PROPOSAL

for a Forward Silicon Vertex Tracker (FVTX)

for the PHENIX Experiment

**Proposal for a Forward Silicon Vertex Tracker (FVTX) for the PHENIX
Experiment**

*draft author list - not complete, not confirmed*

M. Baker, R. Nouicer, R. Pak, A. Sukhanov, P. Steinberg

Brookhaven National Laboratory, Chemistry Department, Upton, NY
11973-5000, USA

Z. Li

Brookhaven National Laboratory, Instrumentation Division, Upton, NY
11973-5000, USA

J.S. Haggerty, J.T. Mitchell, C.L. Woody

Brookhaven National Laboratory, Physics Department, Upton, NY
11973-5000, USA

O. Drapier, A. Debrain, F. Gastaldi, M. Gonin, R. Cassagnac de Granier,
F. Flueret, A. Karar

LLR, Ecole Polytechnique, Palaiseau, France

A.D. Frawley

Florida State University, Tallahassee, FL 32306, USA

J. Crandall, J.C. Hill, J.G. Lajoie, C.A. Ogilvie, A. Lebedev, H. Pei,
J. Rak, G.Skank,

S. Skutnik, G. Sleege, G. Tuttle

Iowa State University, Ames, IA 56011, USA

B. Hong

Korea University, Seoul, Korea

N. Saito, M. Togawa, M. Wagner

Kyoto University, Kyoto 606, Japan

J.G. Boissevain, M.L. Brooks, S. Butsyk, H.W. van Hecke, J. Kapustinsky,
G.J. Kunde, D.M. Lee, M.J. Leitch, M.X. Liu, P.L. McGaughey, A.K.
Purwar, W.E. Sondheim

Los Alamos National Laboratory, Los Alamos, NM 87545, USA

G. Kyle, S. Pate, X.R. Wang

New Mexico State University, Las Cruces, NM, USA

B. Bassalleck, D.E. Fields, M. Malik

University of New Mexico, Albuquerque, NM, USA

J. Gosset, H. Periera

CEA Saclay, Gif-sur-Yvette, France

J.H. Kang, D.J. Kim

Yonsei University, Seoul, Korea

[1 Executive Summary 1](#executive-summary)

[2 Physics Goals of the FVTX Endcap Upgrade
5](#physics-goals-of-the-fvtx-endcap-upgrade)

[2.1 Heavy-ion collisions and the Quark Gluon Plasma
5](#heavy-ion-collisions-and-the-quark-gluon-plasma)

[2.1.1 Energy Loss and Flow of Heavy Quarks
5](#__RefHeading___Toc119116790)

[2.1.2 Open charm and Beauty Enhancement
9](#open-charm-and-beauty-enhancement)

[2.1.3 J/ Suppression and Comparisons with Open charm, ' and
11](#j-suppression-and-comparisons-with-open-charm-and)

[2.1.4 Drell-Yan 12](#__RefHeading___Toc119116793)

[2.1.5 Improvement in the Reaction Plane Resolution
12](#improvement-in-the-reaction-plane-resolution)

[2.2 Proton(Deuteron)+Nucleus Collisions and Nuclear effects on Gluons
in Nuclei
12](#protondeuteronnucleus-collisions-and-nuclear-effects-on-gluons-in-nuclei)

[2.2.1 Gluon saturation via Heavy-quarks
13](#gluon-saturation-via-heavy-quarks)

[2.2.2 Baseline for Nucleus-Nucleus 21](#baseline-for-nucleus-nucleus)

[2.2.3 Disentangling the physics of J/ψ
21](#disentangling-the-physics-of-jψ)

[2.3 Polarized Proton Collisions and the Gluon Spin Structure of the
Nucleon
21](#polarized-proton-collisions-and-the-gluon-spin-structure-of-the-nucleon)

[3 Simulations and Required Performance for the Si Endcap Upgrade
23](#simulations-and-required-performance-for-the-si-endcap-upgrade)

[3.1 Open Charm Measurement 23](#open-charm-measurement)

[3.2 Open Beauty Measurement 25](#open-beauty-measurement)

[3.3 Trigger Plans 27](#trigger-plans)

[3.4 Si Endcap Event Rates 27](#si-endcap-event-rates)

[3.5 Matching to Muon Spectrometers 28](#matching-to-muon-spectrometers)

[3.6 Integration with PHENIX 28](#integration-with-phenix)

[4 FVTX Detector system 28](#fvtx-detector-system)

[4.1 Overview 28](#overview)

[4.2 Silicon readout chip - PHX 30](#silicon-readout-chip---phx)

[4.3 Silicon Mini-strip Sensors 32](#silicon-mini-strip-sensors)

[4.4 Electronics Transition Module 35](#electronics-transition-module)

[4.5 Mechanical Structure and Cooling
36](#mechanical-structure-and-cooling)

[4.5.1 Endcap Ladder Structure 38](#endcap-ladder-structure)

[4.5.2 Radiation Length 40](#radiation-length)

[Endcap Analysis Summary 40](#endcap-analysis-summary)

[4.6 40](#section-7)

[5 R+D Schedule, Responsibilities and Budget
40](#rd-schedule-responsibilities-and-budget)

[5.1 Schedule 40](#schedule)

[5.1.1 Responsibilities 41](#__RefHeading___Toc119116821)

**List of Figures**

[Figure 1 - Conceptial layout of the PHENIX FVTX showing the four
lampshade silicon planes at each endcap.
3](#__RefHeading___Toc119116920)

[Figure 2 - Suppression of high-p~T~ hadrons and pions as seen in Au+Au
vs d+Au. 6](#__RefHeading___Toc119116921)

[Figure 3 - Large elliptic flow for light hadrons in Au+Au collisions is
near the hydro limit . 6](#__RefHeading___Toc119116922)

[Figure 4 - In PHENIX preliminary results shown at QM05, even charm
seems to suffer energy loss at mid-rapidity.
7](#__RefHeading___Toc119116923)

[Figure 5 - Preliminary results for charm from single electrons in
PHENIX and STAR shows flow for small p~T~ and somewhat inconsistent for
larger p~T~. 7](#__RefHeading___Toc119116924)

[Figure 6 - Single electron data of PHENIX compared with two extreme
models of charm p~T~ distribution. From ref. 5.
8](#__RefHeading___Toc119116925)

[Figure 7 Charm enhancement expected at RHIC energy from ref. 8. In both
panels, contribution from the initial gluon fusion (solid), pre-thermal
production (dot-dashed), and thermal production (dashed, lowest) are
shown. The left panel is the calculation with energy density of 3.2
GeV/fm^3^, while the right panel shows the case with energy density 4
times higher. 10](#__RefHeading___Toc119116926)

[Figure 8 - Rapidity distribrution from Vogt for charm in pp collisions
at s = 200 GeV. Roughly half the total cross section comes from the
region of the FVTX coverage, \|y\|\>1.2
11](#__RefHeading___Toc119116927)

[Figure 9. Mass spectra for the J/ and \', showing the substantial
improvement in separation expected with a vertex detector (yellow, 100
MeV resolution) compared to that without a vertex detector (black, 150
MeV resolution). The number of J/ and ' in this plot represents our
expectation for a \~25 pb^-1^ p+p run. 12](#__RefHeading___Toc119116928)

[Figure 10 - Gluon shadowing from Eskola as a function of x for
different Q2 values: 2.25 GeV^2^ (solid), 5.39 GeV^2^ (dotted), 14.7
GeV^2^ (dashed), 39.9 GeV^2^ (dotted-dashed), 108 GeV^2^ (double-dashed)
and 10000 GeV^2^ (dashed). The regions between the vertical dashed lines
show the dominant values of *x~2~* probed by muon pair production from
*dd*bar at SPS, RHIC and LHC energies. 13](#__RefHeading___Toc119116929)

[Figure 11 - J/ψ nuclear dependence versus rapidity compared to
theoretical predictions with several types of gluon shadowing^15^.
14](#__RefHeading___Toc119116930)

[Figure 12 Alpha versus x~2~ and x~F~ from measurements at three
different energies shows that the suppression does not scale with x~2~
but does exhibit approximate scaling with x~F~. Alpha is defined as
$\sigma_{A} = \sigma_{p}A^{\alpha}$, where $\sigma_{p}$($\sigma_{A}$) is
the nucleon (heavy nucleus, A) cross section. Data is from PHENIX (s =
200 GeV/c)^15^, E866/NuSea (s = 39 GeV/c) and NA3 (s = 19 GeV/c).
15](#__RefHeading___Toc119116931)

[Figure 13 - Single muon p~T~ distributions for charm, beauty and
backgrounds from low-mass meson decays.
17](#__RefHeading___Toc119116932)

[Figure 14 - Single muon p~T~ distribution for charm compared to
backgrounds with a vertex cut showing signal/noise well above one even
at p~T~=0.5 GeV/c. 17](#__RefHeading___Toc119116933)

[Figure 15 - Single electron pT spectrum without a vertex detector.
18](#__RefHeading___Toc119116934)

[Figure 16 -- Distance of closest approach (DCA) distribution for
heavy-quark and backgrounds showing how backgrounds can be greatly
reduced by a vertex detector which allows cuts on the DCA.
18](#__RefHeading___Toc119116935)

[Figure 17 - Gluon shadowing predictions along with PHENIX coverage. The
red bars indicate the additional range provided by the vertex upgrade,
while the blue bars cover the PHENIX baseline. The three theoretical
predictions are for different Q transferred, blue, green and red lines
are *Q* = 10, 5 and 2 GeV/c respectively, from Frankfurt and Strikman.
18](#__RefHeading___Toc119116936)

[Figure 18 - Dimuon mass spectrum from E866/NuSea showing the mass
region used in their analysis which excludes masses below 4 GeV. Lower
masses were excluded because of the large backgrounds from open charm in
that region. 19](#__RefHeading___Toc119116937)

[Figure 19. Gluon shadowing predictions along with PHENIX coverage. The
red bars indicate the additional range provided by the Endcap vertex
upgrade, green bars are for the barrel upgrade, while the blue bars
cover the PHENIX baseline. The red and blue curves are theoretical
predictions of shadowing from EKS and FKS for different Q values.
21](#__RefHeading___Toc119116938)

[Figure 20. Expected x-range for different channels used to extract the
gluon spin structure function. The blue bars indicate PHENIX's existing
capability, green bars are for the Barrel upgrade, while the red bars
indicate the additional coverage provided by the p roposed Endcap vertex
upgrade. The curves show various estimates of the expected gluon
polarization. 22](#__RefHeading___Toc119116939)

[Figure 21. Single muon p~T~ distributions for charm, beauty and
backgrounds from low-mass meson decays, as expected for the 2003 d+Au
run. Note that the light-meson decays are above charm up to near 4
GeV/c. The black curve is for pion and kaon decays, green is charm and
red is beauty. 24](#__RefHeading___Toc119116940)

[Figure 22. The p~T~ distribution of muons that decay within 1 cm of the
collision vertex. The red histogram is for charm decays while the black
is for pion and kaon decays. 25](#__RefHeading___Toc119116941)

[Figure 23. The reconstructed Z-vertex distribution for J/ from B decays
(black line) and for prompt J/ (red line). Note that the J/ yield has
been scaled down by a factor of 100. The relative yield of J/ from B
decays versus prompt J/is estimated to be about 1%.
26](#__RefHeading___Toc119116942)

[Figure 24 - 3-D model of the full vertex detector showing the barrel
portion and the endcaps on left and the endcap on the right. Also shown
is the VTX mounting fixture. 29](#__RefHeading___Toc119116943)

[Figure 25 - The FNAL FPIX2 pixel readout chip
30](#__RefHeading___Toc119116944)

[Figure 26 - Conceptual layout of the PHX pixel readout chip. The left
side graphic depicts the general layout of the chip. Green is the area
for bonding, blue the programming interface, red the discriminator,
orange the pipeline and yellow the digital interface. The right side
graphic shows the bonding layout, the spacing is 200 micron. The signal
and power bus will be routed on the surface on the chip and bonded via
the bump bonds on the ends of the chip.
31](#__RefHeading___Toc119116945)

[Figure 27 - The equivalent noise charge (ENC) verus capacitance.
32](#__RefHeading___Toc119116946)

[Figure 28 - Three silicon detectors will be used. The largest will have
6 chips reading out 3072 strips, the intermediate silicon will have 5
chips reading out 2560 strips and the smallest silicon is half the size
of the largest with 3 chips reading out 1536 stri ps. (All dimensions
are in millimeter) 33](#__RefHeading___Toc119116947)

[Figure 29 - A sector assembly will have 24 carbon panels (one shown
here in brown) in azimuth, each of them carrying 4 silicon detectors
(blue), two in the front and two in the back. They overlap on the edges
by a few millimeters to avoid dead areas. The bus on a silicon assembly
is routed on the chips as described earlier, the connection of the inner
silicon detectors is realized via a kapton bus (golden).
33](#__RefHeading___Toc119116948)

[Figure 30. Each station carries 96 silicon detectors. The stations are
placed at \~20, 26, 32 and 38 cm from the interaction point.
34](#__RefHeading___Toc119116949)

[Figure 31. Each endcap will have 4 stations of silicon detectors. The
inner station has a reduced size in order to not interfere with the HBD
acceptance. 34](#__RefHeading___Toc119116950)

[Figure 32 - The transition module concept
35](#__RefHeading___Toc119116951)

[Figure 33 - An isometric view of the VTX showing all of the internal
features coaxial with the beam tube, namely (moving out from the beam
tube), two cylinders of pixel detectors, two cylinders of strip
detectors, the GRFP structure (gray in color), and finally, the
cylindrical enclosure wall. 38](#__RefHeading___Toc119116952)

[Figure 34 - 3D model of octagonal disk like structures for the endcap
ministrips. Cooling tubes are to demonstrate both the number and
routing. 39](#__RefHeading___Toc119116953)

[Figure 35 - The octagon panel structure is on the right with the
cooling channel shown. A heat load of 0.1 W/cm\*\*2 is assumed.
39](#__RefHeading___Toc119116954)

[Figure 36. Illustration of an embedded cooling passage arrangement in
the composite sandwich used in the endcap thermal and static
calculations. The upper panel depicts a circular tube with supports and
the bottom panel shows a flattened tube which enhances heat transfer and
provides a thinner sandwich. 39](#__RefHeading___Toc119116955)

[Figure 37. Estimated normal radiation length for the endcap octant
panel for different tube diameters. 40](#__RefHeading___Toc119116956)

[Figure 38 - PHENIX Forward Silicon Vertex (FTV) project timeline.
41](#__RefHeading___Toc119116957)

**List of Tables**

[Table 1 -- Rates for RHIC p+p. 27](#__RefHeading___Toc119116958)

[Table 2 - Summary of the parameters of the FVTX disks.
29](#__RefHeading___Toc119116959)

[Table 3 Buffer requirements for the transition module for AuAu events,
various options of readout lines/chip, different levels of chip ganging,
and a very conservative noise estimate. Also, the time to readout an
event is given for the same conditions.
36](#__RefHeading___Toc119116960)

# Executive Summary

We propose the construction of two Forward Silicon Vertex Trackers
(FVTX) for the PHENIX experiment at RHIC. These would extend the vertex
capability of the PHENIX Silicon Vertex Tracker (VTX) to forward and
backward rapidities with secondary vertex capability in front of the
PHENIX muon arms.

The FVTX will allow robust identification of heavy-quark (charm and
beauty) production via displaced vertices in the forward and backward
rapidity regions in *A+A*, *p(d)+A*, and polarized *p+p* collisions. In
addition, it will allow one to largely eliminate backgrounds from pion
and kaon decays and pion and kaon punch-throughs, which currently limit
most dimuon and single muon measurements. It provides new coverage in
the small-x region where gluon saturation is thought to be important and
greatly extends the range over which PHENIX can examine the gluon
structure functions and their polarization.

The most important physics drivers for this upgrade can be summarized in
three broad classes, associated with the type of collision:

-   A+A collisions and the Quark Gluon Plasma:

    -   Study of energy loss and flow of heavy quarks into very forward
        and backward rapidity regions using robust charm and beauty
        measurements over a much broader range than available with the
        barrel VTX detector alone and with much greater precision than
        is possible with the muon detectors alone. This allows study of
        the geometrical and dynamical effects into the forward and
        backward rapidity regions of the hot-dense matter created in
        high-energy heavy-ion collisions

    -   A more precise open charm measurement will provide a solid
        \"denominator\" for comparison with production of bound states
        of heavy quarks (J/ψ and ). These comparisons will allow
        isolation of common physics (e.g. initial-state effects such as
        those on the gluon structure function) and physics that only
        affects the bound states (e.g. final-state absorption); and will
        provide strong constraints on recombination production of the
        J/ψ by determining a precise open-charm cross section over a
        broad rapidity range.

    -   Allow direct measurement of s at mid-rapidity by eliminating the
        large random backgrounds from light-meson decays. Also will
        improve the mass resolution and signal/noise for J/ψ production.

    -   Allow unambiguous measurement of the Drell-Yan continuum,
        heavy-flavor dimuon continuum, and possibly phi vector meson
        measurements, also because of elimination of the backgrounds
        from light mesons.

    -   Provide a more accurate reaction plane for studies of many other
        signals given the much larger rapidity coverage provided by the
        FVTX extension.

-   p(d)+A collisions and small-x or gluon saturation physics:

    -   Allow study of the gluon structure function modification in
        nuclei at small *x* values where gluon saturation or shadowing
        is thought to be important

    -   Determine the initial state for AA collisions and provide a
        robust baseline for cold-nuclear matter effects in studies
        hot-dense matter in heavy-ion collisions

    -   Help untangle the complicated physics of J/ψ and production by
        providing robust measurements of open-heavy quark production
        that can, by contrast, separate initial and final-state physics
        for the resonances.

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-   Polarized p+p collisions, and the contribution of the gluon to the
    spin of the nucleon:

    -   Provide a much larger x range (from x = 10^-2^ down to 10^-3^)
        over which the mostly unknown gluon polarization (*∆G/G*) can be
        determined. Without the FVTX the range covered is likely to not
        be sufficient to study the shape of any polarization or to
        determine its peak value

With the present PHENIX detector, heavy-quark production in the forward
and backward directions has been measured indirectly through the
observation of single muons. These measurements are inherently limited
in accuracy by systematic uncertainties resulting from the large
contributions to the single muon spectra from prompt pion and kaon
semi-leptonic decays and from pion and kaons which punch through the
entire muon system and are mistakenly tagged as muons. In addition, the
statistical nature of the analysis does not allow for a
model-independent separation of the charm and beauty contributions. The
FVTX detector will provide vertex tracking with a resolution of \<200 m
over a large coverage in rapidity (1.2 \< \|\| \< 2.2) with full
azimuthal coverage. This will allow for vertex cuts which separate
prompt particles, decay particles from short-lived heavy quark mesons,
and decay particles from long-lived light mesons (pions and kaons). In
addition, beauty measurements can be made directly from BJ/X by looking
for a displaced J/ vertex, which will allow charm and beauty
contributions to be separated in semi-inclusive single lepton
measurements. Therfore, with this device significantly enhanced and
qualitatively new data can be obtained. A more robust and accurate
measurement of heavy-quark production over a wide kinematic range will
be possible. This new reach to forward and backward rapidities
complements that already planned from the central barrel vertex (VTX)
silicon detector, which will cover \|\| \< 1.2.

-   
-   
-   
-   
-   

The FVTX would be composed of four silicon mini-strip planes in each
endcap covering angles between 10 and 35 degrees, matched to the muon
arms. Each silicon plane is composed of wedges of mini-strips with 50 μm
pitch in the radial direction and lengths in the phi direction varying
from 1.9 mm at small theta to 13.5 mm at 35 degrees. A resolution in
z~vertex~ of 200 μm can be achieved with a maximum occupancy in central
Au-Au collisions of less than 1.5%.

![](media/image4.png){width="5.383333333333334in" height="3.55in"}

[]{#__RefHeading___Toc119116920 .anchor}Figure 1 - Conceptial layout of
the PHENIX FVTX showing the four lampshade silicon planes at each
endcap.

The FVTX will have about 2 million electronics channels which will be
read out with a Fermilab PHX chip which bump-bonds directly to the
mini-strips. This chip will provide analog and digital processing with
zero-suppression and produces a digital output which is \"pushed\" out
at 140-840 Mbps to an intelligent readout board containing FPGAs where
the data can be prepared in a standard PHENIX format and, in parallel, a
fast \"level-1\" trigger algorithm can be run to enable triggering on
interesting heavy-quark events.

The PHX chip is a slightly modified version of recent Fermilab front end
silicon chips developed for BTEV. It will take about one year for the
layout modifications that enable these new chips to match our wedge
mini-strip geometry to be completed and tested. And more...

A collaboration of xx institutions with approximately yy physicists and
engineers has formed to carry out this project. The collaboration brings
expertise in silicon vertex detectors from FNAL E866, SSC, L3 and PHOBOS
and general experience on construction and operation of large detector
subsystems from the PHENIX muon arms and xxx. Members of the
collaboration come with extensive experience in heavy-quark and J/
physics, small-x nuclear effects, gluon structure functions and
polarization and various physics with muons, and expertise in
simulations and analysis to support these.

With the help of an LDRD Exploratory Research (ER) project from LANL
during FY02-FY04 we were able to advance the proposed project to a full
conceptual design and to settle many of the R&D issues necessary to
advance a full proposal. We are confident that the remaining issues can
be solved within the next year and that the full detector construction
could be started by beginning of FY07.

We anticipate that the full project will be funded by the DOE Office of
Nuclear Physics at a total cost of \$4.5M. As a first step in parallel
and in preparation for construction of the full project, a prototype
endcap vertex detector covering approximately ¼ of one endcap will be
funded by a new LANL LDRD grant of \$1.25M/yr. This will be built during
FY06-FY08 and operated for an initial physics measurement by the end of
that period. Construction of the full detector should proceed on a time
scale that will allow installation of the final/full detector starting
in late FY08. The full installation would be complete by the end of
FY09.

A preliminary management plan of the VTX detector project, which also
discusses the role and expected responsibilities of the participating
institutions, is included in this document.

The proposal has the following structure. The physics motivation for the
upgrade and the proposed measurements are documented in section 2. The
feasibility of these measurements and the required detector performance
are discussed in section 3. Section 4 gives a detailed description of
the vertex tracker and the technical aspects of the proposed project.
Section 5 discusses our R&D plan. A draft of our management plan,
section 6, specifies deliverables and institutional responsibilities.
Section 7 lays out the budget request and the proposed schedule.

# Physics Goals of the FVTX Endcap Upgrade

The PHENIX Forward Vertex Detector (FVTX) endcaps complement the barrel
vertex detector (VTX) already being built for PHENIX by providing much
larger coverage in rapidity (two additional units of rapidity compared
to about one), extending the sensitivity to gluon momentum fraction (x)
down to x\~10^-3^ , and providing a broad reach in transverse momentum.
Heavy-quark mesons and bound states of heavy-quarks (quarkonia) coming
from heavy quark meson decay can be identified by their short detached
vertices, and the light-meson yields that ordinarily comprise most of
the backgrounds to these measurements can be largely eliminated
according to their large detached vertices. Prompt muons and kaons which
punch through the muon system can be eliminated by their lack of a
displaced vertex.

We will now discuss the main physics goals by starting with those that
are important in heavy-ion collisions, then those of interest in proton
or deuteron nuclear collisions, and finally those that related to
polarized proton collisions.

## Heavy-ion collisions and the Quark Gluon Plasma

The main goal of the RHIC program is the identification and study of the
hot high-density matter created in heavy-ion collisions, i.e. the Quark
Gluon Plasma (QGP). The energy loss in this dense matter as seen by the
suppression in the yields at high transverse momentum for light quarks,
the large flow seen at small momenta indicative of early thermalization,
and other signatures observed by the RHIC experiments point to large
densities created in these collisions. But the composition of this
high-density matter, whether or not it is deconfined, and what the
degrees of freedom are, remain beyond the reach of present measurements.
The FVTX detector coupled with the muon detector systems will allow for
precision measurements of open charm and beauty versus rapidity, p~T~
and reaction plane, much improved measurements of vector mesons (J/, ',
) as well as an unambiguous measurement of dimuons from Drell-Yan in
heavy-ion collisions. These measurements will allow one to understand
heavy quark energy loss and flow in heavy-ion collisions, contributions
of prompt production and quark recombination to vector meson production,
separation of initial-state and final-state modifications to charmonium
production, and provide important reference measurements from Drell-Yan.

### Energy Loss and Flow of Heavy Quarks

One of the most significant physics results in the first several years
of RHIC operations was the strong suppression of high-p~T~ light
particle production, shown in Figure 2, that is interpreted as energy
loss in dense matter for the outgoing particles or jets. A large
elliptical flow (asymmetry with respect to the reaction plane) is also
seen for the light hadrons as shown in Figure 3.

![](media/image5.png){width="3.123611111111111in"
height="2.1333333333333333in"}

[]{#__RefHeading___Toc119116921 .anchor}Figure 2 - Suppression of
high-p~T~ hadrons and pions as seen in Au+Au vs d+Au.

![](media/image6.png){width="3.002083333333333in"
height="2.9881944444444444in"}

[]{#__RefHeading___Toc119116922 .anchor}Figure 3 - Large elliptic flow
for light hadrons in Au+Au collisions is near the hydro limit .

More recent measurements are beginning to give some evidence that even
heavy quark (charm and beauty) suffer substantial energy loss in the
final state (see Figure 4) (Error: Reference source not found) and even
appear to flow, though the flow measurements at high pT are rather
imprecise and even somewhat inconsistent between the PHENIX and STAR
measurements (es (Error: Reference source not found). These results have
primarily come from the central rapidity detectors although some early
results from the muon spectrometers are beginning to emerge. But for all
these measurements large backgrounds and the necessity to calculate
non-heavy-quark contributions to the single lepton spectra and then
statistically subtract these to isolate the heavy-quark component with
low signal/background ratios give large systematic errors and limit the
accuracy of these measurements. Also there is not a clean way to
separate the charm and beauty components of the resulting subtracted
spect

![](media/image7.png){width="2.875in" height="2.796527777777778in"}

[]{#__RefHeading___Toc119116923 .anchor}Figure 4 - In PHENIX preliminary
results shown at QM05, even charm seems to suffer energy loss at
mid-rapidity.

![](media/image9.jpeg){width="2.745833333333333in"
height="2.5284722222222222in"}

[]{#__RefHeading___Toc119116924 .anchor}Figure 5 - Preliminary results
for charm from single electrons in PHENIX and STAR shows flow for small
p~T~ and somewhat inconsistent for larger p~T~.

One can pose several important classes of questions related to the
interaction of heavy quarks with the hot-dense (QGP) matter created in
central heavy-ion collisions that will be addressed by the FVTX upgrade:

-   How does energy loss and flow differ between light and heavy quarks?

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-   What is the rapidity dependence of the suppression or energy loss of
    heavy quark production in heavy-ion collisions and how can one
    understand it taking into account the density and geometry of the
    hot-dense matter that is created. i.e. given the additional boost of
    heavy quarks in the forward direction and differences of the
    time-dependence of the hot-dense region in the longitudinal vs
    transverse directions, the rapidity dependence should characterize
    these differences and help us understand the dynamics and properties
    of the dense medium?

-   How will the flow at lower momentum or asymmetry with respect to the
    reaction plane change as one goes more forward and how can this be
    understood theoretically? This should be sensitive to the density
    left behind from the collision or stopping and its evolution, with
    differences between forward and mid rapidity.

-   Can the high p~T~ dependence of heavy quark production distinguish
    between large flow, hydrodynamical behavior and production without
    final state interactions \[? Is this a good summary of the Batsouli
    question?)

-   \[question that would be posed by Ivan's studies: can rapidity
    dependence help separate quark energy loss and fragmentation in the
    medium effects ??\]

Predictions before the most recent data were that heavy quarks would not
lose much energy in hot-dense matter due to the \"dead-cone\" effect[^1]
but this appears inconsistent with the emerging results. Recent studies
suggest that the magnitude of the dead-cone[^2]^,^[^3]^,^[^4] may be
smaller than anticipated in reference Error: Reference source not found,
which would lead to an energy-loss for heavy quarks closer to that for
light quarks. Djordjevic and GyulassyError: Reference source not
found^,Error:\ Reference\ source\ not\ found^ have proposed that the
energy-loss for heavy-quarks is further reduced due to a plasmon
frequency cut-off effect in a thermalized medium. As a result precise
measurement of heavy-quark energy loss through open charm may enable a
measurement of partonic effective thermal masses in the medium. \[need
to check the rapidity dep of these predictions\]

At the opposite extreme, Batsouli *et al*[^5] have suggested that the
first electron measurements at RHIC, which showed N~Binary~ scaling of
heavy quark production in AuAu collisions, can be reproduced by assuming
that charm particles flow hydro-dynamically, i.e. the charm particles
interact with the medium with a large cross-section. To distinguish
between these effects and to explore this physics will require precisely
measuring the *p*~T~ spectra for open charm at high transverse momentum,
out to several GeV/c. This point is illustrated in Figure 6. The figure,
taken from reference Error: Reference source not found, illustrates that
the *p*~T~ distribution of *D* mesons and single electrons from charm
have little difference in the two extreme scenario of no medium effect
(shown in dashed curves) and hydrodynamic model (shown in solid curves)
within the *p*~T~ range accessible by the current PHENIX setup.
Obviously, a much more precise measurement at much higher *p*~T~ range
is required to distinguish the models. Such a measurement is not
feasible without the FVTX and VTX upgrades due to the large backgrounds
and ambiguity of charm and beauty contributions. \[measuring Ds helps
more. Should we address this\].

![](media/image10.jpeg){width="4.054166666666666in"
height="3.438888888888889in"}

[]{#__RefHeading___Toc119116925 .anchor}Figure 6 - Single electron data
of PHENIX compared with two extreme models of charm p~T~ distribution.
From ref. Error: Reference source not found.

Other theoretical pictures[^6] suggest that heavy and light quarks will
look quite different because the heavy quarks will fragment or hadronize
within the dense matter, while the light quarks will fragment outside.
So for the heavy quarks the process is more complicated with both quark
energy loss and fragmentation occurring in the medium. This behavior
would presumably depend on the rapidity of the observed leading
particles or jets and the large coverage in rapidity provided by the
FVTX will be quite important.

\[Similarly the flow of light particles shows what? And how the shape
would change for heavy-quarks?\]

Clearly the FVTX detector upgrade will be critical in helping to
determine which of the above theoretical pictures are reflected by the
real data as it will provide much more precise heavy quark cross section
and flow measurements, combined with the VTX will cover a very large
rapidity range, will much improve the p~T~ coverage at forward rapidity,
and will allow for separation of charm and beauty components to the
heavy quark spectra.

### Open charm and Beauty Enhancement

\[the following extracted from the VTX proposal, but seems pretty weak
to me?\]

It has been predicted that open charm production could be enhanced in
high-energy nucleus-nucleus collisions relative to the expectation from
elementary collisions[^7]^,^[^8]^,^[^9]. Heavy quarks are produced in
different stages of a heavy ion reaction. In the early stage charm and
beauty are formed in collisions of the incoming partons. The yield of
this component is proportional to the product of parton density
distribution in the incoming nuclei (binary scaling). If the gluon
density is high enough a considerable amount of charm can be produced
via fusion of energetic gluons in the pre-equilibrium stage before they
are thermalized. Finally, if the initial temperature is above 500 MeV,
thermal production of charm can be significant. The last two mechanisms
(pre-equilibrium and thermal production) can enhance charm production
relative to binary scaling of the initial parton-parton collisions.
These are the same mechanisms originally proposed for strangeness
enhancement, but in the case of charm may reveal more about the
critical, early partonic-matter stage of the reaction since the rate of
heavy-quark production is expected to be negligible later in the
reaction when the energy density has decreased. In comparison,
strangeness production is expected to continue even in the later
hadronic stages of the reaction.

![](media/image11.jpeg){width="2.7222222222222223in"
height="3.0375in"}![](media/image12.jpeg){width="2.428472222222222in"
height="2.9763888888888888in"}

[]{#__RefHeading___Toc119116926 .anchor}Figure 7 Charm enhancement
expected at RHIC energy from ref. Error: Reference source not found. In
both panels, contribution from the initial gluon fusion (solid),
pre-thermal production (dot-dashed), and thermal production (dashed,
lowest) are shown. The left panel is the calculation with energy density
of 3.2 GeV/fm^3^, while the right panel shows the case with energy
density 4 times higher.

At RHIC energies the anticipated enhancement is a small effectError:
Reference source not found^,Error:\ Reference\ source\ not\ found^. The
contributions to charm production from various stages ofan Au+Au
collision are shown in Figure 7 (taken from reference Error: Reference
source not found). From the left panel of the figure it is evident that
for an initial energy density of 3.2 GeV/fm^3^ the pre-thermal or
pre-equilibrium production contributes about 10% of total charm
production, while the thermal contribution is negligible. However, the
yield is very sensitive to the initial density, and with 4 times the
energy density the pre-equilibrium contribution can be as large as the
initial fusion. This is illustrated in the right panel of the figure.
Present single electron measurements of PHENIX indicate that within
\~25% systematic uncertainty charm production approximately scales with
the number of binary collisions. Thus, charm enhancement, if it exists,
cannot be a large effect. A measurement of the charm yield with
substantially higher accuracy and precision is therefore required to
establish a potential charm enhancement.

The FVTX combined with the muon spectrometers will allow measurement of
charm and beauty over a much broader range in *p*~T~. This will extend
the single muon measurement to the *p*~T~ region near 0.5 GeV/c, which
is essential for an accurate determination of the *p*~T~ integrated
charm yield at forward and backward rapidities since more than half of
the yield from charm decays is in this *p*~T~ region. Combined with the
central rapidity (\|y\|\<1.2) measurement from the VTX detector -
approximately one third of the total charm cross section is expected to
come from the rapidity range measured by the FVTX as shown in Figure
1Figure 7- this will allow an accurate measurement of the total charm
cross section which can then allow us to see a potential charm (or
beauty) enhancement.

![](media/image13.jpeg){width="4.376388888888889in"
height="3.3583333333333334in"}

[]{#__RefHeading___Toc119116927 .anchor}Figure 8 - Rapidity
distribrution from Vogt[^10] for charm in pp collisions at s = 200 GeV.
Roughly half the total cross section comes from the region of the FVTX
coverage, \|y\|\>1.2

### J/ Suppression and Comparisons with Open charm, ' and 

J/ production in heavy ion collisions is a complicated process which can
be both difficult to disect but also allow the possibility to understand
several features of heavy ion collisions at the same time if the
measurement is precise enough and it is used in conjunction with other
relevant measurements, such as open charmproduction. J/ production can
be modified in AuAu collisions with respect to pp collisions by
modification of the gluon distribution functions in a nucleus, energy
loss of the composite quarks in the medium, contributions to the
production from both prompt production and recombination if the charm
density is high enough, as well as the historical prediction of
suppression due to Debye screening in a plasma. To quantitatively
understand suppression/enhancement requires knowledge of the initial
production of $c\overline{c}$pairs and the affect of cold nuclear matter
on production. The effectiveness of a deconfined medium in preventing
the formation of J/ can be quantified using the ratio J//(open charm) in
the same acceptance as PHENIX measures J/The FVTX upgrade provides for
the detection of open charm over about the same rapidity interval as for
J/ decays to dimuons. In addition, the J/ measurements alone are
currently limited in AuAu interactions by the amount of background that
must be subtracted from the J/ peak, even with a reduced detector
acceptance running which we have employed to reduce the backgrounds. The
addition of the FVTX will greatly enhance the J/ measurement in the
forward region by mostly eliminating the combinatorial background that
comes from pion and kaon decay muons and by improving the mass
resolution (see Figure 9) by providing an accurate measurement of the
dimuon opening angle.

The measurement of the production of ' and will also greatly improve the
understanding of J/ production as they each have large and smaller Debye
screening lengths, respectively, production allows comparison of beauty
production to charm production, and the ' shares much of the same
production issues as the but does not suffer from feed-down from other
states. These, combined with open charm measurements, should allow for
separation of initial state and final state modifications to J/
production.

### 

#### 

#### 

#### 

### 

![](media/image14.png){width="4.117361111111111in"
height="2.7729166666666667in"}

[]{#__RefHeading___Toc119116928 .anchor}Figure 9. Mass spectra for the
J/ and \', showing the substantial improvement in separation expected
with a vertex detector (yellow, 100 MeV resolution) compared to that
without a vertex detector (black, 150 MeV resolution). The number of J/
and ' in this plot represents our expectation for a \~25 pb^-1^ p+p run.

### Drell-Yan

### 

### Improvement in the Reaction Plane Resolution

\[The large increase in the overall solid angle for observing charge
particles provided by the FVTX (plus more optimal rapidity coverage?)
will also give a substantial improvement in the reaction plane
resolution which will aid in the study of many signals in PHENIX versus
reaction plane Many physics measurements made by PHENIX with respect to
the reaction plane are more limited by the reaction plane resolution
than by other systematics or statistics, so this is a critical
improvement to the PHENIX physics program.\]

## Proton(Deuteron)+Nucleus Collisions and Nuclear effects on Gluons in Nuclei

Proton-nucleus collisions not only provide important baseline
information for the study of QCD at high temperatures, they also address
fundamental issues of the parton structure of nuclei. Since the
discovery of the EMC effect in the 1980\'s, it is clear that the
parton-level processes and structure of a nucleon are modified when
embedded in nuclear matter[^11]. These modifications reflect fundamental
issues in the QCD description of the parton distributions, their
modifications by the crowded nuclear environment of nucleons, gluons and
quarks, and the effect of these constituents of the nucleus on the
propagation and reactions of energetic partons that pass through them.

### Gluon saturation via Heavy-quarks

Of particular interest is the depletion in nuclei of low momentum
partons (gluons or quarks), called shadowing, which results from the
large density of very low momentum partons. For gluons at very low
momentum fraction, *x* \< 10^-2^, one can associate with them, following
the uncertainty principle, a large distance scale. These high-density
gluons then will interact strongly with many of their neighbors and by
gluon recombination or fusion are thought to promote themselves to
larger momentum fraction, thus depleting small values of *x*. In most
pictures the overall momentum is conserved in this process and so the
small *x* region gluon density is depleted while the moderate *x* region
above that is enhanced. Recently years a model for gluon saturation at
small *x* has been discussed extensively by McLerran and
collaborators[^12]. Gluon saturation affects both the asymptotic
behavior of the nucleon gluon distributions as *x* approaches zero and
causes shadowing.

![](media/image15.png){width="4.079861111111111in"
height="2.6381944444444443in"}

[]{#__RefHeading___Toc119116929 .anchor}Figure 10 - Gluon shadowing from
Eskola as a function of x for different Q2 values: 2.25 GeV^2^ (solid),
5.39 GeV^2^ (dotted), 14.7 GeV^2^ (dashed), 39.9 GeV^2^ (dotted-dashed),
108 GeV^2^ (double-dashed) and 10000 GeV^2^ (dashed). The regions
between the vertical dashed lines show the dominant values of *x~2~*
probed by muon pair production from *dd*bar at SPS, RHIC and LHC
energies.

At RHIC energies many of the observables are affected by gluon
distributions at small *x* where nuclear shadowing is thought to be
quite strong. However, theoretical predictions of the amount of
shadowing differ by factors as large as three. For example, in the
production of J/\'s in the large rapidity region covered by the PHENIX
muon arms, models from Eskola et al (Figure 10) predict only a 30%
reduction due to gluon shadowing, while those of Frankfurt &
Strikman[^13] or Kopeliovich[^14] predict up to a factor of three
reduction.

![](media/image16.jpeg){width="3.6958333333333333in"
height="3.501388888888889in"}

[]{#__RefHeading___Toc119116930 .anchor}Figure 11 - J/ψ nuclear
dependence versus rapidity compared to theoretical predictions with
several types of gluon shadowingError: Reference source not found.

Recent measurements by PHENIX of the J/ψ nuclear dependence for d+Au
collisions[^15] are shown in Figure 11 and show weaker absorption and
shadowing than expected. The large rapidity region corresponds to small
momentum fraction in Au, the region where shadowing is thought to be
important. Extraction of gluon densities from these measurements is not
only hampered by the poor statistical precision of the present d+Au
data, but also by theoretical issues including the possibility that much
of the suppression at large rapidity might come from either
initial-state energy loss of the gluon from the projectile[^16] or from
Sudakov suppression effects on the final-state c-cbar[^17]. Increased
statistics from higher luminosity runs and more definitive measurements
via observables that are sensitive to gluon structure functions in
several different channels will be necessary to test the theory with
sufficient power to constrain the underlying QCD processes.

![](media/image17.jpeg){width="5.001388888888889in"
height="3.714583333333333in"}

[]{#__RefHeading___Toc119116931 .anchor}Figure 12 Alpha versus x~2~ and
x~F~ from measurements at three different energies shows that the
suppression does not scale with x~2~ but does exhibit approximate
scaling with x~F~. Alpha is defined as
$\sigma_{A} = \sigma_{p}A^{\alpha}$, where $\sigma_{p}$($\sigma_{A}$) is
the nucleon (heavy nucleus, A) cross section. Data is from PHENIX (s =
200 GeV/c)Error: Reference source not found, E866/NuSea (s = 39
GeV/c)[^18] and NA3 (s = 19 GeV/c)[^19].

\[Discussion of lack of x2 scaling and scaling with xF instead.\]

Earlier data from lower-energy fixed-target p+A measurements at Fermilab
are shown in Figure 12. They show much stronger suppression at large
x~F~ (or small x~2~), where x~2~ is the momentum fraction of the gluon
in the nucleus and x~F~ = x~1~ - x~2~ (x~1~ being the momentum fraction
of the gluon from the proton projectile). A stronger absorption at
mid-rapidity than observed more recently at PHENIX is also apparent. A
comparison of the results at PHENIX, E866/NuSea at Fermilab, and NA3
versus x~2~ or x~F~ is shown in Error: Reference source not found.

===============================================================

In particular, it is clear that a precise knowledge of the shadowed
gluon structure functions in nuclei is essential towards understanding
several of the important signatures for QGP in heavy-ion collisions at
RHIC, including open and closed heavy-quark production. Recombination
models for J/ production, which might cause an enhancement of that
production in heavy-ion collisions due to the large density of charm
quarks created in a collision, must be constrained by an accurate
measurement of the amount of charm produced given the shadowing of the
gluon densities in the colliding nuclei.

In the J/ studies done at CERN by NA38/50[^20] the J/ yields were
usually divided by the Drell-Yan dimuon yields, since the latter should
have little nuclear dependence. But this is actually an unnatural
procedure since the Drell-Yan process involves quarks (q-qbar
annihilation) while J/ production involves gluons (gluon fusion). The
nuclear effects on the initial parton distributions for quarks and
gluons are likely different and their energy loss in the initial state
before the hard interaction also likely different. Additionally the
yields of Drell-Yan dimuon pairs were quite small at CERN and dominated
the statistical uncertainties in this ratio. The rates for Drell-Yan at
PHENIX are even smaller and making such a ratio makes even less sense
here. It is much more natural to compare J/ production to open-charm
production, where the initial-state effects are probably the same.
Therefore a robust measurement of open-charm is quite important for the
physics of the J/. Of course, it has also been suggested by some
theoretical groups[^21] that the effective gluon distributions are
process dependent, and different for e.g. open- and closed-charm
production. These models suggest that such a difference, if seen by
comparisons of open and closed charm, would indicate that higher-twist
contributions to closed charm production were substantial.

Another area of importance, especially to the J/ measurements, is the
production of beauty quarks. The decay of B-mesons will produce J/'s (BR
\~ 1.14%) that tend to have somewhat higher p~T~ than prompt J/
production. In a scenario where color-screening in a QGP created in
heavy-ion collisions destroys most of the J/'s it is conceivable that,
particularly at higher p~T~, the remaining J/'s become dominated by
those that come from B decays. An estimate of this from Lourenco[^22]
several years ago indicated that for central collisions the fraction of
J/'s from B decays might be as large as 20% overall, with even larger
fractions at high p~T~. Clearly one would like to measure the B cross
sections at RHIC energies so that a more reliable estimate of their
contribution to the J/ production can be made, an issue which would be
particularly important should a large suppression of J/'s be seen in
central Au-Au collisions at RHIC. How strong a suppression is actually
occurring would be difficult to know without establishing how many of
the remaining J/'s do come from B decays. In addition, given sufficient
RHIC luminosity, it would be quite instructive to measure for beauty the
same observables already discussed for charm, and to compare these
results. As RHIC luminosity increases we will also be able to measure
the Upsilon, a b-bbar bound state; and for it, a comparison with
open-beauty will obviously be important.

A number of other physics issues besides shadowing also need to be
understood. Energy loss of partons in the initial state is thought to
have a small effect at RHIC since the energy loss per fm, in most
models, is thought to be approximately constant and small compared to
the initial-state parton energies at RHIC. On the other hand, partons in
the final state could show some effects of energy loss since their
momentum is lower, while heavy-quarks are expected to lose less energy
than light partons due to the dead-cone effect[^23]. These issues are
very important in the high-density regions created in heavy-ion
collisions, but need a baseline for normal nuclear densities from
proton-nucleus collisions. Another general feature of most produced
particles comes from the multiple scattering of initial-state partons,
which causes a broadening of the transverse momentum (Cronin effect) of
the produced particles.

Many of the present measurements of the observables necessary to address
these critical physics issues are weakened by the lack of a more
exclusive observation of the process. For example, our present
capability for identifying open-charm is via high-p~T~ single leptons
(electrons or muons) and relies on the fact that the leptons at higher
p~T~ come mostly from heavy quarks (charm or beauty) and on a
subtraction of a large amount of background from light-meson decays.
This procedure suffers from large uncertainties due to the limited
knowledge of the background sources that are subtracted and also pushes
one towards higher p~T~ where the yields for a given luminosity are
smaller. The addition of a silicon vertex detector to PHENIX would allow
for a much more convincing and accurate determination of the heavy-quark
component in these spectra and also allow measurement to smaller p~T~
values by substantially reducing the low-mass meson decay backgrounds.
Figure 13 andFigure 144 show a simulation of the single muon spectra
with contributions from charm, beauty and background decays with and
without the use of detached vertex identification from a silicon vertex
detector.

![](media/image18.png){width="2.626388888888889in"
height="2.626388888888889in"}

[]{#__RefHeading___Toc119116932 .anchor}Figure 13 - Single muon p~T~
distributions for charm, beauty and backgrounds from low-mass meson
decays.

![](media/image19.wmf){width="2.5069444444444446in"
height="2.5694444444444446in"}

[]{#__RefHeading___Toc119116933 .anchor}Figure 14 - Single muon p~T~
distribution for charm compared to backgrounds with a vertex cut showing
signal/noise well above one even at p~T~=0.5 GeV/c.

While Figure 15 and 6 show a similar improvement for electrons in the
central rapidity region when a vertex detector can be used to cut on the
distance of closest approach (DCA) of the electrons to the primary
vertex.

![](media/image20.png){width="3.002083333333333in"
height="2.5194444444444444in"}

[]{#__RefHeading___Toc119116934 .anchor}Figure 15 - Single electron pT
spectrum without a vertex detector.

![](media/image21.png){width="2.622916666666667in"
height="2.5909722222222222in"}

[]{#__RefHeading___Toc119116935 .anchor}Figure 16 -- Distance of closest
approach (DCA) distribution for heavy-quark and backgrounds showing how
backgrounds can be greatly reduced by a vertex detector which allows
cuts on the DCA.

In general, all processes suitable for the measurement of gluon spin
structure in nucleons are also ideal for probing the gluon distributions
in nuclei. The reach in Bjorken *x* is indicated in Figure 17Error:
Reference source not found, superimposed on calculations of the ratio of
nuclear to nucleon gluon structure functions.

![](media/image22.png){width="4.034722222222222in" height="3.15625in"}

[]{#__RefHeading___Toc119116936 .anchor}Figure 17 - Gluon shadowing
predictions along with PHENIX coverage. The red bars indicate the
additional range provided by the vertex upgrade, while the blue bars
cover the PHENIX baseline. The three theoretical predictions are for
different Q transferred, blue, green and red lines are *Q* = 10, 5 and 2
GeV/c respectively, from Frankfurt and Strikman[^24].

The red bars indicate the additional coverage provided by the vertex
upgrade compared to the baseline of PHENIX. The vertex upgrade extends
the *x*-range from the anti-shadowing region into the shadowing domain
and therefore will provide a measurement of shadowing and establish the
shape of the shadowed structure functions versus *x*.

Drell-Yan measurements, which provide a direct measure of the anti-quark
distributions in nucleons or nuclei, have always been limited in the
past in their reach to low *x* by the inability to separate the
Drell-Yan muon pairs below the J/ in mass from copious pairs from
open-charm decays in that mass region. For example, in FNAL E866/NuSea,
information extracted from the Drell-Yan process was limited to masses
above 4 GeV.

![](media/image23.png){width="4.843055555555556in"
height="2.3361111111111112in"}

[]{#__RefHeading___Toc119116937 .anchor}Figure 18 - Dimuon mass spectrum
from E866/NuSea showing the mass region used in their analysis which
excludes masses below 4 GeV. Lower masses were excluded because of the
large backgrounds from open charm in that region.

=================================================================

On the other hand, PHENIX, with the addition of a vertex detector,
should be able to identify and quantify the portion of the lower mass
dimuon continuum from charm decays and therefore isolate the Drell-Yan
process at these lower mass and lower *x* values. In the
central-rapidity barrel region values as low as *x~2~* \~ 0.7×10^-2^
could be accessed. This will still be a challenge because of the small
cross sections and yields for Drell-Yan at RHIC, but has the potential
of providing information on the anti-quark distributions at much smaller
values of *x*. At the same time one would also learn more about charm
production and the correlation of the charm pairs through the charm
pairs found in the continuum.

In summary, the silicon vertex barrel, which covers the PHENIX central
arm mid-rapidity range ( \|*y*\| \< 0.35 ), addresses the following
physics in dA reactions :

-   Charm and beauty at high *p*~T~ and mid-rapidity via high-*p~T~*
    electrons and also exclusive decays such as $D \rightarrow K\pi$ and
    $D \rightarrow K\text{ππ}$.

-   A gluon structure measurement in the anti-shadowing region as a
    baseline for shadowing measurements at small *x*.

-   Charm measurements at mid-rapidity as a baseline for J/ production,
    i.e. for comparisons of open and closed charm which should share the
    same initial-state effects in nuclei.

-   Accurate measurement of nuclear dependence of charm cross section

-   Beauty cross sections at mid-rapidity as a constraint on the
    contributions of $B \rightarrow \frac{J}{\psi}$to J/production.

-   Comparison of light and heavy-quark *p*~T~ distribution to determine
    differences in energy loss and Cronin effects.

-   Better separation in high-luminosity measurements of measurements of
    the three states.

-   Low-mass electron pairs and anti-quark shadowing at small *x*
    values.

The reach in *x*-range for the Si Endcap is indicated in 4, superimposed
on calculations of the ratio of nuclear to nucleon gluon structure
function. The red bars indicate the additional coverage provided by the
Endcap vertex upgrade compared to the baseline of PHENIX. The Endcap
vertex upgrade provides extends the *x*-range from the anti-shadowing
region into the shadowing domain, which means we will be able to
establish the shape of the gluon structure function in nuclei. The
shadowing region is not accessible with the Barrel-only upgrade. While
the *x*-range for J/production also extends into the shadowing range,
final state effects, such as dissociation, complicate the extraction of
the gluon structure function. Open charm and beauty measurements are
unaffected by these final state effects.

![](media/image24.png){width="4.034722222222222in"
height="3.3833333333333333in"}

[]{#__RefHeading___Toc119116938 .anchor}Figure 19. Gluon shadowing
predictions along with PHENIX coverage. The red bars indicate the
additional range provided by the Endcap vertex upgrade, green bars are
for the barrel upgrade, while the blue bars cover the PHENIX baseline.
The red and blue curves are theoretical predictions of shadowing from
EKS and FKS for different Q values.

The FVTX provides coverage in gluon momentum fraction (x) through
measurements of heavy-quarks (charm and beauty) and through their bound
states (J/ψ, ψ\' and ).

### Baseline for Nucleus-Nucleus

### Disentangling the physics of J/ψ

## Polarized Proton Collisions and the Gluon Spin Structure of the Nucleon

PHENIX has the existing capability shown in 3 as the blue lines. However
there are significant gaps in this *x*-range that will make it difficult
to fully address the spin-crisis. The proposed Si Endcap detector
extends the coverage to the lowest and highest *x*-values, 0.001 \< *x*
\< 0.3, as well as providing significant regions where multiple channels
overlap. This overlap will provide vital cross-checks that will improve
the reliability of global fits to the spin structure function.

![](media/image25.png){width="4.159027777777778in" height="3.4in"}

[]{#__RefHeading___Toc119116939 .anchor}Figure 20. Expected x-range for
different channels used to extract the gluon spin structure function.
The blue bars indicate PHENIX's existing capability, green bars are for
the Barrel upgrade, while the red bars indicate the additional coverage
provided by the p roposed Endcap vertex upgrade. The curves show various
estimates of the expected gluon polarization.

The Endcap vertex detector provides the following improvements in
x-range over a Barrel only detector. These have been estimated by
simulating *p+p* collisions with PYTHIA and requiring sufficient counts
in each exit channel to be able to make a reasonable measurement.

-   $c\overline{c}$production via gluon fusion. The x-range is extended
    considerably down to *x* = 0.001 using $D \rightarrow \mu X$.

-   $b\overline{b}$ production via gluon fusion. With the upgrade we can
    identify displaced J/ from $B \rightarrow \frac{J}{\Psi}$ decay.
    This provides coverage in x between 0.005 - 0.3. The selection of
    semi-leptonic decays $b\overline{b} \rightarrow e\mu X$ at high
    momentum is improved using displaced vertices. This extends the
    *x*~gluon~ coverage for these semi-leptonic decays to 0.01 - 0.3.
    Measurement of $B \rightarrow \mu X$ is also possible by placing a
    cut on the *p*~T~ of the muon.

.

# Simulations and Required Performance for the Si Endcap Upgrade

The performance requirements for the Si Endcap detector are :

> Ability to match tracks from a muon arm to hits in multiple layers of
> the Si detector.

a.  Sufficient position accuracy so that the displacement resolution of
    the track with respect to the collision point is less than the c of
    charm and beauty decays, i.e. a resolution less than 100m,
    preferably at the level of 30 - 50 m.

b.  Good resolution in both r and z are required.

c.  Sufficient segmentation to operate well in Au-Au and high luminosity
    p+p collisions.

For the simulations we have used two nominal thickness for each layer:
1% and 2% radiation length. This includes detector, readout and cooling
in a simplified one-volume effective layer. Our current concept will
have a radiation length close to 1% because we are implementing a design
that has incorporated a readout bus in the silicon chips and sensors and
we are able to thin the chips. We are striving to minimize this
thickness, in particular for the critical first disk.

The endcaps mini-strips vary in size from 50m by 2000m to 50m by 9000m
as the radius increases. This keeps the occupancy at or below 1.5%.

## Open Charm Measurement

> **Si Endcaps:** $D \rightarrow \mu X$**,**
> $D\overline{D} \rightarrow \mu\text{eX}$**,**
> $D\overline{D} \rightarrow \mu^{+}\mu^{-}X$

Each silicon endcap detector has four layers of pixel detectors, which
measure the trajectory of particles within the nominal rapidity
acceptance of the muon arms. The impact parameter of each track is
determined accurately along the Z (beam) direction. For each detected
muon, the impact parameter is used to eliminate muons that come from
pion and kaon decays. These long-lived decays are the primary source of
background muons.

Contrasted with these background muons are \"prompt\" single muons,
which come from more short-lived decays, e.g. open charm and beauty. For
transverse momenta below \~5 GeV/c the prompt muons are primarily from
semi-leptonic charm decay. Other processes that produce prompt muons,
such as J/or Drell-Yan decays to muon pairs, have much smaller
cross-sections times branching ratios. Muons from *B* decays become
important only at larger transverse momenta.

The PYTHIA event generator was used to simulate semi-leptonic charm
decays to muons. The total charm pair cross-section was set at 350 µb,
which is consistent with recent NLO theoretical calculations and with
the published PHENIX measurement at a somewhat lower energy. The decay
muons were tracked through the proposed silicon vertex detector and then
through the muon spectrometer using PISA.

The mean vertex of the detected muons from charm decay is 785m from the
interaction vertex. This is \~2.5 times larger than the proper decay
length of semi-leptonic charm decays (m), due to the Lorentz boost. The
impact parameter resolution for these muons ranges from 92 to 115 m,
depending on how many layers of silicon are transversed. By requiring
that the muon vertex is within 1cm of the collision point we remove many
of the muons from pion and kaon decay while retaining prompt muons from
charm and beauty.

6 shows a simulated muon *p*~T~ spectrum, including charm, beauty and
light quark decays, before the application of a vertex cut. The
background from light quark decays dominates the spectrum below 4 GeV/c.
The *p*~T~ distribution of muons that survive a 1 cm vertex cut is shown
in 7. This vertex cut reduces the muon background from light mesons by
about an order of magnitude over what the muon arm alone can achieve,
making a charm measurement possible even at low *p*~T~. Note that the
removal of the muon background from pion and kaon decays could be
achieved with a detector with less spatial resolution. The resolution
requirement is driven by the physics program of measuring open beauty
(see next section).

![](media/image26.png){width="3.8916666666666666in" height="2.79375in"}

[]{#__RefHeading___Toc119116940 .anchor}Figure 21. Single muon p~T~
distributions for charm, beauty and backgrounds from low-mass meson
decays, as expected for the 2003 d+Au run. Note that the light-meson
decays are above charm up to near 4 GeV/c. The black curve is for pion
and kaon decays, green is charm and red is beauty.

![](media/image27.jpeg){width="3.682638888888889in"
height="3.682638888888889in"}

[]{#__RefHeading___Toc119116941 .anchor}Figure 22. The p~T~ distribution
of muons that decay within 1 cm of the collision vertex. The red
histogram is for charm decays while the black is for pion and kaon
decays.

To calculate the yield of charm, we assume a 650 µb D pair
cross-section, integrated *p+p* luminosity on tape of 50 pb^-1^. A total
of about 10^8^ semi-leptonic charm decays would be reconstructed. This
rate is before application of a vertex or impact parameter cut. Even if
a large pre-scale is required for single muon triggers, the yield is
still very large.

Since charm is produced in pairs, coincidence measurements of
opposite-sign lepton pairs may serve to further enhance the signal to
noise in *p+p* and *p+A* reactions. One could use vertex identified
muon-electron coincidences to obtain a clean charm pair signal in the
rapidity interval midway between the PHENIX central and muon arms.

## Open Beauty Measurement

B meson production, while much more rare than *D* production, is
somewhat simpler to measure. The challenge is the relatively low rate.
There seem to be at least two possibilities :

-   Since beauty mesons have a larger lifetime than charm mesons, it is
    possible to extract the beauty yield from the distribution of decay
    distances of single muons from semi-leptonic decays. At large
    transverse momentum beauty decays dominate the DCA distribution.

-   The decay channel *B* J/+X produces J/s that are displaced from the
    collision point.

**Si Endcaps:**
$B \rightarrow \frac{J}{\psi} \rightarrow \mu^{+}\mu^{-}$**,**
$B \rightarrow \mu X$

Applying a vertex cut on each reconstructed J/ has been used
successfully to identify B-production in experiments at lower
energies[^25]. Since the B cross-section is larger at RHIC energies, the
measurement should be easier. As the average p~T~ of J/ from beauty
decays is larger than for prompt J/, a p~T~ cut could also be used to
enrich the beauty sample.

Pythia was used to simulate
$B \rightarrow \frac{J}{\psi} \rightarrow \mu^{+}\mu^{-}$ decays. The
resulting muons are tracked through the silicon and muon spectrometers
using PISA. The muons have an impact resolution of \~55 m, significantly
better than muons from D decays, due to their larger average momentum.
The pair z-vertex resolution is \~133 m, while the mean decay length is
\~1.1mm. With a downstream pair z-vertex cut of 1 mm, 39% of the B
decays are retained, while the prompt J/ are attenuated by a factor of
2x10^-4^. 8 shows the reconstructed Z-vertex distribution for the J/
from B decays as well as prompt J/.

![](media/image28.jpeg){width="3.5145833333333334in"
height="3.3930555555555557in"}

[]{#__RefHeading___Toc119116942 .anchor}Figure 23. The reconstructed
Z-vertex distribution for J/ from B decays (black line) and for prompt
J/ (red line). Note that the J/ yield has been scaled down by a factor
of 100. The relative yield of J/ from B decays versus prompt J/is
estimated to be about 1%.

We have assumed a total B cross-section of 2 microbarns and 4 microbarns
for J/production. The branching ratio of 1.2% for
$B \rightarrow \frac{J}{\Psi}$ has been previously measured. The total
acceptance \* BR for these events using two Si Endcaps is \~
4.0\*10^-5^. Assuming an integrated luminosity to tape of 50 pb^-1^,
about 1900 $B \rightarrow \frac{J}{\Psi}$ events would be reconstructed
after the application of a 1 mm vertex cut. For $B \rightarrow \mu X$,
the acceptance \* BR is \~ 0.0087. The corresponding yield is \~780,000
reconstructed events. Thus, an excellent *B* measurement is possible.

## Trigger Plans

We plan to use the level 1 single and di-muon triggers as the main
physics trigger for the Si Endcaps. Higher level triggers could be a
level 2 displaced track trigger, possibly similar to the trigger used by
CDF and E789. Both CDF and E789 implemented the trigger in hardware to
optimize it for speed. For PHENIX this could be ported to level 2. The
algorithm for the Si Endcaps / muon spectrometers would be very similar
to that done previously by E789.

The E789 algorithm functions in three steps (translated into PHENIX
language); 1) Muon tracks are found from stubs in the Muon ID and Muon
Tracker. The momentum and angle of each track are determined. 2) These
tracks are then matched to hits in the Si Endcap using a pre-computed
lookup table. 3) Si hits within the matching window are formed into a Si
track stub. The stub is then fitted with a straight line to determine
the momentum, angle and impact parameter of the track.

These events would then be passed to the level 2 triggers of displaced
vertexes and/or high-momentum tracks. For pair triggers, tracks could be
combined and fitted to determine a pair vertex.

## Si Endcap Event Rates

The event yields in the previous sections are summarized below. They
assume an integrated p+p luminosity on tape (for Run 10) of 50 pb^-1^.
Yields from a comparable Au-Au run would be about a factor of 3X lower.
The yields for semileptonic heavy quark decays are about an order of
magnitude larger than for the Si Barrel, due to the larger acceptance of
the Si Endcap. The *B* decay rates could benefit from the increased
luminosity in the RHIC II proposal.

[]{#__RefHeading___Toc119116958 .anchor}Table 1 -- Rates for RHIC p+p.

  ------------------------------------------------------------- -----------------------------------
  Observable                                                    Counts per RHIC p+p Run 10

  $$D \rightarrow \mu X$$                                       \~ 10^8^

  $$B \rightarrow \mu X$$                                       780k

  $B \rightarrow \frac{J}{\Psi X} \rightarrow \mu^{+}\mu^{-}$   1900
  ------------------------------------------------------------- -----------------------------------

## Matching to Muon Spectrometers 

Track matching between the Si Endcaps and the Muon Spectrometers was
studied by using hijing Au-Au central collisions in a PISA simulation. A
muon track was embedded in a hijing event. The muon track was found in
station 1 from the muon tracker by demanding that the muon reached the
middle of the MUID, i.e. the muon energy was \> 2.5 GeV. The
distribution of the muon hits in station 1 was found to be +- 2 cm from
the projection of the Si Endcap track, due to multiple scattering in the
central magnet steel. No other track in the tracker was found to be in a
+- 2cm cut around the muon hit in station 1. We then looked for all
tracks in the Si Endcaps that had their projection fall into the 2 cm
cut about the muon track. In addition to the muon, typically 3 other
tracks fell into this cut. Of these candidate tracks all except the muon
came from the primary interaction vertex. The background would be the
fraction of primary tracks that fall beyond a 1 mm cut.

## Integration with PHENIX

The proposed Endcap vertex detector matches and extends the capability
of the existing muon spectrometer arms. In addition a TPC is being
proposed to sit outside the vertex detector. The Detector Advisory
Committee recommended studies exploring the impact of the VTX on the TPC
with the possibility of standalone running for either detector. Because
the Endcaps are outside of the acceptance of the HBD/TPC we believe that
both detectors can operate simultaneously.

# FVTX Detector system

## Overview

The FVTX detector system is composed of two identical endcap sections,
in the front of the north muon spectrometer and one in the front of the
south muon spectrometer. The two endcap sections are identical. A 3-D
model of the detectors is shown in 1 (and figure 1.) and the geometrical
parameters are shown in.1. The VTX detector consists of a barrel region
and the two endcap regions enclosed in an environmental enclosure. The
environmental enclosure is needed because the barrel detector must be
operated at 0 deg C. The enclosure radius is 20 cm except at the ends
where the enclosure extends out to 45 cm. The larger radius ends are
used for the barrel pixel layer transition electronics and for all of
the bus cables, power and cooling lines. Generally, the barrel uses 240
deg oe the surface area at the ends and the endcaps use 40 deg at the
top and bottom. The four endcap disks contain 48 individual wedge shaped
towers mounted on a carbon composite cooling substrate. Each wedge
contains silicon sensors with readout chips bump bonded to the sensors,
one on each side of the cooling substrate so that the acceptance is
hermetic in "r". Adjacent wedges overlap to give hermetic coverage in
"phi". The technology for the sensors are for conventional 50 m silicon
strip detector technology with the strips oriented so that the strips
nearest the beam pipe at a radius of 3.0 cm are short, \~2.0mm long in
the phi coordinate, and at the largest radius of 18 cm, \~ 12 mm long.
Individual strips fan out on from the center of the 7.5 deg wedge. The
maximum occupancy at the inner strip is 1% and reduces to XXX at the
largest radius. The total number of readout strips in each endcap is \~
0.760^5^10^6^. The PHX chips on each sensor are daisy chained to a
flexible kapton bus that takes the data outside of the enclosure.

![](media/image29.png){width="6.166666666666667in"
height="3.6979166666666665in"}

[]{#__RefHeading___Toc119116943 .anchor}Figure 24 - 3-D model of the
full vertex detector showing the barrel portion and the endcaps on left
and the endcap on the right. Also shown is the VTX mounting fixture.

[]{#__RefHeading___Toc119116959 .anchor}Table 2 - Summary of the
parameters of the FVTX disks.

operated at 0 deg C. The enclosure radius is 20 cm except at the ends
where the enclosure extends out to 45 cm. The larger radius ends are
used for the barrel pixel layer transition electronics and for all of
the bus cables, power and cooling lines. Generally, the barrel uses 240
deg of the the surface area at the ends and the endcaps use 40 deg at
the top and bottom. The four endcap disks contain 48 individual wedge
shaped towers mounted on a carbon composite cooling substrate. Each
wedge contains silicon sensors with readout chips bump bonded to the
sensors, one on each side of the cooling substrate so that the
acceptance is hermetic in "r". Adjacent wedges overlap to give hermetic
coverage in "phi". The technology for the sensors are for conventional
50 m silicon strip detector technology with the strips oriented so that
the strips nearest the beam pipe at a radius of 3.0 cm are short,
\~2.0mm long in the phi coordinate, and at the largest radius of 18 cm,
\~ 12 mm long. Individual strips fan out on from the center of the 7.5
deg wedge. The maximum occupancy at the inner strip is 1% and reduces to
XXX at the largest radius. The total number of readout strips in each
endcap is \~ 0.86 x 10^6^. The PHX chips on each sensor are daisy
chained to a flexible kapton bus that takes the data outside of the
enclosure.

![](media/image29.png){width="6.166666666666667in"
height="3.6979166666666665in"}

Figure 25 - 3-D model of the full vertex detector showing the barrel
portion and the endcaps on left and the endcap on the right. Also shown
is the VTX mounting fixture.

Table 3 - Summary of the parameters of the FVTX disks.

  --------------- ------------------- ------- --------- --------- ---------
  FVTX            Disk                Z1      Z2        Z3        Z4

  Geometrical     z (cm)              20.0    26.0      32.0      38.0

  dimensions      R (cm) inner        3.0     3.0       3.0       3.0

                  R (cm) outer        10.6    14.0      18.0      18.0

  Channel count   no of wedges        48      48        48        48

                  sensors/wedge       2       2         2         2

                  readout chips       6       8         11        11

                  Readout Channels            197k      270k      270k
                  147k                                            

  Radiation       Sensor (200 m)                                  
  Length                                                          

                  Readout (150 m)                                 

                  Bus                                             

                  Ladder&cooling                                  

                  total                                           
  --------------- ------------------- ------- --------- --------- ---------

## Silicon readout chip - PHX

A number of candidate chips for the readout of the endcaps were
investigated. Most were developed by the Fermi National Lab Electrical
Engineering Department, ASIC development group under the leadership of
Ray Yarema. We initially looked at the ALICE 1 LHCb chip being developed
for the LHCb beauty experiement. However, to cover the acceptance of the
muon arms would have taken \~33 x 10^6^ channels

FNAL Electrical Engineering Department, ASIC development group (Group
leader, Ray Yarema) has designed the FPIX2 chip, a low-noise
programmable Si pixel readout chip for the former BTeV experiment. The
chip is an advanced mixed analog/digital DC-coupled design optimized for
a detector with 50 m by 400 m pixels. The device has very low noise (60
electrons RMS) and high-speed readout, up to 840Mbits/s, including the
ability to interface to a level 1 type trigger. Each channel has 90 uW
power. Approximately 3000 FPIX2 chips have been produced in an
engineering run, with a high yield of fully functional devices. Test
results are very encouraging, with the prototypes demonstrating
excellent performance and minimal cross-talk. The FPIX2 and
specifications are shown in 2

![](media/image30.png){width="6.135416666666667in"
height="2.7395833333333335in"}

[]{#__RefHeading___Toc119116944 .anchor}Figure 26 - The FNAL FPIX2 pixel
readout chip

The electrical design of the FPIX2 chip is similar to that needed for
the Si Endcap pixels. The main change required is to adapt the physical
chip geometry to accommodate the Endcap sensors larger mini-strips.

Yarema has offered the services of his engineers and facilities to
perform this work. They have already completed a conceptual layout of
the modified PHX readout chip, which is shown in 9.

![](media/image31.png){width="2.1875in" height="2.7916666666666665in"}

[]{#__RefHeading___Toc119116945 .anchor}Figure 27 - Conceptual layout of
the PHX pixel readout chip. The left side graphic depicts the general
layout of the chip. Green is the area for bonding, blue the programming
interface, red the discriminator, orange the pipeline and yellow the
digital interface. The right side graphic shows the bonding layout, the
spacing is 200 micron. The signal and power bus will be routed on the
surface on the chip and bonded via the bump bonds on the ends of the
chip.

This elegant design has the readout bus structure integrated into the
chip itself, simplifying the sensor-readout assembly process. The PHX
chip will be bump-bonded to the sensor, with 200 m bump spacing. This
relatively large spacing was chosen to ensure high yields during the
assembly process. Yarema's team have also simulated the FPIX2 response
with input capacitances corresponding to our larger mini-strips and
found it to be acceptable. Design studies of the equivalent noise charge
of the FPIX2 cell with the expected capacitance of our ministrips has
already been done. The results are shown in With our capacitance
expected to extend to 1.5 pf we would expect an ENC of 300 electrons.
For a 200 um sensor this would correspond to a signal to noise of 50/1.
Optimization of the PHX chip could improve the signal/noise figure. The
PHX chips have LVDS outputs so they are able to drive the data up to 10
meters.

![](media/image32.png){width="5.373611111111111in"
height="4.083333333333333in"}

[]{#__RefHeading___Toc119116946 .anchor}Figure 28 - The equivalent noise
charge (ENC) verus capacitance.

## Silicon Mini-strip Sensors

We plan on using existing technology for the silicon sensor. Pixel
Sensor technology from the either the BTev effort will have the pixel
layout (masks) modified to match the longer mini-strips that we need.
The sensor technology needed for the modified PHX chip is the n^+^ on n
concept. The pixels consist of n^+^ - implantations in high resistivity
n type silicon while the pn-junction is located on the sensor's backside
surrounded by a multi guard ring structure. An advantage of this type of
sensor compared to the standard p^+^n -- sensors is that it can be
operated partially depleted if full depletion can not be reached anymore
due to radiation damage. Also, it keeps the side close to the pixel chip
to be held at ground potential thereby eliminating potentially
disruptive discharges between the sensor and chip. Developing the masks
for this effort will be done in concert with the vendors of the sensors.
Lengthy and costly R&D for the sensors is not necessary. The material
and electrical specifications for the BTev sensors are listed below.

**MATERIAL SPECIFICATION:**

Wafer diameter 4 inches (100mm**)**

Crystal orientation \<100\>

Thickness 250 m +10 m --20 m

Uniformity (across wafer) \< 10 m

Wafer bowing after processing \< 50 m (sagitta)

Doping of starting material: n-type

Resistivity: 1.5 -2.5 K cm

Uniformity of resistivity (wafer to wafer) 25%

> Oxygenation: the wafers need to undergo an oxygen thermal diffusion
> process for 24 hours at 1150C

Polishing: Double sided

Passivation: Covering both sides except for bond pads (both bump and
wire bond pads) and reference marks. It can either be silicon oxide or
silicon nitride.

**DESIGN PARAMETERS**

-   Devices shall be n^+^ pixels on n substrate using "moderated
    p-spray" as the n-isolation technology. Note: this is covered by a
    Non-Disclosure Agreement with six institutes in the ATLAS
    collaboration and three patents held by Garching Innovation.

-   The full design for the masks will be provided by us in electronic
    form (GDS-2 file)

-   Vendor will finalize the design details according to their design
    rules and process, and will work with us on the final design and
    mask layout. Any proposed change to the design must be approved by
    the BTeV pixel group.

-   Mask alignment precision within the same side : 2m

-   Mask Alignment precision between front and back side: 5m

-   Processing parameters shall be the same as for the ATLAS production
    moderated p-spray detectors (as covered by the Non-Disclosure
    Agreement and patents mentioned above):

> Front Side (n-side)

1.  N-implantation:

    -   minimum width 5 m

    -   minimum spacing 5 m

2.  P-implantation "moderated p-spray":

    -   minimum width 5 m

    -   minimum spacing 5 m

3.  Contact holes in oxide:

    -   minimum diameter 5 m

    -   minimum spacing 20 m

4.  Metal:

    -   minimum width 8 m

    -   minimum spacing 5 m

5.  Contact holes in passivation:

> \- Minimum diameter 12 m

-   minimum spacing 40 m

-   

Back Side (p-side):

1.  p-implantation:

    a.  minimum width 5 m

    b.  minimum spacing 5 m

2.  Contact via in oxide (or nitride):

    a.  minimum diameter 5 m

    b.  minimum spacing 10 m

3.  Metal:

    a.  minimum width 8 m

    b.  minimum spacing 5 m

4.  Contact via in passivation:

> \- Minimum width 50 m
>
> \- minimum spacing 100 m

Three different silicon sensors of trapezoidal shape are used to tile
the active areas of the Si Endcap, as shown in 0. Also shown is the
arrangement of the readout chips on each of the sensors. The largest
sensor is 79 mm high and 27 mm wide at its large end. Six PHX chips are
used to readout the 3072 mini-strips. The smaller sensors contain 2560
and 1536 strips.

The Si Endcap detector layers are assembled as shown in 1 through13.
First, the sensors are tiled on carbon panels that serve as the support
and cooling structure for each of the sector assembliesFigure 3011).
Next, 24 sectors are joined to form each of the four z-Statione 12).
Finally, the four z-Stations are assembled in each Si Endcap detectre
13). Each Endcap contains approximately.8975 million strips.

![](media/image33.png){width="5.010416666666667in" height="3.6875in"}

[]{#__RefHeading___Toc119116947 .anchor}Figure 29 - Three silicon
detectors will be used. The largest will have 6 chips reading out 3072
strips, the intermediate silicon will have 5 chips reading out 2560
strips and the smallest silicon is half the size of the largest with 3
chips reading out 1536 stri ps. (All dimensions are in millimeter)

![](media/image34.png){width="6.0in" height="3.4895833333333335in"}

[]{#__RefHeading___Toc119116948 .anchor}Figure 30 - A sector assembly
will have 24 carbon panels (one shown here in brown) in azimuth, each of
them carrying 4 silicon detectors (blue), two in the front and two in
the back. They overlap on the edges by a few millimeters to avoid dead
areas. The bus on a silicon assembly is routed on the chips as described
earlier, the connection of the inner silicon detectors is realized via a
kapton bus (golden).

![](media/image35.png){width="6.0in" height="3.3666666666666667in"}

[]{#__RefHeading___Toc119116949 .anchor}Figure 31. Each station carries
96 silicon detectors. The stations are placed at \~20, 26, 32 and 38 cm
from the interaction point.

![](media/image36.png){width="4.189583333333333in"
height="3.3305555555555557in"}

[]{#__RefHeading___Toc119116950 .anchor}Figure 32. Each endcap will have
4 stations of silicon detectors. The inner station has a reduced size in
order to not interfere with the HBD acceptance.

## Electronics Transition Module

The electronics transition module takes the continuously streaming data
from the PHX via flexible cables, bufferse the data for 64 beam clocks,
grabs the data from the appropriate beam clock upon a Lvl-1 trigger and
reformats the data before it is sent to the PHENIX DCMs. A data
buffering concept developed by Dr. C. Y. Chi, Columbia University, is
shown in Figure 33. The PHX data with the beam clock counter is routed
by an FPGA chip to one of 64 buffers corresponding to the beam clock
number. The FPGA than allows the data from the appropriate beam clock to
be sent to a level 1 trigger ( now in development by Iowa State
University) or to the DCM if a LV1 trigger accept is received. The
existing PHENIr DC's can be used without modification for this. The time
to pass all of the data to the LV1 trigger isi expected to bes \< 1 us.

![](media/image37.png){width="6.0in" height="3.84375in"}

[]{#__RefHeading___Toc119116951 .anchor}Figure 33 - The transition
module concept

The buffering requirements of the transition module are expected to be
quite modest with \<50 kbits of data expected in Central AuAu events for
up to 44 chips ganged together. Noise hits are expected to take even
less space. The readout time is expected to be kept below 4 beam clocks
for Central AuAu events as we will likely be employing more than one
readout line per chip. Some calculations of data sizes and readout times
can be found in for various options of readout lines, chip ganging, and
assuming readout speed is synced to give an integral number of beam
clocks needed per data word.

  -------- --------------- -------- ----------- ----------- -------- --------- ------- -------- -------- --------- --------- --------- ----------- ---------
  Layers   channels/chip   chips/   channels/   Occupancy   Real     Real data Noise   Clocks   Noise    Noise     Buffer    Number of Readout     Readout
  Ganged                   board    board                   Hits/ 64 size/64                    Hits/ 64 data      needed    Readout   Time/data   Latency
                                                            Clocks   clocks                     Clocks   size/64   for 64    Lines     word (nsec) (beam
                                                                     (kbits)                             clocks    clocks                          clocks)
                                                                                                         (kbits)   (kbits)                         

  1        512             11       5632        0.015       84.48    2.03      0.001   64       360.4    8.7       10.7      1         212.4       17.4

  4        512             44       22528       0.015       337.92   8.11      0.001   64       1441.8   34.6      42.7      1         212.4       17.4

  1        512             11       5632        0.015       84.48    2.03      0.001   64       360.4    8.7       10.7      2         106.2       8.7

  4        512             44       22528       0.015       337.92   8.11      0.001   64       1441.8   34.6      42.7      2         106.2       8.7

  1        512             11       5632        0.015       84.48    2.03      0.001   64       360.4    8.7       10.7      4         35.3        2.9

  4        512             44       22528       0.015       337.92   8.11      0.001   64       1441.8   34.6      42.7      4         35.3        2.9

  1        512             11       5632        0.015       84.48    2.03      0.001   64       360.4    8.7       10.7      6         35.4        2.9

  4        512             44       22528       0.015       337.92   8.11      0.001   64       1441.8   34.6      42.7      6         35.4        2.9
  -------- --------------- -------- ----------- ----------- -------- --------- ------- -------- -------- --------- --------- --------- ----------- ---------

Table 4 Buffer requirements for the transition module for AuAu events,
various options of readout lines/chip, different levels of chip ganging,
and a very conservative noise estimate. Also, the time to readout an
event is given for the same conditions.

## Mechanical Structure and Cooling

The mechanical structures and cooling are part of the integrated design
of the barrel and endcaps. The majority of the support structure will be
designed as part of the barrel effort and remaining issues concerning
ladders and cooling specific to the endcaps will be part of this
proposal.

A conceptual design of the silicon vertex detector was commissioned by
the LANL group

to HYTEC, Inc. HYTEC is the mechanical designers for the ATLAS silicon
pixel group and has 15 years of design experience with silicon vertex
detectors. For PHENIX they have also designed the station-1 muon
detectors and the station-2 spider and also did the finite element
analysis of the station-3 octants. The VTX mechanical conceptual design
was finished and the report written. Recently in September 2005 the
original concept was reanalyzed to incorporate changes that have
occurred over the past 2 ½ years. A report was issued in October 2005.
We will summarize the results of both reports

For the internal support and cooling of the VTX detector, the major
results of the

conceptual design are:

> • The use of sandwich composites will satisfy the radiation length
> requirements and
>
> provide the required stiffness.
>
> • The outer frame structure should be a single diameter encompassing
> both the
>
> barrel and end-caps.
>
> • The modular clamshell design can satisfy the stability requirements
> provided the
>
> connection issues are studied further.
>
> • An octagon arrangement is suggested to facilitate utility routing
> and fabrication.
>
> • Structural end disks at either end of the structure are recommended
> to prevent
>
> deformation
>
> • The ladders should have a simple support at one end and floating
> support at the
>
> other end to minimize thermal strains

The R&D issues identified are:

> • Building prototypes of ladder assemblies to verify calculations.
>
> • Building full-scale prototype to test static and dynamic stiffness.
>
> • Develop connections of modules.
>
> • Develop support design.
>
> • Refine calculations and develop full concept for 0 deg operation.
>
> Design Criteria

The goal of the study is to establish a feasible design and to identify
outstanding design

issues. The study is based on a preliminary list of design requirements
and a straw-man

layout of the detector structure. To adequately address all structural
and mounting issues

a fully integrated design, which includes the barrel detectors and
future end-caps

extension, is needed. This design needs to address all integration
issues not only for the

barrel and the end-cap vertex trackers, but also with other potential
PHENIX upgrades.

The design requirements of the conceptual study were,

> • Modular Design
>
> o End-caps detectors can be mounted independently at a later time
>
> o Support structure separated vertically into two half shells
>
> • Detector Coverage
>
> o Hermetic design
>
> o Four barrel layers
>
> o Four end-cap layers in each forward section
>
> o Fiducial volume \< 20 cm radius, z \< 40cm
>
> • Radiation length goal \< 1% per layer
>
> • Room temperature operation desirable, 0 deg Celsius if needed
>
> • Dimensional stability \< 25 microns

Structural Support

The selection of materials for the support structure is based upon the
above criteria where

the most important material properties are high radiation length, low
density, high

stiffness, and availability. Out of three candidates (i) beryllium, (ii)
graphite fiber

reinforced plastic (GFRP), and (iii) Carbon-Carbon, the GFRP was chosen
for the study

because of its wide availability, works well in sandwich composites, and
has good

radiation length and strength properties. The GFRP is still the material
of choice.

The Enclosure and Environmental Envelope

The original conceptual design was for room temperature operation.
Because of the requirement for 0 deg operation, we now need to include
an environmental enclosure. Shown in figure XXX is an isometric view of
this new design. The original concept was for an octagonal structural
enclosure uniform in outside radius and this is retained. Added is the
new environmental enclosure to contain the dry gas.

![](media/image38.wmf){width="2.6in" height="2.734027777777778in"}

![](media/image39.wmf){width="2.23125in" height="2.622916666666667in"}

[]{#__RefHeading___Toc119116952 .anchor}Figure 34 - An isometric view of
the VTX showing all of the internal features coaxial with the beam tube,
namely (moving out from the beam tube), two cylinders of pixel
detectors, two cylinders of strip detectors, the GRFP structure (gray in
color), and finally, the cylindrical enclosure wall.

### Endcap Ladder Structure

The forward regions consist of 4 conical arrays of ladder modules tilted
from the normal to the beam pipe by 22 deg. Conceptually, we have chosen
a flat octagonal panel structure with sensors and electronics mounted on
either side of the panel so that we can achieve hermetic coverage.
Figure 35 shows this arrangement on the left and an octagon panel
structure onht.

![](media/image40.jpeg){width="2.501388888888889in"
height="2.220833333333333in"}

[]{#__RefHeading___Toc119116953 .anchor}Figure 35 - 3D model of
octagonal disk like structures for the endcap ministrips. Cooling tubes
are to demonstrate both the number and routing.

![](media/image41.jpeg){width="2.2118055555555554in"
height="2.7527777777777778in"}

[]{#__RefHeading___Toc119116954 .anchor}Figure 36 - The octagon panel
structure is on the right with the cooling channel shown. A heat load of
0.1 W/cm\*\*2 is assumed.

The original concept was designed for a modified LHCb chip with a total
heat load on each endcap of approximately 450 W, or about 15W per octant
panel. The new PHX chip has a heat load of 90 uW per channel so the
total for each end cap now is \~70 W or 2.2 W per octant panel. This
much lower number indicates that convective cooling might be possible.
In comparison to the barrel this is a very small heat load and greatly
simplifies the removal of the waste heat. The octant panel structure
consists of a composite sandwich of C_C facings on either side of a
carbon foam in which is embedded an aluminum cooling tube(5). Thermal
and gravity sag calculations were performed in a manner similar to those
discussed in chapter 4 and no serious distortions were observed. For the
case of 0 deg operation, more work is necessary.

![](media/image42.png){width="3.9319444444444445in"
height="2.2104166666666667in"}

[]{#__RefHeading___Toc119116955 .anchor}Figure 37. Illustration of an
embedded cooling passage arrangement in the composite sandwich used in
the endcap thermal and static calculations. The upper panel depicts a
circular tube with supports and the bottom panel shows a flattened tube
which enhances heat transfer and provides a thinner sandwich.

### Radiation Length

The thermal and static design studies produced a range of solutions for
the endcaps 6 shows the radiation length estimate for different cooling
tube dimensions. The parameters used in the calculations are:

-   Al tube, 200 micron.

-   4 mm carbon foam separator.

-   Tube support 2 mm wider than tube diameter.

-   Sandwich facings of 400 micron.

![](media/image43.png){width="3.9972222222222222in"
height="2.1840277777777777in"}

[]{#__RefHeading___Toc119116956 .anchor}Figure 38. Estimated normal
radiation length for the endcap octant panel for different tube
diameters.

## Endcap Analysis Summary

## 

## 

######## The conceptual design studies revealed the following: {#the-conceptual-design-studies-revealed-the-following .unnumbered}

######## Single phase cooling is well suited to the endcaps.

-   Two adjacent octant panels can be cooled in series thus reducing
    service connections.

-   2mm cooling tubes and panel thickness are adequate.

-   The radiation length of the octant panel exclusive of sensor and
    electronics is \~ 0.6 %.

The R&D issues consist of refining the calculations, designing
attachment points to the main support structure, and prototyping the
octant panels.

# R+D Schedule, Responsibilities and Budget

The R&D associated with the endcap involve modifying the topology of the
PHX chip, developing the interface between the PHX chip and the existing
PHENIX DCMs, modifying the design of an existing sensor, developing the
stave structure, and developing the bus and flex cable. The interface is
the most involved of the R&D projects. The rest are starting from
existing technology or use standard commercial concepts. The R&D for the
endcaps will be supported in two places, LANL and BNL. At LANL we will
complete the R&D for the interface, the mechanical support and ladder,
and the sensor design. BNL will support the R&D for the PHX design and
modification. All activities will begin in FY2006.

PHX

The PHX chip is a modification of the FPIX2 pixel chip used for the BTev
experiment. The modifications take it from a 22 column x 128 channel
structure to a 2 column x 256 channel structure. The R&D issues involve
optimizing the frontend for the mini-strips, designing the built in bus
structure and incorporating the redesign of the digital section to be
identical to that in the FSSR chip. The digital section redesign has
already been done for the FSSR and tested successfully. The most
difficult of these R&D issues is the integral bus and will be designed
first.

SENSOR

The sensor will be identical technology that is used in the BTev sensor
design which is the same as that used in the ATLAS pixel design. We have
obtained the design specifications for this sensor. We will produce new
drawings for the 2 column ministrip layout. The significant R&D will be
to design into the sensor the small bus extension for the daisy chain
from one chip to another.

INTERFACE

The interface board that will reside between the PHX chip and PHENIX
DCMs will need to provide the following functions:

-   Provide buffering of the continuously streaming data from the PHX
    chips for 64 beam clocks, and this buffering must be adequate for
    everything from pp running to AuAu running

-   Upon a lvl-1 accept, retrieve the data from the buffer for the
    appropriate beam clock and package it into a format acceptable by
    the DCM

-   Pass beam clock to the PHX chip

-   Perhaps keep track of BUSY state of chip to make sure that data for
    a given lvl-1 is really available

-   Provide an interface to download initialization settings to the PHX
    chips

-   Perhaps provide ability to reset PHX chip(s)

We expect the board design to be not too much different from a number of
other PHENIX interface boards, containing an FPGA to handle the data
buffering and packaging and I/O lines to PHENIX T+FC, DCM, ARCnet (or
equivalent) and to the PHX chip readout lines. The FPGA code development
we expect to take several months, as has been standard for PHENIX, so we
are hoping that we can begin development on the code even in the absence
of the final PHENIX interface board as we already have some FPGA boards
which can nominally provide all the I/O lines needed to develop the code
that has the above functions. We are currently discussing what
combination of LANL, Columbia,... institutions will work on this portion
of the project.

## Schedule

The R+D schedule for project 2 is shown below. Also shown is a
construction and installation schedule assuming funds are available now.
This will slide with funds availablity. The R+D is expected to begin in
early FY05 and be completed by late FY06.

### 

![](media/image45.png){width="5.9944444444444445in"
height="3.990972222222222in"}

![](media/image46.png){width="5.9944444444444445in"
height="2.4097222222222223in"}

Figure 40 - PHENIX Forward Silicon Vertex (FTV) project timeline.

###  Cost

Since the FVTX will be added to the existing barrel vertex detector,
VTX, much of the needed infrastructure, cooling, enclosure, cable
routing, installation procedures, etc will already have been done and
are in place. In this cost estimate only those items needed for the
fitting the FVTX into the VTX enclosure are considered. The cost basis
is generally gotten from cost estimates by the engineering team who will
be doing the work and by cost estimates for work done by those teams.
For example, the cost estimate for the PHX chip came from the FNAL
engineers who designed the FPIX2 chip. The HYTEC engineering team
previously designed the ATLAS pixel mechanical structures and that forms
the basis for the mechanical cost estimates.

  ------------------------ ---------- ----------- ------------------- ----------------------
  Forward Endcap Cost                                                 
  Estimate - FVTX                                                     

  2 endcaps                R&D        R&D         Construction(k\$)   comments
                           BNL(k\$)   LANL(k\$)                       

                                                                      

  Mechanical ladder and    10         50          160                 HYTEC Estimate
  support structure                                                   

  Silicon Sensor,tested               50          530                 Includes 50k for
                                                                      testing

  PHX chip, tested         440                    355                 Includes 60k for
                                                                      testing, FNAL Estimate

  Inteface - phx to DCM,              200         403                 
  CHI concept                                                         

  bump bond chip to sensor                        414                 Btev experience

  Assembly and test                               200                 
  ladders                                                             

  Electronics Integration                         250                 Engineer

  Mechanical Integration                          250                 Engineer

  power supplies                                  100                 

  bus                      20                     160                 flex cables

  cables                                          160                 flex cables

  total                    470        300         2982                
  ------------------------ ---------- ----------- ------------------- ----------------------

### Project Management and Responsibilities

The LANL Group will work together with HYTEC inc. to develop the design
for the Endcap mechanical ladder and cooling. LANL has formed
collaboration with FNAL to design, prototype and test the PHX readout
chip. An MOU with PHENIX, BNL physics department and FNAL for R&D of the
PHX chip was signed in 2004.

Overall systems integration and management -- LANL

Mechanical Engineer -- Walt Sondheim

Electrical Engineer --

Sensors -- Charles University

PHX development -- FNAL, LANL,...

Interface -- Columbia University, LANL

Flex cables and bus --

Assembly and testing -- University of New Mexico

Simulation effort (?) \[insertion by MB\]

Institutional Responsibilities

Los Alamos National Laboratory

Los Alamos is currently leading the mechanical engineering and the
integration effort for the barrel detector, VTX. and will continue those
efforts for the FVTX. They will also work with FNAL on the development
of the PHX chip and with Columbia on development of the interface to
PHENIX DAQ, and on the simulation effort with NMSU.

Columbia University

Columbia University is an acknowledged expert on the PHENIX DAQ system
They will work on the interface between the PHX chip and the PHENIX DAQ.

Iowa State University

Iowa State University is currently working on management details with
the barrel detector and working on an SBIR effort for the

Charles University, Prague

Charles University has been active in the development, testing,
assembly, and commissioning of the ATLAS pixel sensors. They will do the
same for the FVTX effort. They will also participate in software
development.

New Mexico State University

NMSU will work on the simulations for the FVTX effort.

University of New Mexico

UNM has experience in testing, Q/A and a laboratory for characterization
of sensors. They are currently working on the barrel strip sensors and
will do the same for the FVTX effort.

Ecole Polytechnique

Argonne National Laboratory ?

More

Appendix A

### Contingency Analysis

The average contingency for the FVTX is 30 %.

This section describes how the contingency for a given WBS element was
calculated.  Risk is a function of the following factors:  the
sophistication of the technology, the maturity of the design effort, the
accuracy of the cost sources and the impact of delays in the schedule. 
Risk analysis is performed for each WBS element at the lowest level
estimated.  Results of this analysis are related to a contingency which
is listed for each WBS element.  The goal is to make the method of
contingency determination uniform for all project WBS elements.

> **Definitions**
>
> **Base Cost Estimate** -- The estimated cost of doing things correctly
> the first time. Contingency is not included in the base cost.
>
> **Cost Contingency** -- The amount of money, above and beyond the base
> cost, that is required to ensure the project\'s success. This money is
> used only for omissions and unexpected difficulties that may arise. 
> Contingency funds are held by the Project Manager.
>
> **Risk Factors**
>
> **Technical Risk** -- Based on the technical content or technology
> required to complete the element, the technical risk indicates how
> common the technology is that is required to accomplish the task or
> fabricate the component.  If the technology is so common that the
> element can be bought \"off-the-shelf\", i.e., there are several
> vendors that stock and sell the item, it has very low technical risk,
> therefore a risk factor of 1 is appropriate.  On the opposite end of
> the scale are elements that extend the current \"state-of-the-art\" in
> this technology.  These are elements that carry technical risk factors
> of 10 or 15.  Between these are: making modifications to existing
> designs (risk factor 2-3), creating a new design which does not
> require state-of-the-art technology (risk factor 4 & 6), and creating
> a design which requires R&D, and advances the state-of-the-art
> slightly (risk factor 8 & 10).
>
> **Cost Risk** -- Cost risk is based on the data available at the time
> of the cost estimate.  It is subdivided into 4 categories.
>
> The first category is for elements for which there is a recent price
> quote from a vendor or a recent catalog price. If the price of the
> complete element, or the sum of its parts, can be found in a catalog,
> the appropriate risk factor to be applied is 1. If there is an
> engineering drawing or specification for the element, and a reliable
> vendor has recently quoted a price based on these, the cost risk
> factor to be applied is 2. Similarly, if a vendor has quoted a price
> based on a sketch that represents the element, and the element\'s
> design will not change prior to its fabrication, the appropriate cost
> risk factor would be 3.
>
> The second category is for elements for which there exists some
> relevant experience.  If the element is similar to something done
> previously with a known cost, the cost risk factor is 4.  If the
> element is something for which there is no recent experience, but the
> capability exists, the cost risk is 6.  If the element is not
> necessarily similar to something done before, and is not similar to
> in-house capabilities, but is something that can be comfortably
> estimated, the risk factor is 8.
>
> The third category is for elements for which there is information
> that, when scaled, can give insight into the cost of an element or
> series of elements.  The cost risk factor for this category is 10. 
>
> The fourth category is for elements for which there is an educated
> guess, using the judgment of engineers or physicists.  If there is
> experience of a similar nature, but not necessarily designing,
> fabricating or installing another device, and the labor type and
> quantity necessary to perform this function can be estimated
> comfortably, a cost risk factor of 15 is appropriate.
>
> **Schedule Risk** -- If a delay in the completion of the element could
> lead to a delay in a critical path or near critical path component,
> the schedule risk is 8.  If a delay in the completion of the element
> could cause a schedule slip in a subsystem which is not on the
> critical path, the schedule risk is 4.  Only elements where a delay in
> their completion would not affect the completion of any other item
> have schedule risks of 2.
>
> **Design Risk** -- is directly related to the maturity of the design
> effort. When the element design is nearly complete, quantity counts
> and parts lists finished, the risk associated with design is nearly
> zero; therefore a risk factor of 0 is applied.  This is also the case
> when the element is an \"off-the-shelf\" item and the parts counts and
> quantities are finalized.  When the element is still just an idea or
> concept, with crude sketches the only justification for the cost
> estimate, the risk associated with design state is high or 15. 
> Between these two extremes are the stages of conceptual design and
> preliminary design.  In conceptual design, when layout drawings of the
> entire element are approaching completion, some preliminary scoping
> analyses have been completed, and parts counts are preliminary, the
> design risk factor is 8.  During preliminary design, when there are
> complete layout drawings, some details worked out, complete parts
> counts, and some analysis for sizing and showing design feasibility,
> the appropriate design risk is 4.
>
> **Weighting Factors**
>
> The weight applied to the risk factors depends on whether there are
> multiple or single risks involved in completing an element. 
>
> The weights applied to technical risk depend upon whether the element
> requires pushing the current state-of-the-art in design,
> manufacturing, or both.  If the element requires pushing both, the
> weight to be applied is high, or 4; if either the design or
> manufacturing are commonplace, the weighting factor is 2.
>
> For weights applied to cost risk, the two factors are material costs
> and labor costs.  If either of these are in doubt, but not both, the
> weight to be applied to cost risk is 1.  If they are both in doubt,
> the weight applied is 2.
>
> The weight factor given to schedule risk is always 1.
>
> The weight factor given to design risk is always 1 and so is not shown
> explicitly.
>
> ** Procedure**
>
> The following procedure is used for estimating contingency.
>
> **Step 1** **--** The conceptual state of the element is compared with
> Table 4 to determine risk factors.  A technical risk factor is
> assigned based on the technology level of the design.  A design risk
> factor is assigned based upon the current state (maturity) of the
> design.  A cost risk factor is assigned based on the estimating
> methodology used to arrive at a cost estimate for that element. 
> Similarly, a schedule risk factor is identified based on that
> element\'s criticality to the overall schedule.
>
> **Step 2** **--** The potential risk within an element is compared
> with Table 5 to determine the appropriate weighting factors. 
>
> **Step 3** **--** The individual risk factors are multiplied by the
> appropriate weighting factors and then summed to determine the
> composite contingency percentage.
>
> **Step 4** **--** This calculation is performed for each element at
> its lowest level.
>
> **Step 5** **--** The dollar amount of contingency for an element is
> calculated by multiplying the base cost by the composite contingency
> percentage.

Table 4: Technical, cost, and schedule risk factors.

  ---------- ------------------ ------------------ -------------- ---------------
  **Risk     **Technical**      **Cost**           **Schedule**   **Design**
  Factor**                                                        

  0          Not used           Not used           Not used       Detail design\
                                                                  \> 50% done

  1          Existing design    Off-the-shelf or   Not used       Not used
             and\               catalog item                      
             off-the-shelf H/W                                    

  2          Minor              Vendor quote from  No schedule    Not used
             modifications to   established        impact on any  
             an existing design drawings           other item     

  3          Extensive          Vendor quote with  Not used       Not used
             modifications to   some design                       
             an existing design sketches                          

  4          New design;\       In-house estimate  Delays         Preliminary
             nothing exotic     based on previous  completion of  design \>50%
                                similar experience non-critical   done; some
                                                   subsystem item analysis done

  6          New design;        In-house estimate  Not used       Not used
             different from     for item with                     
             established        minimal experience                
             designs or         but related to                    
             existing           existing                          
             technology         capabilities                      

  8          New design;        In-house estimate  Delays         Conceptual
             requires some R&D  for item with      completion of  design phase;
             but does not       minimal experience critical path  some drawings;
             advance the\       and minimal        subsystem item many sketches
             state-of-the-art   in-house                          
                                capability                        

  10         New design of new  Top-down estimate  Not used       Not used
             technology;        from analogous                    
             advances           programs                          
             state-of-the-art                                     

  15         New design; well   Engineering        Not used       Concept only
             beyond current\    judgment                          
             state-of-the-art                                     
  ---------- ------------------ ------------------ -------------- ---------------

Table 5: Technical, cost, schedule, and design weighting factors.

  --------------- ---------------------------------------- ------------------
  **Risk Factor** **Condition**                            **Weighting
                                                           Factor**

  **Technical**   Design OR Manufacturing                  2

                  Design AND Manufacturing                 4

  **Cost**        Material Cost OR Labor Rate              1

                  Material Cost AND Labor Rate             2

  **Schedule**    Same for all                             1

  **Design**      Same for all                             1
  --------------- ---------------------------------------- ------------------

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