Antiproton Physics Antiproton Physics ExperimentsExperiments

Keith Gollwitzer -- Fermilab

•Antiproton Sources•Accumulator Antiproton Physics Experiments

–Precision measurements•Method•Charmonium•XYZ States

•Antiproton Physics Experiments Beyond the Accumulator

XYZpp

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Yearly Production

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CERN FNAL

Antiproton SourcesAntiproton Sourcese10 A

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Fermilab and CERN have/had the only Antiproton Sources.Currently, the operating Antiproton Sources are used for the Tevatron low energy/trapping programs, respectively. Schedules beyond 2010 do not exist for either Antiproton Source.

GSI (Darmstadt, Germany) is to construct an Antiproton Source as part of the Facility for Antiproton and Ion Research project. At the design peak production rate, FAIR will make <1014 antiprotons/year starting ~2016.

Fermilab has the best Antiproton Source now and the future

Accumulator Antiproton Accumulator Antiproton PhysicsPhysics

• Precision measurements of Charmonium

• Precision measurements of XYZ States

• Measurements of continuum processes– Associated production of

Charmonium– Proton Form Factor– Multi-meson final states

• Searches/confirmations – Excited Charmonium

states, – Exotics/hybrids – Glueballs

• Partial Rate Asymmetries of Hyperon Decays– CP violation

• Rare Hyperon Decays– Dimuon resonance search

• Relativistic Antihydrogen– Lamb Shift

• Open Charm– D-mixing; CP violation

• Charmonium produced in different nuclear targets

• Polarized hydrogen target – Electric and magnetic

contributions to the Proton Time-like Form Factor

Beam Profiles

Breit-Wigner line shape

Beam Scan of ψ(2S)

Most precise measurement of the ψ(2S) width despite

much smaller statistics than e+e- experiments

Precision Measurement Method

Convolution results in the

observed cross section

The precision of the mass and width of the c needs to be improved

E760 & E835 only reported pbarp

Need to observe c in more channels

1P1 or hc JPC = 1+-

The hc mass is important to understanding hyperfine splitting.

The hc width has not been measured. Need more channels.

pbarp hc c ()

E760: pbarp hc J/ 0 (e+e-) ()

Searched for pbarp ηc/

PDGM = 3637 ± 4 MeVГ = 14 ± 7 MeV

Need more channels.

Also in March 2008 CERN Courier

Study in pbarp in the A

ccumulator?

X(3872) has been seen to decay via Charmonium and Charm Mesons

resulting in different masses. 1 or 2 states? Only upper limit on width.

Accumulator could scan this resonance(s)

Charmonium ReactionsCharmonium Reactions

0/ Jpp

pppp // Jpp c

eeψJpp /

/Jpp /0 Jpp c

/cpp

pppp c / /

cpp

0cpp

0cpp

pphpp c

pppp c 0

2cpp

2cpp

0/Jhpp c

/Jpp

/1 Jpp c

pppp c 2

pppp c 2

ppJpp /

ccpp /

/cpp

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cpp

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pppp c

cpp

cpp

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XYZ ReactionsXYZ Reactions

pp X(3872) D0D00

pp X(3872) D0D*0

pp Z(3930) D D

pp X(3940) D*D

pp X(4160) D*D*

pp X(3872) J/ pp X(3872) J/ pp X(3872) J/ pp Y(3940) J/ ωpp Y(4008) J/ pp Y(4260) J/ pp Y(4260) J/ KK

pp J/ 0

pp J/ ωpp c 0

pp c ωpp c0 0

pp c1 0

pp c2 0

pp / 0

pp c/ 0

pp 0pp

pp J/ pp J/ /

pp c pp c /

pp c0 pp c1 pp c2 pp / pp c

/ pp pp ω

pp J/ pp J/ pp c pp c pp c0 pp c1 pp c2 pp / pp c

/

pp 0ωpp /ω

pp 0pp 0/

pp 00

pp /

pp /

pp //

pp ωpp ωω

pp φφpp KK

pp

eeppContinuum ProcessesContinuum Processes

Facilities Beyond the Facilities Beyond the AccumulatorAccumulator

• Low Energy Ring/Stopping– Decelerate in MI and extract to new ring

capable of further deceleration and cooling• Slow Antiprotons and Trapping• Antihydrogen and Antiprotonic Atoms

• Medium Energy Ring– Accumulator freed from experiment to stack full

time– Extend energy reach of experiment; electron

cooling?

• Bottomonium – Precision Measurements– Small collider (asymmetric?) – Internal jet target (50-70GeV/c)

SummarySummary• The world’s most productive Antiproton

Source is here at Fermilab and could continue to be for the next decades

• The Fermilab Accumulator has hosted successful experiments

• The Fermilab Accumulator can be ready to perform experiments ~6months after Run II

• Many different measurements can be made• First physics results could be in 2011• New rings could exploit the Fermilab

Antiproton Source capabilities.

Extra Slides

Charmonium Masses and Widths11

F i g u r e1 . 7 :Thecharmoniums pectrumbe l ow t h eopencharmt h r e s h o l dwitht h e1P1

l oc a t e da tt h es p i nwe i g ht e dave r a g eo ft h et r i p l e tP wave s t a t e s .Thick s o l i dl i n e s

d e n o t et h es t a t e swhich a r ed i r e c t l yp r oducedby e+e# a n n i h i l a t i o n ;s t a t e swhichwe r e

unseeno rneededt obe ve r i f i e dbe f o r et h i sexperiment a r er e p r e s e nt e dby t h i ckbroken

l i n e s .Theknown andexpe c t e dh a d r o n i cande l e c t r o m a g n e t i ct r a n s i t i o n sanddecay st h a tE760cand e t e c ta r es h own.

E760/E835 main purposes were to do precision measurements of the

Charmonium spectrum as well as the

discovery/confirmation of 1P1 and ηc

/

TechniqueThe Accumulator is the Spectrometer

Annihilation of pbar p to form each state

All quantum numbers can be formed

Detector is a big scalar

Scan beam energy to map out resonance

“Clean” electron/positron Signals

/ J/ X e+e- X

/ e+e- Threshold CernekovShower shape

1-- State Scans (1990-1)

PRECISION

PRECISION

PRECISION

PRECISION 1 & 2 Scans

0 Scan

Could be more precise with more integrated luminosity

Interference will be shown later

pbarp 0 0

0

Two Photon Final States

Takes work to understand the feed-

down from multi-photon final states

CCAL threshold of 5/20MeV

These data are from the c peak

pbarp 0 & 2 In

terf

eren

ce n

ext

slid

e

Interference can be your friend

The continuum “amplifies” the resonance

E835 example in 4 photonspbarp c0 0 0 , , /

Should expand interference analyses to

more channels; in particular pbarp at 90o

in the center of mass system

Search using inclusive J/

c/ s

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The States

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1 - -

2 + +

1 + +

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/0 12

c c/hc

pbarp +

pbarp two neutral mesons

00 0

Scaling Rule?

pbarp two neutral particles

Proton Magnetic Form Factor

pbarp 6

Steering Group Report• P19 Precision Physics – muons: “An intense 8 GeV beam and the

Accumulator and Debuncher rings, …, would make this LFV search possible.”

• P20 Precision Physics – Charm and hyperon physics with antiprotons (1 paragraph sub-section)

• P24 SNuMI: “SNuMI uses antiproton facilities….”• P25 Project X: “…compatible with reconfigurations of the Debuncher

ring and the Tevatron to support slow spill programs….”• P25 Existing Rings: Debuncher Slow Extraction (1 paragraph sub-

section)• P27 Summary paragraph: “The SNuMI project is based on reusing

existing antiproton rings for proton accumulation.”• P44 Appendix G Facilities Considered: table entry of Antiproton

Facility with Performance Parameters of “Incompatible with SNuMI. Minor hit on proton availability from Project X”

• Most overview presentations of the Steering Group Report and Project X spend time discussing reusing the Antiproton Source rings (sometimes even emphasizing existing accelerator) with little or no mention of Antiproton Physics