Transcript Spin Physics with Antiprotons FNAL Antiproton Accumulator • world record p stacking rate (≈ 2 ×1011/hr) • jet target experiments E760/E835 ( L ≈

Spin Physics with Antiprotons
FNAL Antiproton Accumulator
• world record p stacking rate (≈ 2 ×1011/hr)
• jet target experiments E760/E835 (<2000)
L ≈ 2 ×1031cm-2 s-1 ( → 2 ×1032cm-2 s-1 )
• Precision QCD tests and spectroscopy
• Physics of Flavour Studies
• Studies of basic symmetries (CP, CPT)
gas target
• Spin dependence  Polarized
p beam (!?)
{
(In collaboration with Y.Onel et al., U.of Iowa)
Project X Workshop
Aldo Penzo
INFN-Trieste
Fermilab, Nov. 07
INFN
Istituto Nazionale
di Fisica Nucleare
Sezione di Trieste
Spin Physics with p
(Some References)
• S. Brodsky - Testing QCD in Antiproton Reactions,
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SLAC-PUB-4451 (Oct 1987)
J-M. Richard - Spin and Flavour,
arXiv:nucl-th/9302003v1 (Feb 1993)
- Antiproton induced reactions,
arXiv:nucl-th/9406025v2 (Jul 1994)
W.A. Mok, K.J. Sebastian - Charmonium states in
polarized p-pbar collisions,
N. Cim. A110, 429 (1997)
• V. Barone, A. Drago and P. Ratcliffe –
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QCD tests
Flavour,
pp → LL
Symmetries
Spectroscopy
p↑p↑→ l+ l- X
(Drell-Yan)
Phys. Rep. 359, 1 (2002)
M.Anselmino et al. - Phys.Lett. B594, 97 (2004)
Transversity
R. Jaffe - Open questions in high-energy spin physics,
MIT-CTP-3230 (Jan 2002)
New Physics ?
J. Ellis - Polarization puts a New Spin on Physics,
arXiv:hep-ph/0701049v1 (Jan 2007)
(Polarized) gas target
in p Accumulator
• 8 GeV p in
AP2 line
• 120 GeV p
(8x1012) on
target
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Target
Type
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Density
[at./cm3]
Thickness
[cm; at./cm2]
Luminosity
[cm-2 s-1]
<P>
Mol. Cluster
Atomic Beam
4x1014
6x1011
0.7; 3x1014
1.0; 6x1011
2x1032
4x1029
0.0
0.9
Storage Cell
5x1012
20.; 1x1014
7x1031
0.8
Polarized target – single spin AN measurements
- spin correlations in pp → LL
Polarized antiprotons? ... WHY?
- q – q annihilation in ⇈/⇅ spin states
•
Sharper spectroscopy selection rules
• Stronger QCD tests
• Nucleon transversity via Drell-Yan: p↑p↑→ l+ l- X
Many theory/phenomenology papers, see:
S. Brodsky, E. Leader, J. Ellis, J-M. Richard, …
Impressive effort (PAX at FAIR, GSI) for pol. p :
huge investment (>10 2 M€ ), long-range project (> 2014)
Polarized Antiprotons: HOW?
Workshop on Polarized Antiproton Sources
Antihyperon Decay
Spin Filter
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Stochastic Tecniques
Dynamic Nuclear Polarization
Syncrotron Radiation emission
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Antiproton Scattering
Repeated Stern-Gerlach
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Antihydrogen formation
Penning trap
Channeling
...........???
Experimental
proof
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Technical
tests
Bodega Bay CA, April 1985; O. Chamberlain, A. Krisch, A. Lin
AHWD: p → (Lo) → p↑
(2 x 105 p↑/ 1012 prim. p)
Workshop (29-31 Aug 2007) at APES: p → p (p) → p↑(p)
Cockcroft Institute, Daresbury (2 x 103 p↑/ 1012 prim. p)
Lab, UK (mainly spin filter)
AHWD vs APES
FM = I * P2
• p→p
• p → (Lo) → p↑
• p → p (p) → p↑(p)
p/p
2x10-5
2x10-7
4x10-9
<P>
0.0
~ 0.45
~ 0.30
Spin Filter – Spin Splitter
More speculative methods to produce p↑:
• Spin filter: differential absorption of p spin states
(IF s⇈≠ s⇅); polarized storage cell
• Spin splitter: Stern–Gerlach separation of p spin
states; spin rotator+2 quadrupoles
SF tested with protons (P ~ 0.04, I/Io ~ 0.1); but p ???
If SS tested with protons, p OK
Spin Filter – baseline for GSI
Prospects for p spin physics
Medium term:
• FNAL Antiproton Source survive collider era:
– Challenging, fresh physics!
– Moderate cost upgrades?
• Polarized gas target to complement E835 jet
• AHWD secondary beam (~ 8 GeV) from Main
Injector (40 GeV) to antiproton accumulator?
Longer term:
• Tests of Spin Filter/Splitter in Accumulator Ring
(+ gas target)
Benchmark processes
q
q
g*
< s A> ≈
10-34
cm2
e+
q
e-
q
g
s
<sA> ≈ 10-30 cm2
s
(4 ≤ M ≤ 9 GeV)
From MI (40GeV) to p accumulator (8GeV)+(pol.)H target
[L ≈ 1014x1010x6.105 ≈ 6x1029 cm-2 s-1, PB ≈ 0.45, PT ≈0.8]
dADY ≈ ± 0.10
dALL ≈ ± 0.04
(T= 107 s)
(T= 107 s)
Back-up slide
Throw in numbers…
Consider p →
→ p↑ in 2 cases:
- From MI (40GeV) to p accumulator (8GeV)+(pol.)H gas target
[L ≈ 1014x1010x6.105 ≈ 6x1029 cm-2 s-1, PB ≈ 0.45, PT ≈0.8]
- From SY (120 GeV) to sec. line (30GeV p)+pol. target (NH3)
[L ≈ 2x106x3x6x1023 ≈ 6x1030 cm-2 s-1, PB ≈ 0.45, PT ≈0.2]
Asymmetry error is dA ≈ 1/(PB PT Nev)
(Lo)
For p↑p↑→ l+ l- X (D-Y), <sA> ≈ 10-34 cm2 (4 ≤ M ≤ 9 GeV)
In a period of 107 s, dADY ≈ 1/(0.45x0.8x25) ≈ ± 0.10 and
dADY ≈ 1/(0.45x0.2x77) ≈ ± 0.14 for the 2 cases respectively.
For p↑p↑→ Lo Lo X, <sA> ≈ 10-30 cm2 ; in a period of 105 s
dALL ≈ 1/(0.45x0.8x230) ≈ ± 0.01 and dALL ≈ ± 0.02. If the
hyperons’ spin are analyzed, dCLL ≈ 1/(0.45x0.2x0.36x230)
≈ ± 0.04, and the same for the second case.
Back-up slide
… close to ballpark…?!