Report of the RHIC Planning Group

Draft 3 11/19/03

Text in blue was added 11/24/03 T.L.

Text in red was added 11/25/03

# Overview

The RHIC Planning group was convened in August 2003 as a means of
engaging the broad community of RHIC users, accelerator groups, and BNL
management in a focused effort to map the core scientific priorities of
the RHIC community onto a realistic schedule for facility operations and
upgrades. The membership of the group is shown in App. 1. It consisted
of representatives from each of the experimental collaborations, the
RHIC machine groups, the RHIC Computing Facility, the BNL nuclear theory
group, and the principal scientific advisory committees.

The group carried out its work through a series of bi-weekly discussion
meetings held during the months of Sept. -- Nov. 2003. The planning
activity has been approached in two phases:

1.  A five-year operations plan (through 2008). The discussion here has
    focused on how to satisfy the baseline RHIC physics program, and set
    the stage for the long-term scientific goals, in the context of a
    "constant effort" budget scenario as indicated by DOE guidance for
    near-term operations and research budgets. Our analysis shows that,
    even after optimizing the flexibility of operations by combining
    runs across fiscal years, such a scenario is not adequate for
    realizing the main goals of the RHIC Heavy Ion and Spin programs.
    Thus we also consider an incremental improvement of the constant
    effort scenario in an attempt to satisfy minimal running
    requirements for the period 2004 - 2008.

2.  A mid- to long-term outlook (out to 20 years). The goal here is to
    establish the most important scientific issues that drive the need
    for future upgrades of the machine and detectors; to evaluate the
    scope, cost and timescale of the RHIC II upgrade; and to assess the
    sequence of activities that need to take place in the scientific
    community, and at the level of BNL and DOE management, to realize
    both the RHIC II and eRHIC projects.

The purpose of this planning group was not to start from scratch to
develop a long-term plan for the RHIC facility, but to follow up on, and
integrate, the ongoing work of planning activities such as the
following:

-   The Beam Use Requests and Decadal Plans developed by the
    experimental collaborations

-   Recommendations of BNL's HENP Program Advisory Committee and RHIC
    Detector Advisory Committee

-   Requirements developed by the C-A Dept. for continued improvement of
    machine performance

-   DOE budget guidance

-   The NSAC Long Range Planning process

I.  **Five-year run planning (2004 -- 2008)**

> The critical goals in this period are:

a.  To follow up on the watershed results of the first RHIC runs by
    making definitive experimental statements on the existence of the
    quark gluon plasma and determining its essential properties.

b.  To get spin-polarized p-p data samples of sufficient sensitivity to
    address the core physics questions of the RHIC spin program,
    including direct determination of the spin-dependent gluon structure
    functions.

Each of the experimental collaborations provided its own view of this
planning through the Beam Use Proposals submitted in August, and
presented to the PAC in September. They were asked to consider two
cases: A "constant-effort" funding scenario (based on the FY 2004
presidential budget), which was assumed to correspond to 27 weeks of
cryogenic operations per year, and a scenario corresponding to 37 weeks
of operation annually, as was initially proposed for RHIC.

The key guidance for determining the scientific productivity of a
particular running scenario is given by the document "RHIC Collider
Projections (FY 2004 -- FY 2008)", by T. Roser and W. Fischer. In broad
outline, this gives the following constraints on the utilization of the
facility during a single cryogrenic run:

1.  Cool-down and warm-up require a total of 3 weeks.

2.  Each mode of running requires 2 weeks of set-up and 3 weeks of
    ramp-up to stable physics operation. (A change in energy, after
    stable operation is achieved with a given set of species, requires
    only 2 weeks.)

3.  Both minimum and maximum luminosity projections are given. The
    minimum values assume little improvement over presently-established
    performance. The maximum values assume steady improvement in
    performance, requiring long periods of sustained running in a given
    mode. In this planning model the weekly luminosity increases
    linearly in time, reaching the target value only after 14 weeks of
    production running .

From the detailed Beam Use Proposals -- particularly those of STAR and
PHENIX -- it is evident that achieving the two critical goals listed
above, in a timely manner, is a severe challenge in light of the
constraints on beam availability imposed by the need to run in many
modes, and the need for machine development to reach necessary levels of
performance.

The design target for full utilization of the RHIC facility calls for a
37 week/year operations schedule. To date, the amount of running has
been determined by the RHIC operations budget. With the present guidance
from DOE, this budget is expected to remain relatively flat at the level
of FY 2004. This "Constant Effort" budget scenario is estimated to
support 27 weeks per year of running.

While the Beam Use Proposals address both the full-utilization scenario
and the Constant Effort case, this Planning Group has focused on the
latter. ~~Clear~~ Current guidance from DOE on future budget levels
requires us to consider this case as the more likely. Furthermore, this
case presents severe challenges that will require the most careful
planning as well as difficult compromises.

From the presentations in the Beam Use Proposals one can outline a
minimal set of physics runs and data samples to achieve the critical
goals listed above. We show this minimal set in Table 1.

+--------------+-------------------------------------------------------+
| Heavy Ions   |                                                       |
+--------------+-------------------------------------------------------+
| 1\.          | A "long" 200 GeV Au Au run (\>300 μb^-1^) in 2004 to  |
|              | follow up on high p~T~ results, and get the first     |
|              | sizeable sample of J/ψ.                               |
+--------------+-------------------------------------------------------+
| 2\.          | An energy scan:                                       |
|              |                                                       |
|              | Au Au at 1 or 2 lower energies. 50-100 μb^-1^ total   |
+--------------+-------------------------------------------------------+
| 3\.          | Species scan:                                         |
|              |                                                       |
|              | 1 -- 2 lighter ions at 200 GeV. 3-6 nb^-1^ total      |
+--------------+-------------------------------------------------------+
| 4\.          | High-statistics Au Au run at 200 GeV in 2007 or 2008, |
|              | with upgraded detector capability for open charm and  |
|              | particle i.d. at high p~T~ (≥3000 μb^-1^)             |
+--------------+-------------------------------------------------------+
| Spin         |                                                       |
+--------------+-------------------------------------------------------+
| 1\.          | 15-20 weeks of "development" in 2004 -- 2005 (this    |
|              | would include some physics data, but is required      |
|              | primarily to get the luminosity and polarization up   |
|              | to required levels).                                  |
+--------------+-------------------------------------------------------+
| 2\.          | Full-capability spin data at 200 GeV. ≥300 pb^-1^     |
+--------------+-------------------------------------------------------+

## Table 1. Minimal running requirements for the period 2004 -- 2008

*Note that the sample sizes indicated here are for
[delivered]{.underline} integrated data rates.*

It must be noted that Table 1 omits several measurements that are
strongly advocated by the experimental community. Omitted from this
table are a second, long deuteron-Au run (an omission of perhaps
questionable wisdom in light of the excitement generated by the recent
BRAHMS results on forward hadron suppression in d-Au data), any
significant start on 500 GeV pp running (and, therefore, on W
production), and runs of sufficient length with lower energy Au-Au
collisions and lighter ion species to study rare probes.

Table 2 shows a thumb-nail summary of the Beam Use requests from the
four experiments in the case of 27 weeks per year of cryogenic running.
Note that Table 2 shows the proposed [recorded]{.underline} data samples
for PHENIX, as well as the corresponding requirement for the delivered
luminosity.

(Table 2 appears as an attachment at the end of this document.)

Table 2 is the result of a lengthy and intense effort by the
experimental collaborations to make scientific choices and impose
programmatic discipline and efficiencies to achieve the most physics
possible with 27 running weeks per year. ~~While a program based on the
proposals shown in Table 2 appears to come close to meeting the minimal
requirements of Table 1, in fact it does so only by accepting the most
optimistic projections for machine and detector performance. (The PHENIX
projections for integrated proton-proton luminosity exceed the
guidelines given by C-A.)~~ Nonetheless, it does not seem possible, even
under optimistic projections for machine and detector performance, to
reach all of the requirements in Table 1 within a 5-year, 27-week/year
plan. (The PHENIX projections for integrated proton-proton luminosity in
Table 2 considerably exceed the C-A guidelines.) A clear conclusion,
articulated strongly in both the PHENIX and STAR Beam Use proposals, is
that a running plan providing only 27 weeks per year does not satisfy
the minimum requirements of the scientific program. This is not simply
an incremental matter that can be resolved by allowing another year or
so of running. It is a fundamental problem that arises from the fact
that the overall program requires large data samples under many
different running conditions, with relatively long set-up times for each
change in running conditions, combined with the need for long sustained
runs to achieve necessary improvements in machine performance.

We have considered ways of improving the utilization of the facility
under a constant-effort budget constraint by allowing runs to be
combined across fiscal years to improve the flexibility for long runs,
while reducing the number of warm-up/cool-down cycles over the five-year
period. We examined the following three schemes, each of which assumes
that the FY 2004 run proceeds as scheduled:

[Scheme 1:]{.underline} The four runs in FY 2005 -- FY 2008 are combined
to provide two 54-week runs, interspersed with 50-week shutdowns.

[Scheme 2:]{.underline} (Proposed by STAR) The four runs in FY 2005 --
FY 2008 are combined to provide three runs of 35 to 37 weeks each, with
correspondingly shorter shut-down periods.

[Scheme 3:]{.underline} (Proposed by PHENIX) Relatively short runs
dedicated to spin running and development are interspersed with longer
runs for heavy ions.

These schemes are illustrated in Fig. 1.

![](media/image1.wmf)

Fig. 1. Alternate schemes for Constant-Effort run plans. The "standard"
27 weeks/yr plan is shown at the bottom.

These ideas led to a discussion of whether it is practical to consider
running the facility during the hot summer months. Derek Lowenstein
pointed out that there is no strict prohibition from the point of view
of power costs or restrictions by our electrical suppliers. After some
consideration, Thomas Roser and Phil Pile concluded that the cooling
capacity in certain support buildings and detector areas would require
some improvement, but that there are no compelling reasons not to
consider Schemes 1 and 2 on this basis.

Schemes 1 and 2 each provide a long shut-down period after the 2004 run,
which could be beneficial for installing equipment essential for the
anticipated spin run in 2005, such as the AGS strong snake, NEG coated
vacuum pipes in RHIC, and the STAR EM Calorimeter. There is general
agreement that the extreme case represented by Scheme 1 would be
detrimental to the completion of the PHOBOS and BRAHMS experiments, and
is not well aligned with the anticipated schedule of upgrades for STAR
and PHENIX.

Schemes 2 or 3, or some further variant, could provide an additional 3-6
weeks of physics running over the five-year period. The added ability to
carry out long runs in the modes listed in Table 1 is real, but
certainly not decisive.

From these exercises, one can reach the following conclusions:

-   27 weeks is an awkward number: if one tries to run 2 species/yr, it
    leaves only 14 weeks for physics production/year, and introduces
    significant luminosity limitations. The alternative scenarios above
    are aimed at finding more efficient ways of handling overhead.

-   The timing and duration of shutdowns has important influence on the
    staging of both spin and heavy-ion measurements.

-   In addition to integrated running weeks, the efficiency of getting
    to major spin physics goals depends on the frequency, duration, and
    timing of pp runs and of equipment installation needed to overcome
    present limits on both luminosity and polarization.

-   All of the constant-effort scenarios considered above preserve the
    average of 27 weeks per year. Schemes that add flexibility in
    planning do have value, and should be considered, but do not solve
    the fundamental problems for achieving the near-term physics goals.

In light of this last point, the group considered an incrementally
improved operating scenario over the five-year period, in order to meet
the requirements in Table 1. While it is impossible to make a
hard-and-fast statement, an examination of Table 1, and of the Beam Use
proposals, shows that an increment on the order of 5 weeks per year over
the 5-year period could make a qualitative improvement in the physics
output. This would allow (for example) one "long" run of ~~5+14~~ 19
weeks during each year (including setup time), plus one short, but still
meaningful run of 10 weeks (again including setup time).

In order to assess the budgetary impact of such an improved scenario, we
have compiled the projected facility operations costs shown in Table 3.

Table 3 appears as an attachment at the end of this document.

The table shows the actual operations costs in FY 2003, and the
projected costs for running 27 weeks through FY 2008. Also shown are the
estimated incremental costs for additional weeks of running.

One thing to note about this table is that it does not quite satisfy a
constant-effort scenario (flat budgets except for inflation). Some
savings must be found in order to meet the constant-effort requirement,
even at the level of 27 weeks/year. ~~This is a work in progress.~~ BNL
is committed to finding a solution to this critical issue. (Another
note: The "research equipment" lines refer to on-going and proposed
upgrades to the detectors and machine, as discussed in Sec. III below.
These are not part of the operations budget for the facility, and are
regarded by DOE as competitive across the NP program. We do not include
these under the constant-effort constraint.)

From Table 3, the estimated incremental cost of adding additional
running weeks to a base of 27 weeks is \$437K/week in FY 2004. (This
number increases to \$452K/wk in FY 2005 because of additional costs of
recording media for PHENIX, and it increases to \$602K/wk in FY 2006
because of anticipated increases in power cost.) This number also
represents the savings incurred if RHIC were to run fewer than 27
weeks/year. The C-A Dept. has stated that if the number of added weeks
is more than "a few" these costs will be larger because additional
manpower will be required. The total cost of adding five more weeks is
estimated to be \~\$4M. This would be an increase of about 3% in the
operating budget for RHIC.

In summary, a number of-constant effort scenarios have been considered,
all of which preserve an average of 27 cryogenic running weeks per year,
with redistributions among years possible. These scenarios are
budget-driven, not science-driven. The Planning Group concludes that in
order to successfully carry out the heavy-ion and spin programs, BNL
must aim for annual running periods of 32 weeks or more. With current
projections of the RHIC operating budget, the Laboratory has to strain
to reach even 27 weeks. To average 32 weeks per year will require
additional funds (an increment of \~3% of the operations total).

[Priorities:]{.underline}

-   As illustrated in the budget breakdown of Table 3, the Laboratory's
    priorities for RHIC in a constant-effort budget are to maintain an
    operations schedule of 27 weeks per year while carrying out
    essential R&D for future improvements of the machine and detectors.

-   An increment of \~3% (\$4m) in the operations budget will allow 32
    weeks per year of operations. This is regarded as the threshold
    level for a healthy program in both heavy ion and spin physics at
    RHIC.

-   Important upgrades for both the machine and detectors are now in the
    proposal phase (see Sec. III below), and will require funding over
    the next 5 years. In our planning, these upgrades are funded as
    research equipment in addition to the RHIC operations budget, for
    which the Laboratory must compete for funds with other facilities in
    the Nuclear Physics program.

# Near Term Upgrades for Detectors and Machine

The early data from RHIC experiments have provided striking
demonstration that precise and detailed measurements can be accomplished
in the complex realm of high-energy collisions of heavy nuclei, and that
these measurements can provide definitive experimental statements about
the hot, dense matter created in the initial stages of these collisions.
Each of the four RHIC detector collaborations has provided its "Decadal
Plan" for detailed study of fundamental questions in quantum
chromodynamics over the next decade, exploiting this new form of matter
as well as the availability of high-energy polarized proton collisions.

The Decadal Plans can be found at
[www.bnl.gov/henp/](http://www.bnl.gov/henp/) .

From what we know so far, it is clear that a high priority for further
exploration of deconfined matter in heavy ion collisions at RHIC
requires extension of the capabilities of the two large detectors,
PHENIX and STAR, to identify and measure the production of high-momentum
particles carrying the strangeness, charm, and beauty quarks.

Supported by R&D work that has been carried out over the past several
years, each of these detector collaborations has submitted a proposal
for an upgrade of modest cost, using advanced technology, to implement
new capability for particle detection over the next 3-5 years. These
represent the initial stages of the Decadal Plans for PHENIX and STAR.
These proposals are being submitted to DOE for initial funding in FY
2005.

The STAR group proposes to build a cylindrical array of 24,000 channels
of time-of-flight detectors, surrounding the main Time Projection
Chamber (TPC) tracking detector, with time resolution of \~100
picoseconds. This project uses the recently developed Multi-Gap
Resistive Plate Chamber (MRPC) technology, which has now been
well-proven in experiments at CERN and in a prototype detector that was
operational in STAR during the FY 2003 RHIC run. It will allow particle
identification for more than 95% of all particles produced at
mid-rapidity in STAR, including multiply-strange baryons, and, in
conjunction with the TPC and Electromagnetic Calorimeter, will provide
large samples of identified electrons from the decays of charm and
beauty particles. This project is being proposed for DOE funding of
\$4.3M, with an additional in-kind contribution from China, where the
MRPC modules will be fabricated, of \$2.3M.

The PHENIX detector collaboration proposes to build a fine-grain,
high-resolution silicon tracking detector (Silicon Vertex Tracker) to
provide precision measurement of heavy quark production (charm and
beauty) in nucleus-nucleus, proton(deuteron)-nucleus, and polarized
proton-proton collisions. It will add high-resolution vertex detection
to the existing powerful electron and hadron identification capability
of PHENIX to provide clean selection on the (rare) decays of heavy quark
states. The detector consists of two inner layers of 200μm thick silicon
with 50x425 μm^2^ active pixels, and two outer layers of 80 μm by 3.1 cm
active strips, with a total of \~1,500,000 channels. This project is
being proposed for DOE funding of \$5.6M. These funds will be
supplemented by in-kind and cash contributions from the RIKEN Institute
of about \$3M, during calendar years 2004 -- 2006.

In the meantime, with plans unfolding for long-term operation of the
RHIC facility, along with increasing demands for reliability and
stability of the beams, BNL has proposed an initiative for new
pre-injector for RHIC based on the Laboratory's development of an
advanced Electron Beam Ion Source (EBIS). The new preinjector would
consist of an EBIS high charge state ion source, a Radio Frequency
Quadrupole (RFQ) accelerator, and a short linac. Presently, one or two
35-year old Tandem Van de Graaff accelerators are used for RHIC
pre-injection, but the recent advances in the state of the art in EBIS
performance by more than an order of magnitude now make it possible to
meet RHIC requirements with a modern linac-based preinjector.

The EBIS preinjector offers the following benefits:

-   Improvements in reliability, setup time, and stability should lead
    to increased integrated luminosity in RHIC

-   Reduced operating costs and avoidance of \~ 6 M\$ in
    reliability-driven investments in the tandems

-   Elimination of two stripping stages and an 860 m long transport
    line, leading to improved performance

-   Simplification of Booster injection (few turn vs. present 40 turn)

-   Increased flexibility to handle the multiple simultaneous needs of
    RHIC, NSRL, and AGS

-   Capability to provide ions not presently available, such as noble
    gas ions (for NSRL), uranium (RHIC), or, with additional
    enhancements, polarized ^3^He (eRHIC)

The estimated cost to implement EBIS is \$17.5 M from DOE NP, if funded
over 3 years. Of this, 3.3 M\$ would come from RHIC operating fund, 6.4
M\$ from existing AIP funds, and 7.8 M\$ would be new funds required
either from NP, or with some partial contribution from NASA. A
pre-proposal for EBIS has been submitted to DOE, requesting funding to
begin in FY 2005.

The projected facility costs shown in Table 3 include funding for the
STAR, PHENIX, and EBIS upgrades.

# The Mid Term Outlook -- RHIC II

Current work at RHIC has shown that detailed exploration of the
fundamental properties of new matter produced at RHIC can be carried out
using experimental probes that carry information directly from the
thermal plasma of quarks and gluons produced in these nuclear
collisions. Such probes include the spectra of heavy quarks (charm and
beauty) that are formed in the earliest stages of the collision, and are
so massive that their dynamical properties are not lost to
thermalization at the temperatures and densities that prevail in the
plasma of light quarks and gluons. Another class of such probes is the
measurement and classification of high-momentum jets of particles
corresponding to energetically scattered quarks and gluons. Accurate
measurements of large samples allow experiments to carry out, in effect,
a tomography on the initial dense matter with "beams" of quarks and
gluons.

Light quark-antiquark pair interactions measured via the spectral
function of low-mass vector mesons give precise information on the
massive bound states of these partons in the plasma. Heavy flavor
quark-antiquark pairs, with their large current masses, are less
sensitive to chiral symmetry effects, and thus could carry information
on the deconfinement transition. Through high statistics measurements of
J/ψ, ψ', χ~c~, and upsilon (1s, 2s, 3s) we can disentangle competing
effects through comparison with lattice QCD calculations, and thus gain
direct information on how the quark-antiquark potential is modified in
the dense medium.

Quark-antiquark annihilation in a plasma should yield direct real and
virtual photons that reflect the thermal history of the system. A
precision measurement of this signal is a major goal of RHIC II.
Furthermore, while we are currently gaining insight about light quark
interactions with the medium by means of high-p~T~ probes, at RHIC II
the focus will shift to the interactions of heavy quarks, which are
expected to be substantially different due to the predicted "dead-cone"
effect. With tagged D and B mesons, we can study how heavy quarks
propagate in the medium.

These measurements, and others like them, involve extremely rare
phenomena. To cite two examples from the Decadal Plans:

-   The proposed measurement by PHENIX of the spectrum of Upsilon states
    requires a Au-Au integrated luminosity (delivered) of 10 nb^-1^.

-   The measurement of the energy loss of heavy-quark jets in a dense
    medium, proposed by STAR through the measurement of b-anti-b jet
    spectra, also requires a delivered sample of 10 nb^-1^ in Au-Au
    collisions.

At the current (design) luminosity, these measurements would require
\~160 weeks of Au-Au running to acquire. To achieve this, along with the
necessary proton-proton comparison data, would require about a decade of
facility operation in the mode described in Sec. II above.

Such measurements require beam collision rates an order of magnitude
greater than the present RHIC capability. They also require substantial
upgrades to the existing large detectors, STAR and PHENIX, to provide
enhanced sensitivity to the signatures of these processes, and to
implement electronic readout, data acquisition, and trigger systems
matched to the increased collision rates. The proposed RHIC II Project
consists of major upgrades of the RHIC collider and detectors, to
provide this new capability for studying extremely rare processes with
high precision in high-energy nucleus-nucleus, proton-nucleus, and
proton-proton collisions.

These high-luminosity heavy ion studies are essential to fully
characterize the QCD matter produced at RHIC. The matter produced at
higher energy in an eventual heavy ion program at the LHC will likely be
much more sensitive to the low Bjorken-x behavior of the parton
distribution functions and may well be fundamentally different than that
produced at RHIC. As a practical matter, the type of measurements
planned for the high luminosity physics program at RHIC will not begin
at the LHC until well after the initial survey phase of that program.
These measurements require large data samples, taken over long running
periods with multiple beam conditions. A detailed understanding from the
RHIC program may well be required to help guide the LHC experiments to
those measurements where the high energy may be exploited to best
advantage, given the limited heavy ion running time (∼1 month per year)
planned to be made available by CERN.

The present RHIC luminosity is limited by intra-beam scattering, which
is particularly severe with the high charge of the gold ions. The growth
of the beam size due to this effect can be overcome by cooling the beams
with a high intensity cold electron beam. To cool the 100 GeV/n gold
beam with 10^9^ ions per bunch in RHIC, a 54 MeV electron beam with an
average current of about 100 mA is required. The high beam power of
about 5 MW of the electron beam makes it necessary to recover the beam
energy by decelerating it in a superconducting linac, a technique that
has been successfully demonstrated at Jefferson Lab, and is presently
the focus of an R&D effort at BNL that is funded at the level of \$2M in
FY 2004. The target for Au-Au luminosity with RHIC II is 7x10^27^
cm^-2^sec^-1^, which is approximately 40 times the present design value.

The PHENIX and STAR Decadal Plans identify the detector upgrades
required to carry out the RHIC II physics program. These upgrades
comprise:

-   Precision inner tracking devices capable of directly observing charm
    and beauty decays;

-   Fast, compact, high-resolution Time Projection Chambers;

-   "hadron blind" tracking for efficient rejection of Dalitz and
    conversion electron pairs to enable measurement of low-mass lepton
    pairs and low-p~t~ direct photons;

-   Micro-electronics for fine-grain, low-mass detectors;

-   Improved data acquisition and trigger techniques to handle very
    large data volumes at high rates.

A "fast-track" program of R&D to develop the necessary technology for
STAR and PHENIX, as well as possible new detectors, for high-luminosity
running was recently reviewed by an independent committee appointed by
BNL management, the RHIC Detector Advisory Committee. The structure and
activities of this standing committee can be found at
[**www.bnl.gov/physics/rhic_DAC.htm**](http://www.bnl.gov/physics/rhic_DAC.htm).
This detector R&D is funded at the level of \$1M in FY 2004.

The cost of RHIC II is estimated at \$153M FY03 dollars. The project
will be ready to start construction around 2008, a time scale that is
consistent with that indicated in the DOE Office of Science 20-year
facility plan.

The scientific importance of the RHIC II upgrades was acknowledged in
the most recent NSAC Long Range Plan, published in April 2002, which
states: "An upgrade program such as the RHIC II initiative will allow
in-depth pursuit of the most promising observables characterizing the
deconfined state." The next Long Range Plan process is expected to begin
in 2005. If RHIC II is to be realized on the timescale foreseen here, it
will have to be a centerpiece of this plan. Thus, it will be important
over the coming year to fully develop the scientific case, the scope
(particularly with regard to detector upgrades), and the cost for this
initiative.

# The Long Term Outlook -- eRHIC

With strong roots in the heavy ion program, the spin program, and the
p(d)-A measurements in RHIC and RHIC II, eRHIC will probe the
fundamental quark and gluon structure of strongly interacting matter
with high precision. The new scientific opportunities include:

-   *[Partonic matter under extreme conditions]{.underline}.* eRHIC will
    explore fundamental nuclear physics by determining the quark and
    gluon momentum distributions in nuclei. Determination of the gluon
    distribution in nuclei is vital to understanding the complicated
    processes underway in relativistic heavy ion collisions.
    Measurements of the proton structure function at low *x* show that
    the gluon distribution grows rapidly with decreasing *x*. When the
    gluon density becomes large, it may saturate and give rise to a new
    form of matter known as the 'Color Glass Condensate'. eRHIC will
    enable a search for this exotic aspect of parton structure in nuclei
    by using gluon observables.

-   *[Hadronization in nucleons and nuclei]{.underline}.* The evolution
    of colored quarks and gluons struck by the virtual photon in deep
    inelastic scattering into observed colorless hadrons is one of the
    clearest manifestations of confinement. eRHIC will make it possible
    to observe the complete array of decay products in deeply inelastic
    scattering of electrons from the nucleon and nuclei.

-   *[Quark and gluon distributions in the nucleon]{.underline}.* eRHIC
    offers a unique capability for measuring 'flavor-tagged' structure
    functions by providing access to a wide range of final states. Quark
    and gluon distributions in nucleons, nuclei, and possibly even
    mesons can be mapped in a flavor tagged mode.

-   *[Spin structure of the nucleon]{.underline}.* eRHIC, operating at
    the highest center-of-mass energy, will provide data on the proton's
    spin-dependent structure functions at lower *x* than possible in any
    previous experiment. This information, along with that from scaling
    violations, will likely be indispensable for obtaining definitive
    answers about the quark and gluon spin contributions to the proton
    spin. Measurements of the spin structure functions g~l~ of proton
    and neutron (possibly using polarized ^3^He beams) will allow a
    precision test of the Bjorken sum rule. At highest momentum
    transfer, parity-violation in electroweak structure functions will
    be accessible. In addition, eRHIC, with its variable electron and
    proton beam energies, will also be ideal for exploring the nucleon
    spin structure in the valence region.

When eRHIC is constructed, RHIC will be providing high luminosity,
electron-cooled ion beams and high luminosity, highly polarized proton
beams. The present design of an electron-ion collider, based on the
existing RHIC machine, requires the construction of an electron
accelerator ring with 5-10 GeV energy, that will have 1/3 of the RHIC
circumference and collides with the ion beam in one of the existing RHIC
experimental areas. The electron beam is produced by polarized electron
source and then accelerated to collision energies by full energy linear
accelerator. In order to minimize electron linac size and cost the beam
recirculation is used to pass the beam twice through the same linac
accelerator sections. Positron beam also can be accelerated and used,
but the polarization is acquired then in the ring itself due to
synchrotron radiation process.

The electron ring consists of two arcs with regular FODO structure and
two straight sections: one includes the interaction region and the other
injection and rf systems. The polarization setup for the electron beam
also includes a pair of solenoidal spin rotators around the interaction
region to produce longitudinal polarization.

The RHIC ion rings already have dedicated magnet insertions, Siberian
Snakes and spin rotators, in order to provide high energy polarized
proton beam for the collisions.

Main beam parameters for the present design for high energy e-p and e-Au
collisions are shown in the Table below.

  ------------------------- ------------- ------------ ------------- ------------
                            e-p                        e-Au          
                            collisions                 collisions    

                            p             e            Au            e

  Circumference \[m\]       3833          958.25       3833          958.25

  Energy \[GeV\]            250           10           100/u         10

  Number of bunches         360           120          360           120

  Bunch population          1             1            0.01          1
  \[10^11^\]                                                         

  Beam current \[A\]        0.45          0.45         0.36          0.45

  Rms emittance             9.5/9.5       53/9.5       9.5/9.5       53/7.5
  \[10^-9^m\], x/y                                                   

  Beta function at IP       108/27        19/27        108/27        19/34
  \[cm\], x/y                                                        

  Beam size at IP \[mm\],   0.1-0.05                   0.1-0.05      
  x/y                                                                

  Beam-beam parameter, x/y  0.007/0.003   0.029/0.08   0.007/0.003   0.022/0.08

  Luminosity, \[1032 cm-2   4.4                        0.044         
  s-1\]                                                              
  ------------------------- ------------- ------------ ------------- ------------

The electron cooling of Au beam, which should be added to the RHIC rings
as part of the RHIC II project, is necessary to provide the listed
luminosity for electron-gold collisions.

Another possible design of electron machine, which brings polarized
electron beam to the collision point directly from a superconducting
energy recovery linac, is also under consideration.

The estimated cost of eRHIC, approximately \$500M FY 03 dollars,
includes the addition of a new detector or detectors optimized for e-A
and polarized e-p collisions. Construction could start around 2010 if
driven only by technical factors; a construction start later in the next
decade is foreseen by the Office of Science 20-year facility plan.

A significantly expanded scientific community will be served by the
facility when eRHIC operations commence. Segments of the QCD and
hadronic physics communities in the US (Fermilab, Jlab, SLAC) and Europe
(DESY/HERA/HERMES, CERN/Compass) are expected to participate in the
research program and are now getting involved in the formulation of the
eRHIC physics program at various levels, including IR and detector
design. Further, MIT/Bates is involved deeply in the design of the
electron ring and this involvement is expected to continue into the
construction of eRHIC.

**Appendix 1**

![](media/image1.wmf)

*[Table 2]{.underline}*

RHIC 5 Year Planning -- Constant Effort

**Summary of Beam Use Proposals**

+-------+---------+----------+---------+---------+---------+--------+
| **F   | *       | **2004** | *       | *       | *       | **     |
| iscal | *2003** |          | *2005** | *2006** | *2007** | 2008** |
| Y     |         |          |         |         |         |        |
| ear** |         |          |         |         |         |        |
+-------+---------+----------+---------+---------+---------+--------+
| # P   | d+Au    | Au+Au    | Si+Si   | Au+Au   | p+p 200 | Au+Au  |
| HENIX | 200     | 200 GeV  | 200     | 62.4    | GeV\    | 200    |
|       | GeV\    |          | GeV\    | GeV\    | 5+19    | GeV\   |
|       | 16      | 5+14     | 5+9     | 5+19    | weeks,  | 5+19   |
|       | weeks,  | weeks,   | weeks,  | weeks,  |         | weeks, |
|       | 2.7     | 123 ub-1 | 2.2     | 45 ub-1 | 62 pb-1 |        |
|       | nb-1    |          | nb-1    |         | \[159   | 840    |
|       |         | \[315    |         | \[115   | pb-1\]\ | ub-1   |
|       | p+p 200 | μb-1\]\  | \[5.6   | μb-1\]  | 60%     |        |
|       | GeV     | \        | nb-1\]\ |         |         | \[2150 |
|       |         | p+p 200  | \       |         |         | μb-1\] |
|       | 10      | GeV\     | p+p 200 |         |         |        |
|       | weeks,  | 5+0      | GeV\    |         |         |        |
|       | 0.35    | weeks    | 5+5     |         |         |        |
|       | pb-1,   | beam     | weeks,  |         |         |        |
|       | 27%     | dev      | 1.2     |         |         |        |
|       |         | elopment | pb-1    |         |         |        |
|       |         |          |         |         |         |        |
|       |         |          | \[3.0   |         |         |        |
|       |         |          | pb-1\]  |         |         |        |
|       |         |          | 50%     |         |         |        |
+-------+---------+----------+---------+---------+---------+--------+
| #     | d + Au  | AuAu     | Au or   | d + Au  | AuAu    | AuAu   |
|  STAR | 38.2M   | 5+14     | Fe 5+9  | 5+9     | 5+5     | 5+10   |
|       |         |          |         |         |         |        |
|       | 5+11    | pp 200   | Energy  | pp 200  | pp 200  | pp 500 |
|       | weeks ; | GeV 5 wk | scan    | GeV 5+5 | GeV     | GeV    |
|       |         |          |         | wk      | 5+9wk   | 5+5wk  |
|       | pp 10   |          | pp 200  |         |         |        |
|       | weeks : |          | GeV 5+5 |         |         |        |
|       |         |          | wk      |         |         |        |
|       | T 0.39  |          |         |         |         |        |
|       | pb^-^1  |          |         |         |         |        |
|       |         |          |         |         |         |        |
|       | L 0.37  |          |         |         |         |        |
|       | pb^-^1  |          |         |         |         |        |
+-------+---------+----------+---------+---------+---------+--------+
| # P   |         | AuAu@200 | pp@200  | pp@500  | P       | \      |
| HOBOS |         | 5+10(18) | 5+7(12) |         | ossible | -\-\-\ |
|       |         |          |         | 8+4     | add     | -\-\-\ |
|       |         | FeFe@200 | AuAu@63 |         | itional | -\-\-\ |
|       |         |          |         | Add.    | running | -\-\-- |
|       |         | 5+4(6)   | 5+7(12) | Species | to make |        |
|       |         |          |         |         | up      |        |
|       |         |          |         | Add.    | sho     |        |
|       |         |          |         | Energy  | rtfalls |        |
+-------+---------+----------+---------+---------+---------+--------+
| # B   |         | Au-Au    | Fe-Fe   | Au-Au   | \-\-\-\ | \      |
| RAHMS |         | 200 5+19 | 200 5+5 | 63 2+6  | -\-\-\- | -\-\-\ |
|       |         |          |         |         | \-\-\-- | -\-\-\ |
|       |         |          | pp 200  | Au-Au   |         | -\-\-\ |
|       |         |          | 5+4     | 200 2+5 |         | -\-\-- |
|       |         |          |         |         |         |        |
|       |         |          |         | pp 200  |         |        |
|       |         |          |         | 5+4     |         |        |
+-------+---------+----------+---------+---------+---------+--------+

*[Note:]{.underline} The summary for PHENIX includes the proposed size
of the [recorded]{.underline} data sample for each run. This takes
account of an assumed detector efficiency (60%) and an efficiency for
events that survive vertex cuts and other quality control (65%). The
corresponding values for the [delivered]{.underline} data rates are
shown in brackets. The latter should be compared with the numbers in
Table 1.*

*[Table 3]{.underline}* RHIC Planning: Constant-Effort Budget case (27
wks/yr)

FY 2003 entries are in actual dollars; subsequent years are in FY 2004
dollars,

+-------+---------+----------+---------+---------+---------+---------+
| **F   | *       | **2004** | *       | *       | *       | *       |
| iscal | *2003** |          | *2005** | *2006** | *2007** | *2008** |
| Y     |         |          |         |         |         |         |
| ear** |         |          |         |         |         |         |
+-------+---------+----------+---------+---------+---------+---------+
| # P   | \$6.0M  | 6.3M     | 6.5M    | 6.6M    | 6.6M    | 6.6M    |
| HENIX | (       | (27K/wk) | (       | (       | (       | (       |
|       | 24K/wk) |          | 42K/wk) | 42K/wk) | 42K/wk) | 42K/wk) |
| Ops   |         | 0.5M     |         |         |         |         |
| Costs | \$0.12M |          | 0.95M   | 0.6M    | \-\--   | \-\--   |
|       |         | 0.5M     |         |         |         |         |
| R&D   | \$0.5M  |          | 0.5M    | 0.5M    | 0.5M    | 0.5M    |
|       |         |          |         |         |         |         |
| Ops   |         |          | 2.85M   | 2.95M   | 4.2M    | 4.5M    |
| E     |         |          | VTXb,   | VTXb,   | VTXb/e, | VTXe,   |
| quip. |         |          | HBD,    | HBD,    | TPC,    | TPC     |
|       |         |          | DAQ     | DAQ     | DAQ     |         |
| Res.  |         |          |         |         |         |         |
| Equ.  |         |          |         |         |         |         |
+-------+---------+----------+---------+---------+---------+---------+
| #     | \$5.9M  | 6.4M     | 6.4M    | 6.4M    | 6.4M    | 6.4M    |
|  STAR | (       | (40K/wk) | (       | (       | (       | (       |
|       | 38K/wk) |          | 40K/wk) | 40K/wk) | 40K/wk) | 40K/wk) |
| Ops   |         | 0.5M     |         |         |         |         |
| Costs | \$0.12M |          | 1.73M   | 1.28M   | 0.3M    | \-\--   |
|       |         | 0.6M     |         |         |         |         |
| R&D   | \$0.49M |          | 0.45M   | 0.45M   | 0.25M   | 0.25M   |
|       |         | 2.7M     |         |         |         |         |
| Ops   | \$3.0M  | BEMC,    | 2.0M    | 5.0M    | 8.5M    | 4.5M    |
| E     | BEMC    | EEMC     | TOF     | TOF,    | MVTX,   | MVTX,   |
| quip. |         |          |         | MVTX,   | DAQ,    | DAQ,    |
|       | \       |          |         | FTU     | FEE,    | FEE,    |
| Res.  | [\$1.5M |          |         |         | FTU     | TPC     |
| Equ.  | EEMC\]  |          |         |         |         |         |
+-------+---------+----------+---------+---------+---------+---------+
| # P   | \$0.86M | 0.89M    | 0.89M   | 0.89M   | .89M    | \-\-    |
| HOBOS | (       | (10K/wk) | (       | (       | (       | \-\-\-\ |
|       | 10K/wk) |          | 10K/wk) | 10K/wk) | 10K/wk) | -\-\-\- |
| Ops   |         | 0.1M     |         |         |         | \-\-\-- |
| Costs |         |          | 0.1M    | 0.1M    | \-\-\-- |         |
|       |         |          |         |         |         |         |
| Ops   |         |          |         |         |         |         |
| Equ.  |         |          |         |         |         |         |
+-------+---------+----------+---------+---------+---------+---------+
| # B   | \$0.78M | 0.8M     | 0.8M    | 0.8M    | \-\-\-\ | \-\-    |
| RAHMS | (       | (10K/wk) | (       | (       | -\-\-\- | \-\-\-\ |
|       | 10K/wk) |          | 10K/wk) | 10K/wk) | \-\-\-- | -\-\-\- |
| Ops   |         | 0.11M    |         |         |         | \-\-\-- |
| Costs |         |          | 0.1M    | 0.075M  |         |         |
|       |         |          |         |         |         |         |
| Ops   |         |          |         |         |         |         |
| Equ.  |         |          |         |         |         |         |
+-------+---------+----------+---------+---------+---------+---------+
| # RCF | \$5.18M | 5.64M    | 6.13M   | 6.13M   | 6.13M   | 6.13M   |
|       |         |          |         |         |         |         |
| Ops   | \$2.0M  | 2.0M     | 3.4M    | 2.0M    | 2.0M    | 2.0M    |
| Costs |         |          |         |         |         |         |
|       |         |          |         |         |         |         |
| Ops   |         |          |         |         |         |         |
| Equ.  |         |          |         |         |         |         |
+-------+---------+----------+---------+---------+---------+---------+
| #     | \$90.3M | 90.9     | 90.9M   | 94.9M   | 94.9M   | 92.8M   |
|  C-AD | (       | (        | (3      | (       | (500K)  | (500K)  |
|       | 350K/w) | 350K/wk) | 50K/wk) | 500K/w) |         |         |
| Ops   |         |          |         |         | 2.0M    | 2.0M    |
| Costs | \$0.9M  | 2.0M     | 2.0M    | 2.0M    |         |         |
|       |         |          |         |         | 4.5M    | 4.5M    |
| R&D   | \$4.4M  | 4.5M     | 4.5M    | 4.5M    |         |         |
|       |         |          |         |         | 2.5M    | \-\--   |
| Ops   | \-\--   | \-\--    | 2.5M    | 2.5M    | EBIS    |         |
| E     |         |          | EBIS    | EBIS    |         |         |
| quip. |         |          |         |         |         |         |
|       |         |          |         |         |         |         |
| Res.  |         |          |         |         |         |         |
| Equ.  |         |          |         |         |         |         |
+-------+---------+----------+---------+---------+---------+---------+
| #     | \$0.86M | 0.90M    | 0.90M   | 0.90M   | 0.90M   | 0.90M   |
| ALD/U |         |          |         |         |         |         |
| sers  |         |          |         |         |         |         |
+-------+---------+----------+---------+---------+---------+---------+
| # T   | \       | \$111.8M | \       | \       | \       | \       |
| otals | $109.8M | (437K)   | $111.6M | $116.6M | $115.8M | $112.8M |
|       | (432K)  |          | (452K)  | (602K)  | (592K)  | (582K)  |
| Ops   |         | \$3.0M   |         |         |         |         |
| costs | \$1.1M  |          | \$4.7M  | \$3.9M  | \$2.3M  | \$2.0M  |
|       |         | \$7.8M   |         |         |         |         |
| R&D   | \$7.4M  |          | \$9.05M | \$7.5M  | \$7.15M | \$7.25M |
|       |         | **\$     |         |         |         |         |
| Ops   | **\$1   | 122.6M** | **\$1   | **\$1   | **\$1   | **\$1   |
| E     | 18.4M** |          | 25.3M** | 28.0M** | 25.3M** | 21.9M** |
| quip. |         | Pres:    |         |         |         |         |
|       | Actual: | \$121.1M | \$7.35M | \       | \$15.4M | \$9.0M  |
| ##    | \       |          |         | $10.55M |         |         |
|  Ops  | $118.0M | \$2.7M   |         |         |         |         |
| Total |         |          |         |         |         |         |
|       | \$3.0M  |          |         |         |         |         |
| Res.  |         |          |         |         |         |         |
| Equ.  |         |          |         |         |         |         |
+-------+---------+----------+---------+---------+---------+---------+