a scifi production center in nrc ki for lhcb upgrade › record › 2061526 › files ›...

A. Malinin1, A. Petrov1, V. Shevchenko1

For the LHCb collaboration

A SciFi production center in NRC KI for LHCb upgrade

Abstract: The Scintillating Fibre Tracker, SciFi for short, will be the main new tracking detector in LHCb. It will provide better than 100 µm spatial resolution, and

high rate capability and radiation hardness enabling a fast, 40 MHz, trigger rate with a capability to withstand 50 fb-1 integrated luminosity, delivered by LHC,

without a major performance degradation. The main active element of the tracker is a scintillating fibre ribbon with the SiPM readout. The ribbons consist of 6

layers of the 250 µm scintillating fibres Kuraray SCSF-78MJ, assembled by winding and bound together by the epoxy glue. NRC Kurchatov Institute, Moscow,

together with the colleagues from ITEP, CERN, TU of Dortmund and RWTH of Aachen are developing dedicated production centers with the aim to reach by 2016

production rate one ribbon per day per center, necessary to supply more than 1300 fibre ribbons (mats) needed for a new LHCb tracker.

SciFi detector concept and performance SciFi Tracker design and construction

[1] CERN-LHCC-2014-001 ; LHCB-TDR-015 , https://cds.cern.ch/record/1647400[2] P. von Doetinchem, H. Gast, Th. Kirn, G. Roper Yearwood, S. Schael,

Nucl.Instrum.Meth.A581:151-155, 2007, arXiv:astro-ph/0702567v1

[3] Th. Kirn et al., Production of Scintillating Fiber Modules for high resolution tracking

devices TIPP2014, Conference proceedings, Amsterdam, 5th June 2014[4] CERN-LHCb-PUB-2015-008, LHCB-EDR-M-M http://cds.cern.ch/record/2004811

The 3rd Annual Large Hadron Collider

Physics Conference

St. Petersburg, Russia

August 31st – September 5th , 2015.

SciFi modules series production and the quality assurance (QA)

winding, as well as many

other technological and

QA units which are being

developed together by the

groups of the SciFi project.

The production of the

SciFi fibre mats and

modules is organized at

This work is supported by Contract with Ministry of Education and

Science of Russia № 14.610.21.0002 and RFBR grant 14-02-03030. We

wish to thank CERN for their excellent beam facility and services.

Acknowledgements and References

Figure 1. The Outer Tracker position in the LHCb

experiment to be replaced by the SciFi Tracker.

Figure 10. The fibre QA scanner principal scheme. Figure 11. KI fibre quality scanner 3D-model. Figure 12. The fiber ribbon winding machine.

Figure 13. SciFi modules production flow-chart

developed for LHCb VELO

upgrade (with 10 µm track

resolution) and the SciFi

modules. themselves. The

result is shown in Fig.6. The

double Gaussian fit to the

residuals distribution for the

charge weighted cluster hits

gives σ1 = 59 μm σ2 = 203

μm with 79 µm weighted

average effective sigma.

.

Module Centre

Fibre Quality Centre (CERN)

10,000 km scintillating fibre

Fibre Winding Centre

Fibre Winding Centre

Fibre Winding Centre

Fibre Winding Centre

Aachen Dortmund Lausanne Moscow

Tested fibre

Module Centre

Heidelberg

Amsterdam

1300 tested fibre mats

144 tested modules

CERN

Half-panel: Honeycomb (Nomex) + CFRP skin

Mirror side

Readout side

Figure 6. SciFi module spatial resolution

with one side mirror (beam track residuals)

Figure 9. 128-ch SiPM to readout SciFi signals

Figure 7. Modular design: 1 of 3 SciFi stations

Figure 8. SciFi module consists of 8 fibre mats

1NRC Kurchatov Institute, akademika Kurchatova sq.,1

Moscow, 123182, Russia

Shevchenko_VI@nrcki.ru

Figure 3. The SciFi detector fabrication conceptFigure 2. The radiation environment of the LHCb tracker area, which

corresponds to the integrated dose of 50 fb-1 : a) The total dose, and b) the

1 MeV equivalent neutron fluence per cm2 .

Figure 5. The Kuraray SCSF-78MJ scintillating fibre

irradiation tests summary: The ratio of the irradiated fibre

attenuation length Λirr to initial attenuation length Λ0, as a

function of the integrated dose in kGy.

Increased luminosity of the LHC requires a substantial upgrade of

the LHCb experiment [1]. One of the first detectors to be

completely replaced is the LHCb Outer Tracker (Fig.1). A much

higher radiation dose and neutron fluence, which correspond to

50fb-1 (Fig.2a,b) require a new tracker concept. The concept of the

scintillating fibre tracking detector is not new, but the SciFi highest

resolution and largest area detector with the direct multichannel

SiPM readout, providing better than 100 µm spatial resolution over

several square meters area, comes from the PEBS experiment

tracker proposal [2] by RWTH group. They, together with other

LHCb members of the SciFi

project, developed the winding

technique, using a precise,

threaded with 275 µm pitch,

rotating drum a winding wheel,

(Fig.3,4) to produce a 6 layer,

2500 mm long and 132 mm wide

Figure 6 shows a new

modular layout of the SciFi

tracker’s one out of three

(Fig.1) tracking stations.

Each station consist of four

layers of SciFi modules

mounted on C-frames with

two vertical (X) and two

stereo (U,V), at ± 5º to the

vertical, fiber orientations.

The modules (Fig.7) have

the same design except for

two innermost in each layer,

and consist of 8 mats

readout from one side by

four 128-channel SiPMs

(Fig.8), directly connected to

the end of the mat. Other

ends of the fiber mats are

equipped with mirrors. The

structure is closed by two

half-panels which are made

from a honeycomb core and

single carbon skin by gluing.

A readout box with front-end

electronics is attached to the

top and bottom of each

module. It has an insulated

cold compartment to keep

the SiPMs at -40°C working

temperature during the run.

Figure 14. Production clean zone of 240 m2

ISO7-ISO8 class is being constructed at NRC KI

Figure 15. NRC KI production clean room layout

The series production of the SciFi mats requires a clean room and a

set of equipment (Fig.10-12) for fibre quality assurance, and mat’s

seven centers (Fig.13) four of which are set up to produce over 1300

mats. The center at NRC Kurchatov Institute is shown in Fig.14,15.

The clean zone (Fig.15) is divided in four compartments, for entrance,

the QA fibre scanner (Fig.11), winding machine (Fig.12), and

assembly. The fibre QA scanner measures the fibre diameter, with high

frequency and 1 μm accuracy, it monitors the attenuation length and

light yield, and detects eventual structural defects such as the bumps,

necks and cracks. Its principal scheme is shown in Fig.10. The main

part of the production is winding. The mixture of Epotec 301-2 epoxy

glue and the TiO2 powder (20% by weight) is prepared in the winding

compartment and applied 6 times after each fibre layer is completed.

The curing process takes 48 hours and 3 precision wheels (Fig.4) are

needed to make 1 mat per day to ensure the required production rate

per shift. At NRC KI center, work in 2 shifts is foreseen.

mats out of 250 µm diameter scintillating optical

fibre [3], packaged in a dense, hexagonal structure

and bounded together by epoxy glue. The fibre was

carefully chosen after many tests. It is SCSF-78MJ,

produced by Kuraray company in Japan. Its

radiation hardness (Fig.5) was measured with

different linear energy transfer beams and dose

rates. The data demonstrates less than 20% of

expected transparency loss for the highest dose

near the LHCb beam pipe, covering only a few tens

of cm in Y direction (fibre direction in the mats).

a) b)

The SciFi spatial resolution was measured in the test beam at SPS

[4]. The beam tracks were reconstructed using the Si-pixel tracker

Figure 4. The NRC KI precision winding wheel

Shape accuracy: 70 µmOuter Ø = 817 mm