Accelerator R&D towards eRHIC Yue Hao, C-AD For the eRHIC Team.
Physics at the future eRHIC - Brookhaven National … · Physics at the future eRHIC Salvatore...
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Physics at the future eRHIC Salvatore Fazio Brookhaven National Laboratory – Physics Department eRHIC: an Electron-Ion Collider at Brookhaven Lab eSTAR ePHENIX 30 GeV 30 GeV 100 m Linac 2.45 GeV Linac 2.45 GeV Coherent e-cooler Polarized e-gun Beam dump 0.60 GeV 5.50 GeV 10.4 GeV 15.3 GeV 20.2 GeV 25.1 GeV 30.0 GeV 3.05 GeV 7.95 GeV 12.85 GeV 17.75 GeV 22.65 GeV 27.55 GeV 0.6 GeV 0.6 GeV 27.55 GeV New detector Imaging Spin physics Satura.on -1.5 -1 -0.5 0 0.5 1 1.5 -1.5 -1 -0.5 0 0.5 1 1.5 -1.5 -1 -0.5 0 0.5 1 1.5 [0.0, 0.01] [0.0, 0.02] [0.0, 0.05] [0.0, 0.10] [0.1, 0.20] [0.2, 0.30] [0.3, 0.40] [0.4, 0.50] [0.5, 0.60] [0.6, 0.70] [0.7, 0.80] [0.8, 0.90] [0.9, 0.94] [0.9, 0.97] [0.9, 0.99] [0.9, 1.00] b y (fm) bx (fm) bx (fm) q⇑(x=10-3,b → ,Q2= 4 GeV2) q(x=10-3,b → ,Q2= 4 GeV2) -0.04 -0.02 0 0.02 0.04 -0.04 -0.02 0 0.02 0.04 -0.04 -0.02 0 0.02 0.04 10 -2 10 -1 1 DSSV DSSV and EIC 5 GeV on 100 GeV & 5 GeV on 250 GeV all uncertainties for Δχ2= 9 xΔu xΔd xΔs x Q 2 = 10 GeV 2 xΔg x -0.2 -0.1 -0 0.1 0.2 0.3 10 -2 10 -1 1 many new smaller partons are produced Proton (x, Q2) Proton (x0, Q2) x0 >> x Low Energy High Energy parton “Color Glass Condensate” (F L - F L leading twist )/F L (F L - F L leading twist )/F L Au (A=197) proton -5 -4 -3 -2 1 2 3 -10 -8 -6 -4 -2 0 log 10 (x) log 10 (Q 2 ) log 10 (x) log 10 (Q 2 ) -5 -4 -3 -2 1 2 3 -10 -8 -6 -4 -2 0 ABSTRACT An Electron-Ion Collider facility (EIC) [1], a project although known as eRHIC, is under consideration at the Brookhaven National Laboratory (BNL). eRHIC is a machine designed to collide an electron beam with the currently existing RHIC hadron beam (protons and nuclei), capable of largely varying the center-of-mass energy produced in the collision and the polarization of both beams. The use of a high energy electron beam, the high luminosity of the machine expected in the order of 10 34 events/cm 2 *s at the highest center-of-mass energy, and the new specifically designed detector, will make eRHIC the ideal “microscope” for investigating, with an unprecedented precision, the three-dimensional picture of the internal structure of the proton. Here I briefly review the most important topics of the broad physics case we aim to carry on at eRHIC and the large impact that such machine can have versus the current knowledge of quarks and gluons (the building blocks of the matter) and thus how they contribute to all the basic properties that characterize a single nucleon, such as mass, charge and spin. Beam energies: Polarized electrons: 5 to 20 GeV Polarized protons: 100 to 250 GeV Ions: 50 to 100 GeV/nucleon No other tunnel required: electron beam line will be added in the present RHIC tunnel (cheep and green) Up to 3 experimental locations along the ring Very high luminosity 10 34 events/cm 2 *s (100 times higher than the previous electron-proton collider: HERA) Physics goals Tomography of a nucleon/nucleus in three dimensions Understand the properties of gluons, which dominate the mass and density of the visible matter in the Universe! Determine quark and gluon contribution to the proton spin: solve the “spin puzzle” Physics motivation What is the space-time and momentum distribution of quarks and gluons in nucleons? What is the role of strong gluon fluids and parton saturation effects in scattering of nuclei? What is the polarization of gluons in the region where they are most abundant? What is the flavor decomposition of the polarized sea-quarks? Newly designed dedicated detector • Hermetic Central Tracking Detector • Good EM calorimeter resolution with fine granularity • Preshower electromagnetic calorimeter • Very forward calorimeter and proton spectrometer 3D picture in coordinate space 3D picture in momentum space Result from the HERA Collider: whilst the valence quarks dominate at large x values (~0.3) for x < 10 1 the nucleon density is dominated by gluons Gluon satura7on: when gluon density becomes large enough, small gluons are believed to combine together as described in the Color Glass Condensate (CGC) theory [3], but this state of the maJer to the present remains experimentally uninves.gated References: [1] White Paper on the Electron Ion Collider – Available online: http://skipper.physics.sunysb.edu/~abhay/eicwp12/draft/EIC-WhitePaper-11232012.pdf [2] S. Fazio, T. Toll, and T. Burton – “eRHIC: An UltraHighResolu7on Electron Femtoscope” http://www.bnl.gov/rhic/inside/news.asp?a=2465&t=today [3] E. Iancu, A. Leonidov, and L. D. McLerran, Phys. LeJ. B510, 133 (2001) [4] J. Bartels, K. GolecBiernat, and L. Motyka, Phys. Rev. D81, 054017 (2010) The x variable: known as “x of Bjorken” it is the frac7on of the total momentum of the nucleon carried by the parton (quark or gluon) par7cipa7ng in the interac7on Parton densi,es Access satura7on: eRHIC will be sensible to satura.on (e.g. in e+Au collisions) [1]. Figure shows the simulated measurement of the longitudinal structure func7on F L for both protons and Au at eRHIC, satura.on effects are much more prevalent in e+Au [4]. Gluon satura7on effects are expected to be higher in heavy nuclei eRHIC will be an ideal to explore the satura7on regime! What is the spin: In quantum mechanics, spin is the intrinsic angular momentum carried by a particle Open question: How quarks and gluons contribute to the spin of the proton? Goal: solve the “spin puzzle” Open questions: In a fast moving nucleon the longitudinal size squeezes like a “pizza” but transverse size remains about 1 fm Can we resolve transverse coordinate or momentum space in a parton density picture? Goal: nucleon tomography! Electron Proton/ Nucleus Electron beams will be our microscope light, used to investigate the structure of nucleons/nuclei p e (Existing) (to be build) Op7cal microscope eRHIC Paul C. Lauterbur Sir Peter Mansfield Nobel Prize, 2003: "for their discoveries concerning magnetic resonance imaging" nucleon eRHIC Tomography is today commonly used in hospitals @ eRHIC we will do the same to nucleons and nuclei The idea: building a large quantum “femto”-scope [2]... ONLY at eRHIC ! Unlike LHC, eRHIC will polarize both electron and proton/nuclei beams and will extend of 1000 7mes the currently available xBjorken range available at fixed target experiments [1], allowing to solve the puzzle! Valence quarks: contribute ~ 30% 60% ??? Gluons: RHIC suggest ~ 10% Δg(x,Q 2 ) =g (x,Q 2 )g (x,Q 2 ) The predicted impact of eRHIC Acknowledgements All my research on eRHIC is carried on as member of the BNL EIC Science Task Force – therefore I would like to thank all my collaborators: Elke Aschenauer, Thomas Ullrich, Thomas Burton, Ramiro Debbe, BenedeJo di Ruzza, Jamie Dunlop, Wlodek Guryn, MaJ Lamont, J. H. Lee, Dieter Mueller, Hubert Spiesberger, Marco Stratmann, Tobias Toll, Liang Zheng Please visit our webpage: https://wiki.bnl.gov/eic/index.php/Main_Page
Transcript of Physics at the future eRHIC - Brookhaven National … · Physics at the future eRHIC Salvatore...
Physics at the future eRHIC Salvatore Fazio
Brookhaven National Laboratory – Physics Department
eRHIC: an Electron-Ion Collider at Brookhaven Lab
eSTAR
ePHENIX
30 GeV
30 GeV
100 m
Linac
2.45
GeV
Linac 2.45 GeV
Cohe
rent e
-coole
r
Polarized
e-gun
Beamdump
0.60 GeV
5.50 GeV
10.4 GeV
15.3 GeV
20.2 GeV
25.1 GeV
30.0 GeV
3.05 GeV
7.95 GeV
12.85 GeV
17.75 GeV
22.65 GeV
27.55 GeV
0.6 GeV
0.6 GeV
27.55 GeV
New detector
Imaging
Spin physics
Satura.on
-1.5 -1 -0.5 0 0.5 1 1.5
-1.5
-1
-0.5
0
0.5
1
1.5
-1.5 -1 -0.5 0 0.5 1 1.5[0.0, 0.01][0.0, 0.02][0.0, 0.05][0.0, 0.10][0.1, 0.20][0.2, 0.30][0.3, 0.40][0.4, 0.50][0.5, 0.60][0.6, 0.70][0.7, 0.80][0.8, 0.90][0.9, 0.94][0.9, 0.97][0.9, 0.99][0.9, 1.00]
b y (f
m)
bx (fm) bx (fm)
q!(x=10-3,b",Q2 = 4 GeV2)q(x=10-3,b",Q2 = 4 GeV2)-0.04
-0.02
0
0.02
0.04
-0.04
-0.02
0
0.02
0.04
-0.04
-0.02
0
0.02
0.04
10 -2 10 -1 1
DSSVDSSV andEIC 5 GeV on 100 GeV& 5 GeV on 250 GeV
all uncertainties for !"2= 9x!u x!d
x!s
x
Q2 = 10 GeV2
x!g
x
-0.2
-0.1
-0
0.1
0.2
0.3
10 -2 10 -1 1
many newsmaller partonsare produced
Proton(x, Q2)
Proton(x0, Q2)
x0 >> x
Low Energy High Energy
parton
“Color Glass Condensate”
(FL -
FLlea
ding t
wist )/F
L
(FL -
FLlea
ding t
wist )/F
L
Au (A=197)proton
-5-4
-3 -21
23
-10
-8
-6
-4
-2
0
log10(x) log 10(Q2 )
log10(x) log 10(Q2 )-5
-4-3 -2
12
3-10
-8
-6
-4
-2
0
ABSTRACT An Electron-Ion Collider facility (EIC) [1], a project although known as eRHIC, is under consideration at the Brookhaven National Laboratory (BNL). eRHIC is a machine designed to collide an electron beam with the currently existing RHIC hadron beam (protons and nuclei), capable of largely varying the center-of-mass energy produced in the collision and the polarization of both beams. The use of a high energy electron beam, the high luminosity of the machine expected in the order of 1034 events/cm2 *s at the highest center-of-mass energy, and the new specifically designed detector, will make eRHIC the ideal “microscope” for investigating, with an unprecedented precision, the three-dimensional picture of the internal structure of the proton. Here I briefly review the most important topics of the broad physics case we aim to carry on at eRHIC and the large impact that such machine can have versus the current knowledge of quarks and gluons (the building blocks of the matter) and thus how they contribute to all the basic properties that characterize a single nucleon, such as mass, charge and spin.
Beam energies: Polarized electrons: 5 to 20 GeV Polarized protons: 100 to 250 GeV Ions: 50 to 100 GeV/nucleon
No other tunnel required: electron beam line will be added in the present
RHIC tunnel (cheep and green)
Up to 3 experimental locations along the ring
Very high luminosity 1034 events/cm2 *s (100 times higher than the
previous electron-proton collider: HERA)
Physics goals
Tomography of a nucleon/nucleus in three dimensions
Understand the properties of gluons, which dominate the mass and density of the visible matter in the Universe!
Determine quark and gluon contribution to the proton spin: solve the “spin puzzle”
Physics motivation
What is the space-time and momentum distribution of quarks and gluons in nucleons?
What is the role of strong gluon fluids and parton saturation effects in scattering of nuclei?
What is the polarization of gluons in the region where they are most abundant?
What is the flavor decomposition of the polarized sea-quarks?
Newly designed dedicated detector • Hermetic Central Tracking Detector • Good EM calorimeter resolution with fine granularity • Preshower electromagnetic calorimeter • Very forward calorimeter and proton spectrometer
3D picture in coordinate space 3D picture in momentum space
Result from the HERA Collider: whilst the valence quarks dominate at large x values (~0.3) for x < 10-‐1 the nucleon density is dominated by gluons
Gluon satura7on: when gluon density becomes large enough, small gluons are believed to combine together as described in the Color Glass Condensate (CGC) theory [3], but this state of the maJer to the present remains experimentally uninves.gated
References: [1] White Paper on the Electron Ion Collider – Available on-‐line:
http://skipper.physics.sunysb.edu/~abhay/eicwp12/draft/EIC-WhitePaper-11232012.pdf
[2] S. Fazio, T. Toll, and T. Burton – “eRHIC: An Ultra-‐High-‐Resolu7on Electron Femtoscope” http://www.bnl.gov/rhic/inside/news.asp?a=2465&t=today
[3] E. Iancu, A. Leonidov, and L. D. McLerran, Phys. LeJ. B510, 133 (2001)
[4] J. Bartels, K. Golec-‐Biernat, and L. Motyka, Phys. Rev. D81, 054017 (2010)
The x variable: known as “x of Bjorken” it is the frac7on of the total momentum of the nucleon carried by the parton (quark or gluon) par7cipa7ng in the interac7on
Parton densi,es
Access satura7on: eRHIC will be sensible to satura.on (e.g. in e+Au collisions) [1]. Figure shows the simulated measurement of the longitudinal structure func7on FL for both protons and Au at eRHIC, satura.on effects are much more prevalent in e+Au [4].
Gluon satura7on effects are expected to be higher in heavy nuclei
eRHIC will be an ideal to explore the satura7on regime!
What is the spin: In quantum mechanics, spin is the intrinsic angular momentum carried by a particle
Open question: How quarks and gluons contribute to the spin of the proton?
Goal: solve the “spin puzzle”
Open questions:
In a fast moving nucleon the longitudinal size squeezes like a “pizza” but transverse size remains about 1 fm
Can we resolve transverse coordinate or momentum space in a parton density picture?
Goal: nucleon tomography!
Electron Proton/Nucleus
Electron beams will be our microscope light, used to
investigate the structure of nucleons/nuclei
p
e
(Existing) (to be build)
Op7cal microscope
eRHIC
Paul C. Lauterbur
Sir Peter Mansfield
Nobel Prize, 2003: "for their discoveries concerning magnetic resonance imaging"
nucleon eRHIC
Tomography is today commonly used in hospitals
@ eRHIC we will do the same to nucleons and nuclei
The idea: building a large quantum “femto”-scope [2]...
ONLY at eRHIC ! Unlike LHC, eRHIC will polarize both electron and proton/nuclei beams and will extend of 1000 7mes the currently available x-‐Bjorken range available at fixed target experiments [1], allowing to solve the puzzle!
1980s 1990/2000s now
Valence quarks: contribute ~ 30%
60% ???
Gluons: RHIC suggest
~ 10%
Δg(x,Q2) = g (x,Q2)-‐g (x,Q2)
The predicted impact of eRHIC
Acknowledgements All my research on eRHIC is carried on as member of the BNL EIC Science Task Force – therefore I would like to thank all my collaborators: Elke Aschenauer, Thomas Ullrich, Thomas Burton, Ramiro Debbe, BenedeJo di Ruzza, Jamie Dunlop, Wlodek Guryn, MaJ Lamont, J. H. Lee, Dieter Mueller, Hubert Spiesberger, Marco Stratmann, Tobias Toll, Liang Zheng
Please visit our web-‐page: https://wiki.bnl.gov/eic/index.php/Main_Page
