14T 8 15101530 ZelenskiA

Studies of atomic beam production in the H-jet polarimeter for RHIC.: 

Studies of atomic beam production in the H-jet polarimeter for RHIC. A.Zelenski, D.Graham, W.Haeberli, A.Kponou, G.Mahler, Y.Makdisi, A.Nass, J.Ritter, T.Wise, V.Zubets. SPIN 2004, Trieste Dissociator design and operation. Atomic beam intensity measurements and calibrations. Atomic beam profile measurements. 4. QMA-quadrupole mass analyzer upgrade. QMA calibration. 5. H2/ H – ratio measurements at the collision point. 6. Summary.

RHIC: the “Polarized” Collider: 

RHIC: the “Polarized” Collider BRAHMS & PP2PP STAR PHENIX AGS LINAC BOOSTER Pol. H- source Spin Rotators 20% Snake Siberian Snakes 200 MeV polarimeter AGS inelastic polarimeter Rf Dipoles RHIC pC “CNI” polarimeters PHOBOS RHIC Absolute H-jet polarimeter 70% Polarization Lmax = 2  1032 s-1cm-2 50 < Ös < 500 GeV AGS pC “CNI” polarimeter 5% Snake Polarization facilities at RHIC.

H-jet polarimeter setup at IP12.: 

H-jet polarimeter setup at IP12. Polarized H-jet target - 1.3·1012 at/cm2. Polarization ~ 93%. Event rate ; ~6Hz　(0.7~5MeV) 7cm 6cm FWHM 6.0 mm

Polarization measurements in RHIC with the polarized H-jet. : 

Polarization measurements in RHIC with the polarized H-jet. PT APP PB ApC PB – beam polarization Exp.asymm.(pp) 22-250 GeV beam energy. ± 5% absolute accuracy. Analyzing power meas. Exp.asymm.(pC) Measured to ±1% accuracy by the BRP.

H-JET POLARIMETER SCATTERING CHAMBER.: 

H-JET POLARIMETER SCATTERING CHAMBER. ~80 cm

The absolute proton polarimeter H-jet at IP-12: 

The absolute proton polarimeter H-jet at IP-12 Polarized H-jet target thickness of (1.3+/-0.2)· 1012 H/cm2 Polarization 93 +1/-2 % . Silicon recoil spectrometer.

Polarimeter vacuum system.: 

Polarimeter vacuum system. The H-jet polarimeter includes three major parts: polarized Atomic Beam Source (ABS), scattering chamber, and Breit-Rabi polarimeter. The polarimeter axis is vertical and the recoil protons are detected in the horizontal plane. The common vacuum system is assembled from nine identical vacuum chambers, which provide nine stages of differential pumping. The system building block is a cylindrical vacuum chamber 50 cm in diameter and of 32 cm length with the four 20 cm (8.0”) ID pumping ports. 19 TMP , 1000 l/s pumping speed for hydrogen.

H-jet vacuum system.: 

H-jet vacuum system. Total height 350 cm. Total weight ~3000 kg . The whole polarimeter is movable +/-10 mm in horizontal direction. 4 roughing lines, pumped by oil- free Leybold EcoDry-15. 1st-Ch.1,vac.~1.0 torr; 2nd-Ch.2,vac. ~ 60 mtorr; 3rd-Ch.3,4,5,6,7, vac.~ 30 mtorr; 4th-Ch.8,9, vac.~ 25 mtorr. 1.9 ·10-4 9.5 ·10-6 2.2 ·10-6 3.8 ·10-7 1.7 ·10-7 2.4 ·10-8 2.0 ·10-7 9.7 ·10-8 1.7 ·10-8 19, V1000HT-pumps are mounted horizontally.

H-jet polarimeter can be moved and installed into the RHIC ring in one day.: 

H-jet polarimeter can be moved and installed into the RHIC ring in one day. The power supply and control system is assembled in seven joint racks on the wheels.

H-jet layout at the IP-12.: 

H-jet layout at the IP-12. 200 cm in between RHIC isolation valves. 10-8 torr 10-9 torr

Vacuum spikes at the IP-12 during high intensity beam injection .: 

Vacuum spikes at the IP-12 during high intensity beam injection . Beam intensity in RHIC 10-8 torr Vacuum spikes during injection cycle is similar to other IPs.

Slide12: 

H-jet dissociator. Nozzle, 75 K. RF-cavity Neck, 140 K Top flange, 195 K

H-jet dissociator design.: 

H-jet dissociator design. 65 cm Cooling multifoil copper straps. Window. Cold head, 42 K

Movable skimmer baffle.: 

Movable skimmer baffle. Driving worm-type gears allow +/-10 mm skimmer postion ajustment for the ABS intensity optimization. Optimal nozzle to skimmer distance is 15 mm, skimmer to 6-pole magnet distance is 40 mm.

H-jet sextupole separation magnet system.: 

H-jet sextupole separation magnet system. 24 sectors separating magnets with 1.5 T field at the pole tips.

Simulations of the 6-pole separating magnet system.: 

Simulations of the 6-pole separating magnet system. Collision point. BR-polarimeter, 125 cm ABS, 140 cm Atoms with mJ=+1/2 trajectories.

Compression tube calibration.: 

Compression tube calibration. Hydrogen mass-flow controller MKS. Full range: 0.0-1.0 scc/min. Absolute accuracy 1-2%. Conventional technique: pressure drop in calibrated volume. Independent AB intensity measurement from the well known TMP pumping speed. H0 H2 Hot filament ion gage. Ø -10 mm. Length-10 cm

The compression tube calibration system for the absolute AB intensity measurements.: 

The compression tube calibration system for the absolute AB intensity measurements. H-beam Ion gage Ion gage H2 mass-flow controller and a pressure drop measurement in the calibrated volume were used for compression tube calibration.

Atomic beam intensity dependence vs. H2 flow in dissociator.: 

Atomic beam intensity dependence vs. H2 flow in dissociator. AB intensity at 65 scc/s H2 flow and O2 flow of a 0.2 sccm is 12.5·1016 at/s.

AB intensity vs. nozzle temperature.: 

AB intensity vs. nozzle temperature. The maximum AB intensity was measured at Tnozzle =75 K . 12.5+/-0.2 1016 atoms/s

Operational atomic beam sources intensities.: 

Operational atomic beam sources intensities. H-jet 12.5·1016 at/s Maximum H-jet beam intensity is at Tnozzle~75 K. H-jet design HERMES ANKE, COSY PINTEX, IUCF FILTEX ANKE, first results

Compression tube for the AB profile measurements. : 

Compression tube for the AB profile measurements. Ø 2.0 mm collimator.

Slide23: 

FWHM 5.0 mm

Atomic beam intensity profile measurements.: 

Atomic beam intensity profile measurements. Beam profile at the entrance of 6-pole #5. Beam profile at the RHIC beam collision point.

H-jet target intensity profile at the RHIC collision point.: 

H-jet target intensity profile at the RHIC collision point. Horizontal position of the JET ,10000 steps = 2.5 mm. FWHM ~ 6.0 mm in agreement with a compression tube measurements. Number of elastic pp events Profile was measured from elastic pp scattering events.

QMA upgrade for H-jet measurements.: 

QMA upgrade for H-jet measurements. Original QMA geometry (right) Expanded QMA sensitive volume (left) 10 mm

Atomic beam intensity and density measurements in the collision region.: 

Atomic beam intensity and density measurements in the collision region. H-beam intensity and density vs. H2 flow in dissociator.

H-jet operation April 6 – May 14, 2004: 

H-jet operation April 6 – May 14, 2004 May 6-16 Apr.13 Apr.21-22 Apr.28 May 2

H-jet performance in 2004 run at RHIC.: 

H-jet performance in 2004 run at RHIC. Overall H-jet operation was reliable in the first Apri-May 2004 run at RHIC. The atomic beam intensity was stable. The dissociator required maintanance about once a week. The first beam velocity measurements gives: V~ (1.6-1.8)·105 cm/s. The total H-jet thickness is about 1.3·1012 atoms/cm2. H2/H~1.5% -ratio was measured in the collision region with the QMA, which gives about 3% polarization dilution. It gives 93+1/-2 % effective proton polarization at 1.2 kG holding field and 94 1.5% polarization at 1.4 kG field.

Summary of 2004 H-jet polarimeter operation.: 

Summary of 2004 H-jet polarimeter operation. Clean recoil proton signals were detected at Erecoil =1-2 MeV. Total number of events in 1-2 MeV range is ~1.2 ·106 at 100 GeV beam energy and 0.14·106 at 24 GeV beam energy. The analyzing power An for pp scattering at 100 GeV was measured to ± 6 % statistical accuracy. Proton beam polarization averaged over about 100 hrs data taking was measured to ± 8% statistical accuracy. H-jet gives the best polarization scaling factor for collision experiments. H-jet doesn’t affect the RHIC operation and there is a plan to operate the H-jet polarimeter continuously during the polarized runs.

Atomic beam trajectories in BRP with both SFT and WFT –transitions are “on”.: 

Atomic beam trajectories in BRP with both SFT and WFT –transitions are “on”. BRP gage. RF-transitions 6-pole BRP magnets Beam chopper Collision point

QMA calibration.: 

QMA calibration. QMA atomic beam signal vs. H2 partial gas pressure in the collision chamber. 10-7 torr.H2  0.98· 10 10 H2/cm3 Measured H2 / H density ratio: ~1.5%× 2  3%-polarization dilution.