1 / 18

SciFi 2

SciFi 2. B. Leverington, on behalf of the SciFi One group. Points for today:. I will focus on Upgrade 2. It's a completely new detector, SciFi 2 . (Forget about cutting SciFi 1 modules shorter, reusing frames , etc.) Highly integrated with the “Mighty” silicon tracker.

vlora
Télécharger la présentation

SciFi 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. SciFi 2 B. Leverington, on behalf of the SciFi One group

  2. Points for today: • I will focus on Upgrade 2. • It's a completely new detector, SciFi 2. (Forget about cutting SciFi 1 modules shorter, reusing frames, etc.) • Highly integrated with the “Mighty” silicon tracker. • I will present a summary of our brainstorming discussion from last Wednesday. • Geometry and mechanics concept • Developments in Scintillating Fibres • SiPMs, Cooling, and Readout B. Leverington - SciFi 2 for LHCb Upgrade 2

  3. Radiation 1 MeV n eq. (no shielding) (50 fb-1) Ionising Radiation • Plots by Matthias Karacson for Upgrade 1 https://cds.cern.ch/record/2235317/files/LHCb-TALK-2016-380.pdf M0 M1 M2 M3 M4 M5 Shielding reduces 1MeV eq. fluenceby a factor of2.5 (T1) to 3.4 (T3) T1 3.3*1011neq/cm2 T3 4.2*1011neq/cm2 B. Leverington - SciFi 2 for LHCb Upgrade 2

  4. Slide from Lucia Grillo Occupancy correlated with ionizing dose… Maximum dose is about half in Upgrade 2 with current MT plan B. Leverington - SciFi 2 for LHCb Upgrade 2

  5. Ionising dose/Occupancy • Cut away the part of SciFi that sees too much dose and occupancy. • Build the Mighty tracker. • What defines the boundaries? • Not determined by the new 35 kGy line, but the average dose over the length • Losses due to ionising radiation equal to natural attenuation losses around 1000 Gy Plots by C. Joram B. Leverington - SciFi 2 for LHCb Upgrade 2

  6. The all-seeing tracker... B. Leverington - SciFi 2 for LHCb Upgrade 2

  7. We would like to avoid this. B. Leverington - SciFi 2 for LHCb Upgrade 2

  8. A hybrid module fibre silicon Services Services fibre B. Leverington - SciFi 2 for LHCb Upgrade 2

  9. A hybrid scint. fibre/silicon module • Remove the support structure of the silicon tracker from the material budget in the acceptance (use the existing SciFi module). Minimise the rest. • . • Proof of concept could be tested in Upgrade 1b for some beampipe modules • Interconnection of the silicon tracker box, Scifi sandwich and services will be challenging. • Needs a group with strong engineering and technical support to lead this part. Carbon Fibre 2 cm • Core cavities for cables, cooling pipes, data • Stiffness comes from the core not compressing or shearing and the skin not stretching or wrinkling 2 cm Scint.Fibre Carbon Fibre Bootstrap to the outside if access is required. B. Leverington - SciFi 2 for LHCb Upgrade 2

  10. Hit Efficiency and S/N • Reduced hit detection efficiency is the “aging” effect of the SciFi and is directly coupled to the S/N ratio. • For 50 fb-1 a reduction of efficiency of 1-2% is expected. Precise numbers are difficult to obtain before a few years of operation. • What are the knobs that we can turn? • Another photodetector? • Unlikely, given the geometry and properties of the fibre mats. B. Leverington - SciFi 2 for LHCb Upgrade 2

  11. Fibres - the NOL idea • Can we (LHCb) improve the fibre performance to start with a ‘better’ fibre in the beginning? • Energy loss dE/dx is given • Fibre construction, i.e. cladding, no suitable material with n < 1.42 • Activation and wavelength conversion  NOL idea NOL: Nanostructured Organo-silicon Luminophores Act Act WLS Act Act “Conventional” S.A. Ponomarenko et al., Nature Sci. Rep. 4 (2014) 6549 • Activator and WLS are chemically coupled using silicon links • Non radiative energy transfer (Förster mechanism) • Faster and more efficient than radiative emission See Lukas’ slides for more details. https://indico.cern.ch/event/808850/ B. Leverington - SciFi 2 for LHCb Upgrade 2

  12. NOL fibre Emission spectra (@ 15 cm from excitation point) • Peak wavelengths: • Blue NOL: 430 nm • Green NOL: 470 nm • Blue standard: 440 nm • Green standard: 530 nm Blue NOL fibre Green NOL fibre • 8 iterations of NOL fibres • Best were 50% faster than standard fibres, 1ns. • Best light yield about 15% lower than standard fibres. • Might be a material impurity problem. • No control over the production of the materials. • NOL WLS bars to be used for ALICE Diffractive detector upgrade • NOL11 fibres were considered for Mu3e. • Green fibres (emission peak 500 nm) might be still interesting to test. • No hadron irradiation done yet!!! X-ray results are ok. • Optimise for an irradiated detector Blue standard fibre Green standard fibre B. Leverington - SciFi 2 for LHCb Upgrade 2

  13. Other plastic scintillator developments Emmission spectra with QD https://doi.org/10.1016/j.jlumin.2013.09.051 • Most of the scintillators used in HEP were developed in the 60 and 70’s. • Is the marketbiased towards scintillators that match conventional PMTs? • Quantum Dot (QD) enhanced scintillators • nsdecay time, longer wavelengths possible • Still problems with attenuation length, non-trivial to dissolve in plastics • Testing new scintillating polymers (PEN, PET) • blue emission, no wavelength shifter yet • Slow decay times ( 10ns), good light yield • Red based dyes such as Nile Red as Wavelength shifter • <3ns decay time, dissolves easily in polymer • (Light) stimulated radiation damage recovery. The fluorescence spectra of PEN https://doi.org/10.1140/epjc/s10052-019-6810-8 The fluorescence lifetimes of Nile Red in polymers. https://doi.org/10.1016/j.cplett.2009.06.088 B. Leverington - SciFi 2 for LHCb Upgrade 2

  14. SiPM developments • For upgrade 2 (300 fb-1) : • 2.5*1012neq/cm2 • The SiPM characteristics ( gain, PDE, x-talk, After-Pulse) remain unchanged and the detector is still fully functional at this fluence. • Shielding in front of the calorimeter probably can’t be increased, but it’s not the only source of neutrons. • Development of radiation optimized SiPMs • Study optical focusing system on pixels with micro-lenses to reducing active surface and increase over-all PDE. • Study more radiation hard SiPM implementations (silicon structures) and the use of smaller pixels Shielding in Upgrade 1: Fluencereduction by a factor of2.5 (T1) to 3.4 (T3) Micro-lens simulation https://infoscience.epfl.ch/record/256964/files/EPFL_TH8842.pdf B. Leverington - SciFi 2 for LHCb Upgrade 2

  15. Cooling Dark Count Rate (unirradiated) • Need to go below -80C to achieve the same DCR with a factor 6 more neutron fluence • Going below -40C without vacuum “nearly impossible” • Reaching that Dew point is already difficult with dry gas • A vacuum based package for the 128 channel SiPM without dead regions on the edges is expected to be extremely challenging (impossible?). • A vacuum based cooling system with a clear fibre interface could be the solution. • A vacuum vessel with a clear fibre feedthrough and a 40cm long Kapton flex for thermalisation and feedthrough. • Cooling to -140°C (133K)is possible from the SiPM operation point of view. Upgrade 1 After-pulse probability Upgrade 1 B. Leverington - SciFi 2 for LHCb Upgrade 2

  16. Vacuum cooled + fibre guide solution 16 arrays in cryogenic box • Clear fibre guides • Wound with the same fibre pitch as mats for 1:1 matching • 10% light loss in preliminary tests • Length ~ 0.5 – 1 m • Separates the module from the SiPMs and cooling • No more dry “cold box”, just a light shielded connection • Light-injection for calibration moved out of the module 4 flexible clear-fibre lightguides Scintillating fibre mats B. Leverington - SciFi 2 for LHCb Upgrade 2

  17. Readout Electronics • Currently available FPGAs won’t work in the increased radiation environment. • Will require a clustering ASIC (+ raw mode for Light injection) • Probably smart to keep this separate from a refreshed PACIFIC • Most of SciFi 2 will be a “high-occupancy” region relative to the beampipe modules of Upgrade 1. • Many clusters, requires a different (SFV) data format • Time-of-arrival with the SciFi technology. • Application in LHCb unlikely (power consumption, too little direct light, mirror reflected light) B. Leverington - SciFi 2 for LHCb Upgrade 2

  18. Summary • SciFi-2 is a new detector. No chance to reuse SciFi-1. • Will integrate the silicon tracker with the SciFi-2 • This a very significant engineering effort. Start early with a strong team and leadership. • Standard scintillating fibres will work in Upgrade 2 • The increased loss due to higher average radiation damage would benefit greatly from fast, longer wavelength emission (green, red) • NOL fibres are faster, but lower light yield. Will check comparison after irradiation. • Still need experience from Upgrade 1 for better predictions. • Standard SiPMs will work in Upgrade 2 in a cryogenic bath down to 133K. • Some small benefits could be gained from extra shielding • Requires the development of clear fibre guides (10% light loss). • Gains from reduction of active silicon area B. Leverington - SciFi 2 for LHCb Upgrade 2

More Related