NEWMAN LABORATORY FUTURE PLANS
D. Rice, M. Tigner, Newman Laboratory, Cornell University, Ithaca NY, USAAbstract
After completing collection of a substantial data set onthe Υ(4S) resonance, we hope to expand CESR running tocover the c.m. energy range from 3.1 to 11.2 GeV. Inaddition to an R&D program in specific technical areas,
work is proceeding on a new type of synchrotron radiation
source.
In particle physics we foresee joining
collaboration on an energy frontier machine within thisdecade.

1 CESR PHYSICS PROGRAM
33-2-1

CESR [1] operation above 10 cm -sec has provided a
substantial data set for the CLEO collaboration on theΥ(4S) resonance. The CLEO physicists are bringing 25-1fb to conferences in summer, 2001.
In late June CESR will shut down for approximately 3months to install superconducting quadruple magnets inthe interaction region and complete the installation of a
new synchrotron radiation facility (CHESS) beam line(“G-line”).
An approximately 8 month run on various Υ resonancesfrom 4.7 to 5.5 GeV beam energy will start in September.
During this period machine performance in the 1.5 to 2.5
GeV beam energy range and beam dynamics associatedwith round beam operation will be evaluated in machinestudies.
Charm physics running with CESR beam energies from1.55 to 2.5 GeV might begin in early 2003 after a
shutdown to install radiation enhancing wiggler magnets.

2 THE CESRc PROGRAM
The CESRc project will add super conducting wigglers
in the CESR ring, enabling effective operation from 1.5
through 5.6 GeV beam energy, giving access to charm andb thresholds using the same apparatus.
This program will provide definitive tests of new,percent level lattice QCD results and predictions ofspecific glue rich states of matter. In addition to having
intrinsic merit for physics and providing support for
ongoing b-physics measurements, the data will probe
deeply the only well developed strongly coupled theory
we have, QCD, a likely forerunner of the theories needed
beyond the current energy frontier.
CLEO, with its good resolution and 94% hermeticity
will be the most powerful detector ever used on thisphysics.

The 3 year run beginning in 2003 is projected to collect
6 million tagged D decays, 0.3 million DS, and billions ofJ/Ψ decays, all nearly background free.
We have looked at many accelerator physics andengineering aspects of the low energy running. The
primary issues are related to restoration of the radiation
damping and horizontal emittance to levels comparablewith 5.3 GeV running.
In a “natural” storage ring, the damping decreases
proportional to the beam energy to 1/3 power, and theemittance in direct proportion to the beam energy. The
scaling of several important parameters with therelativistic factor, γ are:Damping time:τ ∝ γ −3

4Synchrotron radiation power: PR ∝ γ

Horizontal Emittance:
Energy spread:εX ∝γ2Q X3σE∝γ
E0The luminosity decreases with energy primarily for 3
reasons:
1) The electrons are “less stiff” and their trajectories
are affected more by the space charge forces of theopposing beam.
2) The beam emittance decreases, increasing thespace charge density for a given number ofelectrons, again increasing the space chargeforces.
3) The decrease of damping reduces the “cooling” ofthe electrons heated by the beam-beam interaction.
CESR C will mitigate these effects by adding radiation
via wiggler magnets. Some basic parameters for 1.885
GeV operation maya be found in Table 1.
Parameter
Value
Beam Energy
1.885 GeV
32-2-1Luminosity
3x10 cm -sec
Current/beam
0.13 A
Bunches/beam
9x5
Beam-beam Param.
0.04
β function at i.p. H/V
0.9/ 0.01 m
Trans. Damping Time
0.05 sec-3
Rel. Energy Spread
0.8 x 10
Table 1: CESR C Operating Parameters2.2 Wiggler Technology
Some 18 m of wigglers at about 2T field areenvisioned.
This length will be achieved throughinstallation of 14 small modular units having 5 cm beam
aperture commensurate with the present CESR aperture.
Most economical will be to place the wiggler units as
close to the south as possible to limit the extent of theneeded cryogenic infrastructure and to minimize theadded boundary conditions on the ring optics. In order tolimit further the total extent of the wiggler array, somerearrangements of the present dipoles will be made,affording further available space near the central lab
facilities.
Achieving damping within ~2 times the 5.3 GeV values
implies that 90% of the radiation in the ring will comefrom the wigglers. Second and third order nonlinearities
in the wiggler fields become important and must be
considered in wiggler and lattice design.

2.3 Other accelerator physics and engineering
issuesIn addition to the damping time, emittance and beambeam limits mentioned above, there are further
considerations necessary in assess in the feasibility ofextending the energy range and estimating the achievable
luminosities at the desired lower operating energies.
Among them are:parasitic crossings; solenoid
compensation; beam generated detector backgrounds;
non-linearities in the existing optics and the additional
non-linearities introduced by the wigglers; Touschek
scattering; coulomb scattering on the residual gas; vacuum
pumping; coupled bunch instabilities; bunch lengthening;
injection and injector operation.
Each of these issues has been examined in considerable
detail using well established calculational methods andsimulations and the results used to estimate expected
luminosities and luminosity lifetimes. The beam-beam
parameter values (ξ=0.04) are conservatively chosen
based on the appropriate damping decrement and achievedvalues measured at comparable machines world-wide.
Some of the accelerator physics issues mentioned havealready been examined experimentally, namely thedistributed ion vacuum pump performance at low
magnetic field in the ring has been shown to besatisfactory and the performance of the injector at 1.5
GeV is good. Most of the others will be exploredexperimentally after installation of the new interaction
region superconducting quadrupoles in summer of thisyear (2001).
Super conducting IR quadrupoles [2] will replace thepermanent magnet IR quadrupoles during the summer of
2001, making optics for low energy operation realizable.
The new quadrupoles provide the capability for β*V assmall as 7 mm in flat beam optics, and β* of 3 cm in bothplanes for round beam optics.
CESR has operated with 4 super conducting RF cavities[3] since November, 1999. Two additional cavities havebeen planned for installation by the end of 2002. Thesewill provide the added field gradient needed to shorten
bunch lengths to 1 cm for compatibility with the planned 1
cm operating β*V with the S.C. IR quads. Furthermore, theadditional cryogenic capability installed for the newcavities will have sufficient spare capacity for the wiggler
modules.

2.4 Schedule
A prototype wiggler module will be completed by theend of 2001. By that time we will also have amanufacturing plan in place to produce the 16 wiggler
units (including 2 spares) for CESR C operation.
Operation at 1.885 GeV might begin in early 2003.

3 WORLD FACILITY COLLABORATION
For our future particle physics program the Cornell
group is expecting to join an international collaboration inbuilding and operating a linear collider via the Global
Accelerator Network. We expect to be fully engaged inthis new activity by mid decade.

4 ENERGY RECOVERY LINAC
Newman Laboratory will continue it’s on campus
activities in providing synchrotron radiation for x-ray
thexperiments. An exciting proposal for a 4 generation
source incorporates an energy recovery linac to providerd
100x the brilliance of 3 generation sources and subpicosecond timing. [4]The state-of-art of photocathode electron sources makes-6
a source with 2x10 m-rad-MeV normalized emittancepossible. Accelerating such a beam to 5-7 GeV without
appreciable dilution would produce a source of
unparalleled brilliance and timing capability. This can bedone with a single pass linac-wiggler arrangement.
Without energy recovery the mains power required
would approach 1 GWatt. However, by recirculating thebeam through the high Q super conducting linac, the beamenergy can be recovered and passed on to the newly
accelerated beam.
A 2.5 cm period, 25 m long undulator with a 5 GeV,
22
100 mA beam would provide a brilliance of 1022
Detailed design withphotons/sec/mm /mr /0.1%BW.
optics have been worked out at Cornell and a proposal for
a 100 mA, 100 MeV prototype facility is in preparation.

REFERENCES[1] S.B.Peck, D.L. Rubin, “CESR Performance andUpgrade Status,” IEEE/APS PAC’99, New York, p.
285 (1999)[2] J. Welch et al., “CESR Phase III Interaction Region,”
IEEE/APS PAC’99, New York, p. 3221 (1999)[3] S. Belomestnykh, et al., “Running CESR at High
Luminosity and beam Current with Superconducting
Cavities,” EPAC’00, Vienna, p. 2025 (2000)[4] http://www.erl.chess.cornell.edu