# Presentation: 442313

## Status of polarized ion source.

- Summary of 2004 run.
- OPPIS upgrade for 2005 run.

- A.Zelenski

## Polarized injector, 200 MeV linac and injection lines.

- OPPIS

- 200 MeV polarimeter

- Polarization direction is adjusted vertically in the 750 keV beamline by the solenoidal spin -rotator.

## SCHEMATIC LAYOUT OF THE RHIC OPPIS.

- 28 GHz ECR
-  proton source

- Rb cell

- SCS solenoid

- Probe
- laser

- Na-jet
- Ionizer
- cell

- Pumping
- laser

- Cryopumps

## 200 MeV p-Carbon and p-D polarimeter.

- 12 deg proton arms.

- D-recoil arms

## 200 MeV polarization measurements.

- Sequential measurements.

- 80%

- Polarization histogramm,
- maximum at 82%.

- 82%

## Polarization measurements fluctuations due to beam position “wondering” at the target. 

- 80 %

## H- ion beam current and polarization vs. optically-pumped 
Rb vapor thickness.

- Rb vapor thickness.

- 2.0 mA H-
- Current
- P=85%
- Pulsed
- laser

- DC laser
- optical
- pumping

- Polarization measurements at 300 keV at TRIUMF.

## The Oxford Instr. superconducting solenoid at TRIUMF OPPIS.

- The solenoid has the cold yoke (lower transversal field).
- The field is more homogeneous and better confined.
- The solenoid had been shipped to BNL and will be installed for the 2005 run.

## Upgrade status.

- The TRIUMF OPPIS superconducting solenoid had been shipped to BNL.
- At BNL in preparation for the solenoid arrival the operational OPPIS was completely refurbished.
- New support frame, a Na-jet ionizer power supply system was completely rebuilt, a new plumbing and wiring, realignment.
- At present, the source is back into operation with the old solenoid. A new solenoid will be initially assembled and fully tested at the separate test-bench.

## A source layout at the new test bench and the  Oxford Instr. solenoid. 

- 29 GHz
- PS

- Na-jet ionizer PS,
-  biased to 32 kV.

- SCS, 24.5 kG

- Probe laser

## Conclusions.

- BNL OPPIS very reliably delivers polarized H- ion beam (P = 80%) for the RHIC spin program.
- A beam intensity exceeds RHIC limit, which allowed strong beam collimation in the Booster, to reduce longitudinal and transverse beam emittances.
-   The TRIUMF OPPIS  superconducting solenoid (Oxford Instr.) was purchased  to improve beam intensity and increase polarization to 85% value.
- This should provide sufficient intensity and higher polarization for the planned RHIC luminosity increase in run 2005.

##  H-jet polarimeter.

- _A.Zelenski,_ D.Graham, W.Haeberli, A.Kponou, G.Mahler,
- Y.Makdisi, A.Nass, J.Ritter, T.Wise, V.Zubets.

- RSC meeting, Torino, October 8, 2004

- 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.

## Set up @ IP12

- 2.5mm

- Target profile
- FWHM ~ 5mm

**Polarized Hydrogen Gas Jet Target **
**     ****polarization    0.924 +/- 0.018 **

**Si detector**
** ****7cm * 6cm  / detector, 3 pairs**
** ****Acceptance 2****π****/16**
**Measurement**** ****( recoil particle )**
**   **** ****energy  **
**       **** ****(0.7~7MeV res. < 50 keV)**
**   **** ****TOF ****(70~16ns res. < 2 ns)**
**   **** ****Angle****(10~100****  mrad ,**
**               ****res. <5mrad)**

- Event rate ;  ~6Hz (0.7~5MeV)

- 7cm

- 6cm

## H-JET POLARIMETER SCATTERING CHAMBER

## The absolute proton polarimeter.

**H-JET in the IR-12**

- Polarized H- jet Target
- Thickness :  1.3+/-0.2 ·1012 p/cm2
-  Polarization:    93%

## 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.

## 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.

## IR 12-vacuum schematic diagram

- Pwx2.11

- Pwx2.12

**H-jet**

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

## H-jet dissociator.

- Nozzle.

- RF-cavity

## H-jet dissociator design.

- 65 cm

- Cooling multifoil copper straps.

## 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.

**24 sectors separating**
**magnets with 1.5 T field**
** ****at the pole tips.**

## 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.

- 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.

- 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 on H2 flow in dissociator.

**AB intensity at**
**65 scc/s H****2**** flow is  12.5****·****10****16**** at/s.**

## AB intensity vs. nozzle temperature.

**The maximum AB intensity was measured at **
**T****nozzle**** =75 deg. K**

- 12.5+/-0.2 1016 atoms/s

## Operational atomic beam sources for polarized target applications.

- HERMES- at DESY, Hamburg
- PINTEX-  at IUCF, Indiana (moved to IFNF, Italy)
- Cryogenic ABS - Novosibirsk
- EDDA -    COSY, Julich
- ANKE  - COSY,  Julich
- BLAST – MIT, Bates
- H-jet polarimeter – BNL, New-York
- There are about 20 operational polarized ion sources based on atomic beam technique. All around the world.

## Operational atomic beam sources intensities.

**H-jet**
**12.5****·****10****16**** at/s**

- Maximum H-jet
- beam intensity is at
- Tnozzle~75 deg. K

- T.Wise calc.

- HERMES

- ANKE, COSY

## Compression tube for the AB profile measurements. 

- Ø 2 mm collimator.

**FWHM**
**5.0 ****mm**

## 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.

- Hor. position of the JET ,10000 steps = 2.5 mm.

-  FWHM ~ 6 mm
-  in agreement with a compression tube
-  measurements.

- Number of elastic *pp* events

- Profile was measured from elastic *pp* scattering events.

## 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

## RF-transition operation.  Atomic beam polarization reversal.

## Efficiencies and nuclear polarization.

- Stable behaviour over the whole 2004 run, mean values for nuclear polarization of the atoms:
- P+ = 0.9570.001 and Pˉ = -0.9590.001. More deatails in A.Nass talk.

## Stability of nuclear polarization.

## QMA upgrade for H-jet measurements.

- Original QMA geometry (right).
- Expanded QMA sensitive volume (left).

- 10 mm

## Time –of - flight beam velocity and velocity spread measurements out of dissociator

- QMA

- Beam chopper

- 69 cm

- ABS separating magnets were removed for these measurements.

- The narrow velocity spread is expected from the H-jet dissociator (due to long cooling “neck”), which can be a significant factor in the superior H-jet performance.

## QMA atomic beam velocity measurements.

- 0.9 ms

**L=135 cm- drift length.**

- Tn=80°

- Tn=60°

- Tn=90°

**Vb ****~1500-1800 m/s**

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

- H-beam intensity and density vs. H2 flow in dissociator.

## QMA calibration.

**QMA atomic beam signal vs. H****2**** partial gas pressure in the collision chamber.**

**10****-7**** torr.H****2**** ******
**0.98****·**** ****10 ****10**** H****2****/cm3**

**Measured H****2**** / H  density ratio:**
** ****~****1.5%****× ****2 ******** 3%-polarization dilution.**

## Optical diagnostics for atomic and molecular hydrogen components.

- PM

- Filter,650nm

- Lenses

## H/H2 –measurements with the magnetic analyzer. T.Wise.

- Electron gun

- FC

- Analyzing magnet

- Extraction optics

## 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.

- 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~ (1.6-1.9)·105 cm/s. The total H-jet thickness is about  1.3·1012 atoms/cm2.
- The RF-transitions efficiencies were measured with BRP polarimeter at  ~ 99.9%. SFT turn-on time has to be reduced.
- 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% polarization at 1.4 kG field.

##     Problems.
     Turbopump failures.
Frequent dissociator maintenance.

Plans.
Improve dissociator operation stability and lifetime between services. (Additional heater attached to the cold head reduced the maintenance time from 8 to 3 hrs).
Measure atomic beam velocity to get a better accuracy for the target thickness.
Develop diagnostics devices for molecular hydrogen component measurements. 
Design and build  shutters for the r/a  calibration sources.

-      Turbopump failures.
- Frequent dissociator maintenance.
- Plans.
- Improve dissociator operation stability and lifetime between services. (Additional heater attached to the cold head reduced the maintenance time from 8 to 3 hrs).
- Measure atomic beam velocity to get a better accuracy for the target thickness.
- Develop diagnostics devices for molecular hydrogen component measurements.
- Design and build  shutters for the r/a  calibration sources.