DIS and SIDIS measurements with BigBite & Super Bigbite Spectrometer and 11 GeV beam in Hall A

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1 DIS and SIDIS measurements with BigBite & Super Bigbite Spectrometer and 11 GeV beam in Hall A B. Wojtsekhowski, JLab 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 1

2 One- and Two-Arm experiments (O&TA) Most productive experiments in the field are belong to the category O&TA: among them are DIS, SIDIS, FFs (GEP), RCS, DVCS,... Everything in A/C sections of 12 GeV CDR fall into O&TA Main advantage of the (e,e ) & (e,e h/γ) is simplicity of such processes, very different than in N*+. F OM = L Ω 1 ( Ω 2 )

3 Figure-of-Merit for O&TA experiments One-arm experiments: high L and large Ω (ΔQ 2 /Q 2 ~ 0.1) : Super Bigbite Spectrometer is the best due to Ω = 70 msr Two-arm experiments are dealing with elastic or quasi-elastic p m ~ 0.2 GeV/c for the nuclei; ~ GeV/c for the nucleon High Q 2 /t/ν experiment means for the hadron p h ~ 2-8 GeV/c; 70 msr of SBS acceptance, detector captures efficiently events up to p m ~ p/5 => one setting could be a whole experiment F OM = L Ω electron = electron nucleon sr Hz/cm 2

4 Concept considerations of Super Bigbite Vertical bending > use the beam coordinate Detector located behind the magnetic field Compact beam spot on the target Simple dipole for large acceptance Field integral and detector resolution Forward angles vs. solid angle 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 4

5 Magnet conceptual design View to A! A Right yoke Beam Field on beam line Right yoke A Beam line opening A 146" 200 G 0 Left coil Right coil 92" ~ 100 G x 50 cm Target 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 5

6 SBS physics program GEp : reach unique high 14.5 (GeV/c) 2 approved GMn: reach absolute max 18 (GeV/c) 2 approved GEn : reach full glory with 10 (GeV/c) 2 approved SSA in nsidis: 30,000 gain vs HERMES cond. approved =========================================== A1n/d2n now has gain of 30 vs Hall C, approved for BigBite A1p/d2p with best experimental setup D(e,e d) -- event rate gain ~ 50 at 6 (GeV/c) 2 T/ 3 He(e,e ) : 0.1 g of T in the target = 0.6% of Bates RCS s ~ 22 GeV 2 dσ/dt, K LL, A LL PVDIS gain compare with two HRSs A(e,e φ) - large program including DIS, pol.target, exclusive H(e,e π + n) recoil polarization in kinematics => F π

7 Physics program: inclusive Inclusive electron scattering: high x ( ); u/d; pol. u;d; T/He-3 (e,e ) ; double pol. 3 He(e,e ); ND 3 (e,e ); NH 3 (e,e ) Solid angle; momentum acceptance, luminosity msr 100%; max available up to 1 x10 38 ======================================================================== A1n experiment will have FOM about 5000 higher than was done with HRS G.Cates projects: 3 He target with P=60%, L=10 38 Hz/cm 2 event rate will be of 10 khz / 10% of (dp/p) compare this with best A1n ~ P=35%, L=10 36 Hz/cm 2

8 Cates, Liyanage, Meziani, Rosner, Zheng, and BW Polarized DIS with SBS Liyanage for beam time of 1000 hours GEM tracker SBS advantage over HMS+SHMS ~ 12 SBS advantage over BigBite ~ 6 very good accuracy, x up to 0.75 first test of Q 2 dependence 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 8

9 The SSA of SIDIS processes n (e,e π ± )X and n (e,e K ± )X Extract Sivers and Collins (and Pretzelosity) asymmetries on π and K with high statistics Provide 2D binning (at least) on the relevant variables: x, P and z, for both hadrons Provide Q 2 dependence Cates, Cisbani, Franklin and BW Explore for the first time the high x valence region (with overlap to HERMES, COMPASS, JLab6 data) Understand QCD dynamics in the nucleon by the Sivers effect Improve knowledge of the nucleon structure in terms of parton distribution functions Shed more light on the origin of the nucleon spin 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 9

10 Method: from SIDIS to SSA to DF FF Pretzelosity 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 10

2!sin("-" S )# h UT 2!sin("-" S )# h UT 0.25 0.2 0.15 0.1 0.05 0 0.15 0.1 0.05 0-0.05-0.1-0.15 Sivers Moments on proton/deuteron K + $ + K - $ - 0.1 0.2 0.3 HERMES PRELIMINARY III 2002-2005 lepton beam asymmetry, Sivers amplitudes 8.

11 2!sin("-" S )# h UT 2!sin("-" S )# h UT Sivers Moments on proton/deuteron K + $ + K - $ HERMES PRELIMINARY III lepton beam asymmetry, Sivers amplitudes 8.1% scale uncertainty x z P h% [GeV] From Levorato / Transversity 2008 From Pappalardo / Transversity 2008 COMPASS/deuteron Proton (left) K+ twice π+ conflict with u dominance expectation K- and π- consistent with 0 COMPASS smaller than HERMES Deuteron (up): consistent with 0, expected asymmetry on neutron as large as on proton Hepex Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 11

12 Experimental Setup and parameters e+ 3 He e +π(k) ± +X DOE DOE DOE Beam: 50 µa, E=8.8 and 11 GeV (80% long. Pol.) Target: 65% polarized 3He GEn(2)/PR Luminosity: cm -2 s -1, 50 msr DOE BB: e-arm at 30 o Ω = 45 msr GEM Tracker Gas Cherenkov Shower GMn/E SBS: h-arm at 14 o Ω = 50 msr GEM tracker excellent PID / RICH Hadron CALO Event rate: ~10 4 HERMES 60 days of production expected stat. accuracy: 1/10 of proton HERMES 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 12

13 SIDIS phi-acceptance SBS h BB P e (deg) phi s (deg) h phi ! = 30! = 24 " =14 " = 30 (deg) phi h +phi s theta qp phi h -phi s (deg) theta qp theta qp theta qp 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 13

14 SIDIS phi-acceptance P (deg) phi s (deg) h phi h e ! = 30! = 24 " =14 " = 30 (deg) phi h +phi s theta qp phi h -phi s (deg) theta qp theta qp theta qp 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 14

Azimuthal Coverage 0.4 0.2 0.55<x<0.65 0-3 -2-1 0 1 1 Partial coverage of φ h but in sin/cos sensible regions φ h 0.15 < x <0.65 ϑ h_cent.

15 Azimuthal Coverage <x< Partial coverage of φ h but in sin/cos sensible regions φ h 0.15 < x <0.65 ϑ h_cent. = 14 E beam = 11 GeV 4 target spin directions Complete coverage of the Collins, Sivers and Pretzelosity azimuthal angles with 4 target spin directions (with 8 target spin directions even better uniformity) 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 15

directions can be increased to have a better uniformity; 8 would

16 Azimuthal angles coverage vs x Azimuthal angles coverage does not very significantly depend on x,q 2 Number of target spin directions can be increased to have a better uniformity; 8 would be optimal in this respect. 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 16

Q 8 6 Q 2 coverage Prop. Exp. E beam = 11.0 GeV 4 2 Prop. Exp. E beam = 8.8 GeV Current Transversity Exp. E06-010 0.1 0.2 0.3 0.4 0.

17 Q 8 6 Q 2 coverage Prop. Exp. E beam = 11.0 GeV 4 2 Prop. Exp. E beam = 8.8 GeV Current Transversity Exp. E We will investigate the Q 2 dependence of the Sivers and Collins functions, with overlap in the region of HERMES; reveal higher twist effects. Analysis of the Q 2 effect will use also the results of presently running 6 GeV E Transversity experiment 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 17

18 Figure of Merit Two beam energy runs for Q 2 dependence studies: 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 18

19 What is special in our experiment? High Luminosity: 10 5 larger than in HERMES High target polarization (65%) Fast target polarization switch (120 seconds) 4 (8) transverse polarization directions Use of SBS (and BB): Large solid angle (50 msr), very good angular and vertex resolutions Large momentum coverage (2-7 GeV/c) Excellent hadron PID Reuse equipment from three FF s experiments: GEp(5), GEn(2) and GMn 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 19

20 Angular Resolution: σ ϑ_h = /p [mrad] Hadron Arm: SBS - Magnet: 48D48-46 cm gap 2 Tm field integral -100 ton Insert for beam pipe GEM chambers for tracking with 70 µm resolution HERMES RICH for hadron-id Segmented Hadron CALO (15x15 cm 2 blocks) (p = 4 GeV) (0.3 mrad) σ ϑ_v = /p [mrad] (0.4 mrad) Vertex Resolution: /p [mm] (0.2 cm/sinϑ central ) Momentum resolution σ p /p = 0.03 p+0.29 % (0.4 %) CALO Trigger Threshold: 1.5 GeV (online), 2.0 (offline) 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 20

6 GeV e- Very stable performance (δn/(naerogel-1)= 1%, 9 years) Stored at

21 Hadron PID: HERMES RICH on SBS 5.5 GeV K+ C4F10 gas REAL DATA from NIMA 479 (2002) GeV π GeV e- Very stable performance (δn/(naerogel-1)= 1%, 9 years) Stored at UVa under safe/controlled conditions (also additional wall of spare Aerogel) 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 21

22 Polarized He-3 Target Electron Laser light arm Polarized beam Target chamber Rb + K Recoiled neutron Pumping chamber Target Scattered electron Polarization pumping Neutron arm arm J polarized nuclei. x P 2 nuclei G E n 50 Polarization (%) Time (days) 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 22

23 High Lumi polarized He-3 Target Exclusive Reactions, 2002, Perspective for GEn, BW beam T1 Pumping cell He T2 > T1 gas flow Traditional target New target 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 23

!! beam T1 Pumping cell He T2 > T1 gas flow glass gold-plated metal New target 50 cm

24 High Lumi polarized He-3 Target Exclusive Reactions, 2002, Perspective for Gen, BW Convection idea is now tested and works!!! beam T1 Pumping cell He T2 > T1 gas flow glass gold-plated metal New target 50 cm Mixing times in current cells are minutes. Mixing times in convection cells can be around one minute. 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 24

25 High Lumi polarized He-3 Target 60% transverse polarization Support 60 µa beam current Extended target cell (60 cm) Proved alkali-hybrid mixture technique for polarization transfer Line-narrowed high-power diode-laser arrays Convection for gas mixing between target and pumping chambers The metal target cell 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 25

26 Summary We will measure the SSA in the transversely polarized SIDIS processes: n (e,e π ± )X and n (e,e K ± )X for large x at two Q 2 Will plan to take data in 2015 in two-month run. Experiment require no significant extra costs respect to SBS apparatus for GEp(5) 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 26

27 Background Rate and Trigger Logic BB-Shower (1 GeV): 200 khz 40 ns coinc./segmented accidental: 4 khz DIS-e: 1 khz BB-Offline / Tracking π 0 suppression: 1 khz Signal = 67 Hz BB-Cherenkov (3-4 pe): 2.5 MHz SBS-HCalo (1.5 GeV): 3 MHz Online 50 ns coinc. real coinc: 100 Hz acc: 750 Hz 4 ns time gate Total: 12 Hz Vertex Correlation (6σ=3 cm): 0.6 Hz Momentum cut > 2GeV Bck = 0.3 Hz Rate (khz) SBS Background on HCALO Particle Energy (GeV) Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 27

detector (2000 PMTs) is the optimal solution: Expected 35 extra hits/event from: soft photons Compton electrons in

28 Challenges in large acceptance/high luminosity SBS Tracker rate 60 khz/cm 2 ; 3xGEM support rate >10 MHz/cm 2 Track reconstruction: BB first, SBS from vertex to segmented HCALO hit RICH PID: high segmentation of photon detector (2000 PMTs) is the optimal solution: Expected 35 extra hits/event from: soft photons Compton electrons in aerogel (50 ns gate width) 2-5% occupancy ~20% of the HERMES RICH PMT array 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 28

29 Expected Statistical Accuracy on π Contalbrigo/SPIN bins (0.15<x<0.65, 0.2<z<0.7) (only one shown) High x region, with partial overlap with HERMES 2D binning in (x,z), (x,p ) and (z,p ) for π and K and Q 2 dependence DF from CTEQ5M FF from DSS 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 29

Expected Statistical Accuracy on K Superior quality of Kaon data Extend at higher x with partial overlap with existing data on proton, deuteron and

30 Expected Statistical Accuracy on K Superior quality of Kaon data Extend at higher x with partial overlap with existing data on proton, deuteron and expected results of HallA Transversity 6 GeV DF from CTEQ5M FF from DSS Rate normalized to HERMES/p+d K production 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 30

31 Physics Effects: Systematics FSI on nuclei 3He: P p ~2%, Ψ d 2 ~10%, P resc ~10-20% D: P p ~85%, Ψ d 2 ~6%, P resc ~5-10% Higher Twist Terms of SIDIS asymmetries Experimental/Analysis: Random background Vector Meson Particle ID Acceptance Effects Radiative Corrections 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 31

32 Polarized SI-DIS process 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 32

33 Phase Spase of the Relevant Variables Ebeam = 11 GeV 23 Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 33

34 φ h coverage vs x <x< sin/cos functions φ h Partial coverage of one (or both) azimuthal variables. When sinφ or cosφ (or φ S ) are close to 0 (red band) the AUT equation degenerates into the sum or difference of A C and A S. The variation of φ S is helpless. In all other case, even with partial coverage of φ and φ S the extraction of the two modulated terms is possible. Error on the extraction roughly goes like (coverage_fraction) -½ Sep 2009 B. Wojtsekhowski INT 12 GeV JLab 34

Progress of new spectrometer for Hall A

Progress of new spectrometer for Hall A Bogdan Wojtsekhowski, JLab for the SBB collaboration A concept Proton Form Factors ratio Key new detectors Organizational Structure Group meeting on 5/8/08 Multi