R3B Heavy Ion Tracking

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R3B Heavy Ion Tracking
Roman Gernhäuser, TU-München
Status of the High Rate Diamond Detectors for
Heavy Ion Tracking and TOF

• detector concept
• larger area prototypes
• test experiment
• electronics development

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R3B (Reactions with Relativistic Radioactive
Beams) Setup
Dp/p 10-4 _at_ 2.5 accept.
Measurement of all kinematic variables in a HI
reaction Different tasks High resolution
tracking in the super FRS, radiation hard
(SFRS) 106 cm-1 s-1 2 x TOF (SFRS target)
(reaction products) low material budget
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R3B Detector Concept

• tracking layer
• 50 x 50 mm, d 100 mm, PC-CVDD
• 140 mm pitch (125mm strips, 15 mm gap)
• only digital position information
• multiplexed readout in vacuum

• timing layer
• 50 x 50 mm, d 100 mm, PC-CVDD
• 16 rate matched strips, y information, trigger
• analog preamplification in vacuum
• discriminator _at_ 5 m distance

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Status 2007

• detailed investigations
• using 40 x 1cm2 sample detectors
• material properties checked
• radiation hardness proven
• segmentation scheme optimized
• lithography improved (15mm)
• efficiency gt 98
• fast preamps vacuum suited
• good TOF resolution
• 1st prototype of APV readout

next steps intermediate size prototypes separate
detector electronics test of high resolution
tracking
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Larger Area Detector
4 prototypes produced 2 operational lithography
under control Frontside 128 strips 170 mm wide
20 mm gap Backside 16 strips
25.4 mm
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Full system test in R3B Setup

• APV25 chip
• 128 channels
• preamplifier, shaper on board
• 8 MIPS dynamic range
• vacuum suitable
• ADCs on GTB bridge board

• 25.4 x 25.4 mm2
• 128 micro strips (200 µm )

M.Boehmer, TU Muenchen, PhD Thesis (2006)
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trigger scintillator
100 µm
100 µm
diamond
intrinsic resolution 200 µm
600 AMeV 124Xe
position dia1 0.2mm
S. Schwertel et al., GSI Scientific Report 2007
(GSI Report 2008-1) 216
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Persistent Particle Induced Currents
many samples were investigated 70 show
particle induced current variation with time and
producer same production parametersbut
different behaviour about 50 yield investigation
of properties not yet finished
as grown
3 inch waver
polished
beam off
schematically
current
t s
1
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Improved Samples

• two step growth and
• polishing process to reduce stress
• round shaped corners
• metallization by sputtering
• Additional heat treatment
• (We saw much better performance
• on single crystal material)

_
cut
Less stress larger grains

_


Si substrate

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TOF measurement
small detector
large detector
C 50pF APV impedance matching?
C 5pF 50W impedance on both sides
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1ns Shaping
larger impedance less noise sensitive better
adopted to APV simple signal transport use of
standard discriminators
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Improved Electronics
Impedance matching and Shaping
Amplifier Discriminator TOT measurement
Capacitive charge splitter
APV
VME
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Task List

• Detector Production
• New material with less persistent photo current
  (PPC) after irradiation
• New metallization and heat treatment.
• Full size detectors

• Signal Properties
• New shaping preamplifiers
• Signal splitting to fit APV range
• New discriminators

• Test experiments
• 48MeV Li beam in Munich (two detectors) (Nov
  2008)
• 1GeV beam GSI (four detectors in a row) (2009?)