In Target 1/2= 4.76  sec 7/2+ 612.81 keV e 9/2+ 1 3/2+ 497.33 keV 115In (95.7%) - 2 1/2=6x1014 y 1/2+ 115Sn E    e(E - 118 keV ) + 115 Sn*   Delay  = 4.76  sec   115Sn*  115Sn + e-(88  112 keV)/1 (115.6 keV) +  2(497.33 keV) Giulio Villani 20/11/2002

Solar Neutrino Event in InP Detector Giulio Villani 20/11/2002 “ delayed event “ in a 27 cm3 macrocell Solar Neutrino Event in InP Detector " prompt event “ in a “1 cm3 cell” 3 4 5 2 2 1 6 1 3 4 5 9 8 7 time 2 1 6 e 9 8 7 10 s 1 cm3 cell Detector made up of many ‘basic cells’ 106 InP “1 cm3 cell” Calorimeter Module Giulio Villani 20/11/2002

FULL NEUTRINO SPECTROMETER Spectrometer Building Block Nmodules  125 Spectrometer Module 100 mm 200 mm Pad Detectors V microcell  1 mm3 N microcell /cm3  1000 1 neutrino event once a day for 1011 background events

SemiInsulating InP Wafer Neutrino Spectrometer 6” diameter, 1 mm thick Pad Detectors Basic Component of Neutrino Spectrometer Present InP Material and Detector Technology

SI InP Material and Detector Technology Producer: JAPAN ENERGY Co., Japan Growth Technique: LEC High-Temperature Wafer Annealing Resistivity (300 K): 4.9x107 cm Hall Mobility (300K): 4410 cm2/Vs Fe Content: 2x1015 cm-3 Orientation: <100> Final Wafer Thickness: ~ 200 m Original BUFFERS realised using ion implantation in backside (PATENTED) Symmetrical circular contact configuration, 2mm  , using both-sided photolithography Final metallisation: TiPtAu on top and AuGeNi on backside Surface passivation by Silicon Nitride

InP Detector Test Setup 3.142 mm2 x 200 m

Energy Resolution vs Shaping Time and Spectral Response in InP Laboratory Measurements E=2.4 keV at 5.9 keV : 8.5 keV at 59.54 keV

Linearity and Resolution vs X Ray Energy in InP Laboratory Measurements

InP Spatial Distributions The detectors spatial response measured at HASYLAB using a 50  50 m2, 15 keV X-ray beam. InP Spatial Distributions contact bond wire Count rate Peak centroid Resolving power

Summary and Conclusions Giulio Villani 20/11/2002 Summary and Conclusions Present Radiation Detectors based on Bulk SI InP Fe doped have very good Detection Parameters for the X ray Detection from HASYLAB SR Facilty FWHM from 2.5 KeV at 5.9 KeV to 5.5 KeV at 100 KeV DE 10% at 100 KeV for 200 m thick Detector due to Better Material from Japan Energy and to Improved Interface Technology Some Problems for Detector Polarisation Detectors performances good for Solar Neutrino Spectrometer Optimisation is our next research goal Contacts: Pier Giovanni.Pelfer pelfer@fi.infn.it Giulio Villani 20/11/2002

Application of nanotechnologies in High Energy Physics Giulio Villani 20/11/2002 Application of nanotechnologies in High Energy Physics A.Montanari, F.Odorici INFN Bologna & Bologna University Italy Giulio Villani 20/11/2002

Nanotechnologies characteristics Technologies for processing material on a nanometric scale: 1-100nm Interests in many field of research: biology, chemistry, nanoelectronic,science of material Nano-objects very attractive also in terms of application to a new generation of position particle detectors Mask, dies Contacts, probes Nano-holes, nanochannels Nano-wires, nanotubes

Nanotubes introduction Single-Wall Carbon Nanotubes (SWNT) discovered in 1991 Essentially long thin cylinders of carbon

price list from Bucky USA website buckyusa@flash.net Single-wall nanotubes are formed in a carbon arc in the presence of a metal catalyst.  The tubes are found in the matted soot deposited on the reaction chamber wall  low yield The As-Produced Soot contains tubes that are 0.7-1.2 nm in diameter and 2-20 µm in length.  The product contains 10-40% tubes, the remainder is carbon-coated metal nanoparticles and amorphous and carbon nanoparticles price list from Bucky USA website buckyusa@flash.net

SWNT are truly 1D objects NT can have very broad range of electrical, optical, mechanical, thermal characteristics depending on their geometrical properties (diameter, length and chirality) SWNT are truly 1D objects Beside SWNT it is possible to grow Multiple Walls Nano Tubes (MWNT) Energy gap dependency on diameter and chirality Quantum conductance of MWNT G0 = 2e2/h 1/12.9 k -1

Nanotransistor FET using NT as channel NT applications Nanotransistor FET using NT as channel Microphotograph from IBM website At low temperature, it becomes a Single Electron Transistor (SET)

FIELD EMISSION FROM ARRAYS OF CARBON NANOTUBES The aligned Nanotube field emitter are grown on a silicon substrate, by CVD Nanotubes array grown by CVD 20 left 2  right 1  separation min from NanoLab website

2 atoms crystal KI within 1.4nm SWNT Peculiar properties expected by the nanodimensions associated with NT filling: Superconductive phenomena (reported for K,Rb,Cs) at rel. high temp 50K TEM image of KI@SWNT hybrid material 2 atoms crystal KI within 1.4nm SWNT

New concept: bundles of NT used for position detectors Readout electronics Radiation Filling of nanotubes already possible Nanopixel detector

Require uniform and reproducible structure: using catalysts in chemical vapour deposition straight nanotubes are possible Anodization of iperpure Aluminum sheets (100-300 mm thick ) under controlled conditions produces an oxide (Al2 O3 , Alumina) with self-organized regular honeycomb structure The size and pitch of nanochannels depend on the parameters of the process (voltage, acid type, acid concentration, temperature): Pitch: 40 -> 400 nm

· Alumina nanochannels used to grow nanotubes Alumina nanochannels can be used to grow CNs, after the deposition of the catalyst (Ni, Fe, Co) at the bottom of each single pore Growth of CN by Chemical Vapor Deposition of a hydrocarbur at 600- 800 o C Temperature, gas concentration and duration of the process determine the CN structure (SWNT or MWNT, metallic or semiconductor)

Alumina nanochannels growing

NANO CHANNEL ACTIVE LAYER DETECTOR CONCEPT

Contacts: Alessandro.Montanari@bo.infn.it Conclusions   ·    NanoChant project (INFN & CNR) started as an R&D study aimed at improving by one order of magnitude the spatial resolution of position particle detectors, by using nanotechnologies (Carbon Nanotubes grown inside Alumina Nanochannels) Present state: building of the Alumina Nanochannels pore size 40nm pitch 100nm Immediate next step: growing of CN inside Nanochannels Future step: study of properties of CN, to optimise their use as charge collectors and their coupling to active medium Contacts: Alessandro.Montanari@bo.infn.it

Resistive Plate Chambers as thermal neutron detectors DIAMINE Collaboration WP-2 BARI, Italy M. Abbrescia, G. Iaselli, T. Mongelli, A. Ranieri, R. Trentadue, V. Paticchio

Reasons for new thermal neutron detectors The humanitarian demining problem Neutron Backscattering Technique (NBT) Metal Detectors not effective against anti- personnel mines: Neutron backscattering method: moderation of high-energy neutrons produced by radio-isotopic source or generator

Low (thermal) energy neutrons reflected from the soil is a direct indication of the amount of hydrogen The amount of hydrogen in a plastic landmine is much higher (40-65%) than that of the surrounding soil even in case this is wet A thermal neutron detector in combination with a neutron source is scanned across the soil, the presence of a landmine will be indicated by an increase in the number of thermal neutrons  

RPCs for thermal neutron detection 1) Bakelite electrodes 2) Gap: 2 mm 3) HV electrodes: graphite 100 m 4) High resistivity layer 5) Pick-up strips 6)&7) readout electronics Operating pressure: ~ 1 Atm bakelite resistivity 10 10- 10 12 cm electrodes treated with linseed oil RPCs are easy to build, mechanically robust, light-weighted, cheap, can cover large surfaces, are adapt for industrial production, etc. particularly suitable for “on-field” applications

Neutron Detection Neutrons can be revealed only after the interaction in a suitable material Production of secondary ionising particles The choice of the converter is crucial for the performance of the detector

Choice of the converter Gd Natural Gd is characterized by a thermal neutron  (50 kbarn) 12 times larger than 10B  (3840 barn) Produced electron range (15-30 m) is >than ’s (3-4 m) Beyond E=100 meV, Gd cross section decreases much more rapidly than the one of 10B E1 eV it is smaller than the one of 10B. For application concerning only thermal neutron detection Gd is preferable to 10B

Layer of the converter consists of Gd2O3 mixed with linseed oil; the mixture is sprayed onto the bakelite electrodes, which are used to build standard RPC   It is possible to obtain extremely uniform layers, with very constant thickness and density HV Gas RPCs 10x10 cm2 in dimensions one without Gd2O3, used as a reference and two with a different concentration of the oil Gd2 O3 mixture   Signal readout: copper pad Signal input to: NIM discriminator, Vthr=30 Operating voltage 10-11kV (streamer mode) gas mixture  The electric properties (surface resistivity) of bakelite electrodes are not altered

Schematic diagram of test system RPC with Gd-oil TDC2 2 layers of 10B 0.35μm U e- RPC CI TDC1 t0 start DAQ tn stop to a multihit TDC TOA of e- plus delay start signal for two multihit TDC Neutron energy computed

·     ‘raw’ data show already the higher efficiency achieved using this method Background noise (of the chamber, out of time neutrons) to be taken into account Relative efficiency of conversion: around 2.5-3 times better

Conclusions Contacts: marcello.abbrescia@ba.infn.it Demonstrated the feasibility of this approach to build Gd-RPC for thermal neutrons Both detectors have an efficiency > 2.5 eff. CI ( 6%)   RPC-Gd experimental efficiency is > 10B theoretical maximum efficiency >> 10B-RPC experimental efficiency Coupling two of these detectors together efficiency reaches about 3.5-4 eff. CI (analysis in progress) Performances of various types of detectors have been evaluated by a technical board of EC together with Monte Carlo analysis of the signal generated by a APL. Decision on when and how to really test a device is being under consideration. Contacts: marcello.abbrescia@ba.infn.it

Brunel University, London, UK Giulio Villani 20/11/2002 ADVANCES IN SEMICONDUCTOR DETECTORS FOR PARTICLE TRACKING IN EXTREME RADIATION ENVIRONMENTS Cinzia Da Via’ Brunel University, London, UK Giulio Villani 20/11/2002

SUCCESS OF THE EXPERIMENTS REQUIRE PRECISE MEASUREMENT OF INTRODUCTION PHYSICS REQUIREMENTS AT LHC AND SHLC (1035 cm2s-1) p p H b Higgs channel SUCCESS OF THE EXPERIMENTS REQUIRE PRECISE MEASUREMENT OF MOMENTUM RESOLUTION TRACK RECONSTRUCTION B-TAGGING EFFICIENCY POSSIBLE WITH SILICON, HOWEVER…

RADIATION ENVIRONMENT AT LHC AND EXPECTED AT SLHC 5*1015  5*1014

PRESENT STATUS OF RAD HARD SILICON DETECTORS NORMALLY USED IN HEP

EFFECTS OF RADIATION DAMAGE IN SILICON DETECTORS Generation of charge traps by displacement damage of bulk silicon (interstitials and vacancies) Nuclear interactions Secondary processes from energetic displaced lattice atoms Non Ionizing Energy Loss: Energy loss due to collision with lattice nuclei depends on mass of the particle

RADIATION INDUCED BULK DAMAGE

RADIATION DEFECTS AND MACROSCOPIC EFFECTS V,I mobile migrate until meet impurities and dopants to form stable defects: Charge defects: Neff,Vbias Deep traps, recombination centers: signal charge loss Generation centers: Ileak noise Oxygen-Vacancy complex forms an acceptor state in the upper half of band-gap (acts as a trapping center) Neff

MACROSCOPIC PARAMETERS CHANGES AT 1015 n/cm2

SPACE CHARGE AFTER IRRADIATION

Leff= t*Vdrift COLLECTION DISTANCE DETERMINED BY DRIFT LENGTH Also effect of charge sharing due to low field region after type inversion

MAIN DETECTORS STRATEGIES FOR SURVIVAL BEYOND 1015 n/cm2

OXYGEN AND STANDARD SILICON Defect engineering:influence the defect kinetics by incorporation of impurities Higher O content: less donor removal O VO not harmful @ room T V Vfd reduced 3 times No improvements for neutrons P VP donor removal

SHORT DRIFT LENGTH USING 3D DETECTOR

3D VERSUS PLANAR APPROACH

Contacts: Cinzia.DaVia@brunel.ac.uk CONCLUSIONS: Contacts: Cinzia.DaVia@brunel.ac.uk

Analysis and Simulation of Charge Collection in Monolithic Active Pixel Sensors (MAPS) E.Giulio Villani, Renato Turchetta, Mike Tyndel   Rutherford Appleton Laboratory

MAPS CONCEPTS AND CHARACTERISTICS R C e o a n d t o r u o t l Reset Column line Row sel Column parallel ADCs I2 C Data processing – output stage Charge generated by impinging radiation in sensitive element D diffuses towards the cathode. The related voltage variation is buffered by the source follower and transmitted further down the line once the row is selected. One row at a time is readout

P+ P Sensitive volume (2 – 20 μm thick) P++ Substrate (300 – 500 μm thick) N+ electronics  Ionisation- generated charge remains confined within the potential well in the epitaxial layer and moves by thermal diffusion towards the cathode

Typical results F  20ns Typical diffusion time for 5m active area is about 20ns, with 600e- collected (simulation performed with ISE-TCAD on device with 5m epitaxial thickness >10m substrate 2V bias) Sufficiently fast for Linear Collider: however, LHC would require faster and more radiation tolerant device

To be solved within the regions of the device New concept design and analysis: introduction of N-layer to extend electric field into active region N layer Cathode Active area To be solved within the regions of the device

Simulation results: Electric field comparison DEVICE DESIGN Simulation results: Electric field comparison NEW STANDARD

Superposition of voltage variations at the collecting cathode: new structure shows smaller swing than the standard structure but is faster regardless of the hit point τF 2ns τF 17ns Fall time τF (0 to 90% of full swing) approximately 8.5 times smaller

NEW STANDARD τF  2ns Charge collection time shows the same fast behavior with fall time τF  2ns Total capacitance C  6.63fF  

CONCLUSIONS Results of 2D simulations on standard MAPS compare favorably with what amply reported in literature         New structure proposal: analysis suggests the possibility of performances improvements        Design and simulation: results show shorter collection time and better efficiency which pave the way for improved radiation tolerance   Next steps: o     Full 3D simulation of a device with side implants o     Fabrication and test o     Implementation of readout electronics

New device structure PWy PWx DNWy X Y Z DSUB