# Presentation: 239655

## The Jet Target for RUN 4

- Yousef Makdisi
- On behalf of the Polarized Jet collaboration
- RSC meeting Feb 27, 2004
- Commissioning exercise
- Status
- Impact on the machine
- Installation
- Bring to operational status
- Polarization Measurements and Timelines

## Status

**Major construction on the jet was completed by mid October 2003.**
**The Jet was moved to RHIC and installed on its tracks in October 2003.**
**Operated remotely for a period of 3 weeks with all systems running.**
**Returned the Jet to the lab during the third week in November.**
**Some alignment efforts ensued (December 03)**
**Measurements of the H /H****2 ****/H****2****O were carried out. (January 04)**
**Improved the nozzle cooling. (February 04)**
**Connected supplies to VME for computer control (Jan and Feb 04)**
**Installed Test silicon detectors to assess H effects on leakage current / performance as was experienced at IUCF.**
**WFDs for p-Carbon and Jet delivered to BNL. (February 04)**
**Completed detector electronics design. (Feb 04) Fabrication (ongoing)**
**Remaining items:**
**Recoil collimators (within a week)**
**RF shield (within a week)**
**Software for automatic tuning  & polarization measurements**
**Final silicon detectors and electronics (2nd week in March)**

## Jet parameters

**The jet is running quite reliably with about 1.2 x 10****17**** atoms/ sec measured in the collision chamber.**
**The Jet beam profile is about 5.5 mm.**
**The Jet thickness as seen by the RHIC beam is 10****12**** atoms/cm****2****.**
**The molecular hydrogen background was measured at 3% nuclear.**
**The jet vacuum in the scattering chamber is 1x10****-8**** Torr with beam off and 2x10****-8**** Torr with jet beam on.**
**The RF transitions in both the ABS and BRP stages are operating at 99% efficiency.**
**Silicon detectors will be installed to measure one beam only.**

## Jet in the IR

- Three flanges to button up which will speed the leak checking process.
- Two valves on either side
- Beam pipe profile reduced from 5” diameter to a 6x6 cm2
- Copper RF shield across the jet to minimize RF impedance
- Vacuum at 2-5 x 10-9 Torr on either side of the jet allows a continuous operation.

## The impact of H-Jet to IP12 vacuum (Hseuh)

- Vacuum @ 1.3m
-     low e-10 Torr w/ valves closed
-     ~ 1e-9 Torr with Jet off
-     ~ 5e-9 Torr with Jet on
- Vacuum @ 7.5m
-     ~ 1e-11 Torr with Jet off
-     ~ 5e-11 Torr with Jet on
- P is mostly hydrogen @ 7.5m
- No observable increase in heavier species

- CO

- H**2**

- H**2**O

- O**2**

**12 hrs**

- RGA  Data

**20 hrs**

- g11-pwx

- g11-pwx.2

**g12-pwx.1**

## Install the Jet in the tunnel (March 24??)

**Estimate a 3-day shutdown on restricted access**
**Move the racks a day or two earlier to the 12 o'clock service building **
**Electrical and water systems will be connected.**
**Load the on a truck a day earlier and park overnight in building 912 awaiting the opening of the tunnel.**
**Rig the jet into the tunnel (1/2 day)            ****(The clock starts !!)**
**Install the jet on the tracks and survey (1 shift)**
**Connect services electrical, cabling, air, water cooling (parasitic)**
**Turn on the vacuum system and leak check (2 shifts)**
**Run the jet and get to a state where we are controlling it remotely (1day)**
**We will have continuous shift coverage to manage this stage**
**An additional day of contingency when we enter under Controlled access.**

## Bring the Jet to full operational status

**Estimate another 1/2-1 weeks to fine tune the jet beam parameters and attain a stable running condition. (Parasitic with RHIC beam tuning.)**
**Tune the dissociator for maximum intensity**
**Measure the intensity in chamber 7 by pressure rise**
**Turn on the holding field magnet, RF systems, and BRP gage and measure the jet polarization **_**without beam**_**.**
- Measurements in November indicated the jet beam polarization to be 99% of the theoretical maximum (this depends on the holding field magnet setting)
**Repeat the Jet polarization measurement **_**with beam**_ (dedicated - 1 shift?)
- Assess if we suffer any beam depolarization from the bunched beam (and intensity). Our expectation is no effect if running with 56 bunches. This has to do with the uniformity of the holding field magnet.
- It does not matter if the beam is at injection or at store. However, it is of interest to do the same with the 200 Mhz system on.
- The two RHIC beams should be separated by at least 1 cm horizontally.

## Silicon detectors

**      ****Estimate 1-2 weeks to fine tune the silicon detectors and readout. This partially overlaps with the jet tuning.**
**Adjust grounding to assure maximal signal to noise ratio (this may require entry to the IR)**
**Parasitically with beam on tune the silicon detectors to the elastic scattering process (timing and energy). **
**This can be done with a stored proton beam regardless of polarization or energy at injection or 100 GeV. The recoil proton energy and timing do not change drastically with energy.**
**At this point we will be in a position to start using the jet polarization and a polarized beam to measure the Analyzing power of pp elastic scattering in the CNI region.**
**We need a reliable mechanism to assure the beam is centered on the jet (BPMs and profile measurements)**

## Beam Polarization measurements

**We estimate 1 week of dedicated running with one "stable" polarized beam (Blue Ring) to gather the necessary statistics for a 10% measurement of the beam polarization. **
**We would like to collect 10M elastic events. **
****** ****= 3.10****-4**** and A****N ****= 0.03 ******** ********/A****N**** =.01 Using 1x10****11 ****per bunch, Jet density 2x10****12 ****atoms per cm****2****, this should take 24 hours. Assuming 50% accelerator up time and 50% detector efficiency, we are up to 4 days. **
**We will have target empty runs to assess the beam gas interactions.**
**Additional runs with different collimation.**
**Of course, the data will be collected with different jet polarization conditions.**
**Because of the common WFDs, data will be collected alternately with the respective p-Carbon CNI polarimeter in order to calibrate that polarimeter.  Several variations on this theme will be tried.**

## Banking on Success

**We will move to the Yellow RHIC beam. In this case the recoil silicon detectors are positioned in the backward region, thus another background type measurement. **
** ****We need to remotely translate the jet from one beam line to the other.**
**We would like to measure the effect of the bunched beam on the jet polarization with a 112-bunch fill.  This impacts the uniformity of the holding field magnet. (about 1 shift)**
**This is likely to overlap with plans to see what intensity per bunch and luminosity  the collider can achieve with such a fill.**
- An advertisement:
- A C-AD seminar on the Polarized Jet Target : Friday March 5th at 4 pm.
- By Alexander Nass