Ⅱ-9. Instrumentation

RIKEN Accel. Prog. Rep. 53

Intermediate Tracker Integration in sPHENIX
D. Cacace,∗2 Y. Akiba,∗1 K. Cheng,∗3 E. Desmond,∗2 T. Hachiya,∗1,∗4 T. Kondo,∗5 C. Kuo,∗3 M. Lenz,∗2E. Mannel,∗2 C. Miraval,∗2 M. Morita,∗4 I. Nakagawa,∗1 R. Nouicer,∗2 R. Pisani,∗2 M. Shibata,∗4 C. Shih,∗3A. Suzuki,∗4 T. Todoroki,∗1 X. Wei,∗6 and R. Xiao∗6The sPHENIX collaboration at RHIC is constructing a major upgrade to the PHENIX detector, consisting of an entirely new spectrometer based on theformer BaBar solenoid magnet and the PHENIX facilities and infrastructure.1) The upgrade will allow for
an in depth jet and beauty quarkonia physics program
to address the fundamentals of strongly coupled quarkgluon plasma. The solenoid magnet is sandwiched byhadronic calorimeters (HCal) followed by an electromagnetic calorimeter (EMCal). Inward of the EMCal
is a time projection chamber (TPC), INTermediate silicon strip Tracker (INTT) and MAPS-based VerTeX
detector (MVTX) composing the sPHENIX trackingsystem. All of the subsystems have their challenges
when coalescing with one another, but the INTT is ofparticular interest in terms of integration considerations.
The INTT design, constrained by its neighbors, hasbeen heavily influenced by the other sPHENIX tracking components. The MVTX’s active region has anouter diameter of 10.5 cm and has a service cone longitudinally starting at 25 cm from the vertex and grows
to a diameter of 21.5 cm. The TPC has an inner diameter of 40 cm that spans a length of 117 cm from thevertex in both directions. The INTT has to fit between
these envelopes. The INTT detector itself consists ofthree main components each consisting of several subcomponents as seen in Fig. 1.
The first main component is the active region containing the silicon sensors. Four sensors are wire
bonded to 52 FPHX chips1) which are wire bonded
and epoxied to two high-density interconnects (HDI)
and both are epoxied to a stave for structural support.
This assembly, known as a ladder, as seen in Fig. 2,
covers an acceptance of pseudorapidity of ±1.1. Several ladders arranged tangentially to a circle aroundthe vertex compose what is referred to as a barrel.
The active area of the sensors is approximately half
the width of the HDI, which lends itself to a configuration where two barrels are required to obtain hermetic
2π azimuthal coverage, referred to as one layer. The
detector consists of four barrels or two layers at approximate radial positions of 7.2, 7.7, 9.7 and 10.3 cm
from the beam axis. The layers are held in position
∗1

∗2
∗3
∗4
∗5
∗6

RIKEN Nishina Center
Brookhaven National Laboratory
National Central University
Nara Women’s University
Tokyo Metropolitan Industrial Technology Research InstitutePurdue University- 118 -Fig. 1. INTT in sPHENIX 3D model cross section.

Fig. 2. INTT ladder 3D model.

with a series of stave end-caps and end-rings.
The end-rings also attach the barrels to the second
main component, the service barrel. The service barrel, consisting of two carbon fiber tubes and miscellaneous brackets, carries the services (cables, cooling,nitrogen, etc.) from the ladders to beyond the TPC
volume. The cables terminate just beyond the TPCand connect to the readout cards (ROC). The coolingand nitrogen connect to manifolds beyond the TPC.
From there all the services are routed to the respective
racks and/or infrastructure facilities. The outside of
the service barrel also has features that allow for thedetector and service barrel to installed as a singularunit.
Lastly, the third main component of the INTT is its
support structure. Consisting of a carbon fiber tube
and aluminum I-beams, the support structure facilitates the installation and operation of the INTT andall of its services. The I-beams connect the carbon fiber
tube to the inner HCal creating a direct load path forthe detector and direct service routing to the INTT’sracks. The I-beams also support the ROCs at an appropriate location for the HDI extension cables thathave a maximum length of 120 cm.
Prototype ladders are being produced to verify thedesign and assembly fixtures for production.2) Prototype end-rings will be produced in conjunction with theladders to verifying the barrel configurations. The service barrel and support structure designs are far along
and are continuously being verified that they properly
integrate with the surrounding sPHENIX detectors.
References1) sPHENIX Conceptual Design Report (2018), https://indico.bnl.gov/event/4625/attachments/18432/23516/
sphenix-conceptual-design_051918.pdf .
2) C. Miraval et al., in this report.