POLARIMERTY STATUS REPORT FOR RUN-11

November 18, 2010 RSC meerting

I. Alekseevb, E. Aschenauera, G. Atoiana, A. Bazilevskya, A. Diona,H. Huanga, Y. Makdisia, A. Poblagueva, W. Schmidkea, D. Smirnova,

D. Sviridab, K. Yipa, A. Zelenskia

aBrookhaven National Laboratory, Upton, NY 11973, USAbITEP, Moscow, Russia

Welcome Aboard!● Alan Dion (Physics)

– The Jet off line reconstruction programs will look at the various runs to reconcile differences. Documentation!

● Dmitri Smirnov (Physics)

– The p-C polarimeter fast off line programs, streamline and improvements and, a fresh look at the analysis. Documentation!

● Bill Schmidke (Physics)

– To lead the overall polarimetry effort, in training for now!!

● Andrei Poblaguev (C-AD)

– Complete the AGS studies, Online Jet programs and data analysis (take over for R. Gill) testing and Documentation!

● Grigor Atoian (An Old Hand) Physics > C-AD● Detector Ceramic design and testing

The Mission for RHIC

The polarimeters should operate over a wide range, beam energy from injection at 24 to 250 GeV

The physics program requires precision polarimetry < 5%

Polarimeter calibration is required at each energy

Beam polarization profile

Polarization lifetime or decay during a store

Polarization measurement on the ramp

Bunch to bunch emittance measurements

pp and p-Carbon Elastic Scattering

recoil p

polarizedp beam

scattered

proton

NN

NN

targetNtarget

beamNbeam

PA

PA

targettarget

beambeam PP

For p-p elastic scattering only:

elastic kinematics are fully constrained by the recoils only !0.001 < |t| < 0.02 (GeV/c)2

recoilproton or carbon

• Recoil carbons detected with Si detectors

• Identified via ToF vs Tkin correlation

inv. mass recoil =>gives only “particle ID”

• Position vs energy correlation spoiled by multiple scattering in target

• Background from beam dissociation very small for this kinematics

• Background events < few % within the “banana” cut

• very high event rate (> 105 ev/sec/ch)

CNI Polarimeter Principle Tkin = ½ MR (dist / ToF)2

non-relativistic kinematics

C

MR ~ 11 GeV

~ 1.5 GeV

MR

C*

AN ~1%: for 100% polarization

The Experience With the Polarimeters in Run9● Unstable polarization measurements at

250GeV due to serious rate problem.

● Full Ramp measurement did not work

Had to revert to measurements on the ramp above 100 GeV

● A few Wave Form Digitizers (WFD) not tuned properly when replaced during the run

● Larger target size than before

● Large increases in leakage current

(> 4μA)● Poor Energy resolution (>50 KeV)● “Dead layer” instability during run● Noise pick up due to long distance

(~100m) between Preamp and Shaper

AGS test for solutions(s)

Work on ramp measurement software

Experts on-site or knowledge transferred

Better QA and develop other technology

Continue the R&D

AGS Tests to Emulate RHIC Conditions

● In general the AGS runs in a single bunch mode with intensities up to 2x1011 per bunch

● 12 bunch pattern 1.5• 1011 per bunch at least 9 positions filled (bunch spacing is 240 nsec compared to RHIC 114 nsec)

● Push the single bunch intensity to as high as possible even if we run with unpolarized beam

● Targets 10 to 30 times thicker than at RHIC at

75, 125, and 600 microns

Using The AGS as a Test Bed

Two parallel efforts:

1)Replace the string: BNL Si detectors with Hamamtsu; front end electronics by

a VME based preamplifier and shaper board; WFD by ADC and TDC

2)Replace only the preamplifier by a current sensitive one

Charge Sensitive Preamplifier

Test Setup in the AGS

315ft cable, longer than 270ft in RHIC

Current Sensitive Amplifiers Bench Test with 10mm Special Cable Svirida

Bench Test with Usual Cable

Effect of the long cables

A Snapshot Of What The Detectors See As RateAlekseev and Svirida

Rate Problem in Run9 and Solution

Run9, s=500 GeV: METoF2 vs Rate (kHz/strip)

AGS tests, Mar 2010

Problems reproduced at AGS in Run 2010

No problems with new FEE (faster amplifiers)

New amplifierOld amplifier

0.1 s10 s

Unfinished Business with This Setup

• The parameters T0 and “dead layer” are important to the polarization determination. They are inconsistent between two methods.

• Added an extension pipe to resolve it. No conclusion from the data analysis yet. Will continue this test in the AGS.

• Putting a regular PC inside the AGS was risky: could not reset it after long (weeks) idle time. We will use solid state pc instead for the future.

• With all electronics outside will get deteriorated signals (lower amplitude, longer pulse)

• At RHIC for Run 11, a compromise half in / half out. But will be ready for the whole system to go either way.

16

Another Test w/New Detectors & Front End ElectronicsAnother Test w/New Detectors & Front End ElectronicsMorozovMorozov

Detectors:Hamamtsu Single PIN photodiode for direct detectionEach detector has 30mm x 3mm active area and ~300 μm thickness and placed along the beam axis.8 detector strips/per port placed at(+/- 45°) vacuum ports.

Front End:Charge sensing Preamps/Shapers (MSI-8 & MSCF-16) connected to the detectors through the 0.5 m long low capacitance coax.

The Shaper has two outputs:Digital (Time,CFD) – min delay 5ns with CFD –Walk: for 30ns input risetime, max 1ns (dynamic range 100:1)Dynamic range: - 33 MeV

Shaper has remote control capability.

Ultra thin Carbon ribbon Target(5g/cm2)

11

3344

55

66

22

12 Si-strips 12 Si-strips DetectorsDetectorsWith WFD With WFD readoutreadout

32cm32cm

8 Si PIN detectors8 Si PIN detectorsTest setupTest setup

Target axis

Beam axis

17

Beam Test

• No rate problem seen during the stress test.• Energy threshold could be as low as 100 KeV. (much lower at higher AN)• Asymmetries consistent with the old setup except when the old system has rate problem• The total background level ~ 12% (excluding prompts)• Asymmetry measurement in scalar mode due to RF noise due ground loop. • Redesigned the ceramic board with better grounding, change connectors, modify the feed through, and better RF shielding on the outside.

Clean Carbon Signals and Asymmetry Seen

Target Production

• After last run, an examination of the mask used to produce targets showed significant deterioration over repeated use. That was the direct reason for wider targets produced.

• Using new masks resulted in smaller targets as expected.

• We completed production of new targets for the coming run with the new masks.

Done with an expanded target production effort and QA:D. Steski (leader of effort), L. Sukhanova (contractor)

K. Gainey and S. Lynn (summer students)

W. Jackson and C. Zimmer (operators)

• Also some R&D using laser ablation to make such targets: still in the early stages

Target for Run9 and Run11

Run9 with used masks Run11 with new masks Laser production for run 11

(D. Steski)

Path Forward for pC CNI Polarimeter

New FEE (current sensitive preamplifiers): installed for Run 11

Same BNL made Si 2mm strip detectors. If ready install 1mm strip type (test first)

Half (blue1 and yellow1) inside, half (blue2 and yellow2) outside

Tools for accelerator physicists: improve the capability for ramp measurements

Slow monitoring of leakage current and bias voltage.

Test Hamamatsu strip detectors smaller area (radiation hard, uniform, better resolution, less sensitive to background)

Test BNL 1 mm strip detectors smaller area to minimize promptsHAMAMATSU 3x30 mm single detectors – Tested in the AGS. Could be

used for the Jet but too large for the p-C polarimeters.

Calibration with the Polarized H-Jet

• In Run 9, the Jet is ran with both beams on the target separated 3mm vert. • Little additional background is introduced in the process• Achieve better than 5% statistical measurement in an 8-hr fill at 250 GeV• It then takes a few fills to calibrate the p-Carbon polarimeters

Energies Measured So Far

Weak (if any) energy dependence pp elastic scattering in CNI region is ideal for polarimetry in wide beam energy range

24 and 100 GeV ran with silicon detectorsmounted to one side thus higher t reach

Issues for the Jet • We have experienced some systematic shifts from run to run (100 GeV)

• The molecular hydrogen background was measured off line, it would be wonderful to do this online to assess any changes with running conditions. (At the minimum periodic checking)A must if one is to aim for better than 5% accuracies (eRHIC !)

• Replaced the broken silicon detector 1 (15% gain)

• Most important, we will dedicate some running time to better understand background sample and systematics

•If time permits (or a break in the action) we will install a couple of Hamamatsu photodiode detectors where we will benefit from the better energy resolution and reach lower t values

Preparations for Run 11• Establish T0 monitoring procedure along with regular alpha calibration:

Prompts locus fit (if we believe that the shift is constant) current loop connected to the spare WFD input Use a pure beam induced pulse Scintillation telescope (min 2 small counters) looking at the

target at 45-90 deg to detect high energy charged particles

• Equalize amplification in all channels and cable lengths

• At the beginning of the run carefully and manually make thetraditional DL fit on the whole detector basis.

• Establish connection between these T0's and T0 monitor (once),No longer use T0 as a fit parameterReady for the start of the run by Jan 1st

Preparations for Run 11• Establish T0 monitoring procedure along with regular alpha calibration:

Prompts locus fit (if we believe that the shift is constant) current loop connected to the spare WFD input Use a pure beam induced pulse Scintillation telescope (min 2 small counters) looking at the

target at 45-90 deg to detect high energy charged particles

• Equalize amplification in all channels and cable lengths

• At the beginning of the run carefully and manually make thetraditional DL fit on the whole detector basis.

• Establish connection between these T0's and T0 monitor (once),No longer use T0 as a fit parameter

Where do we stand?• The full team is on board.

• We have in hand a full complement of detectors for AGS and RHIC

• Will install the AGS polarimeter next week (full access) Ready for Dec 10th.

• The DAQ (WFD crate and computer) inside the RHIC tunnel is complete

• Detectors have been installed in Blue 1

• Will install Blue 2 by Monday to be followed by target installation.

• Yellow 1 could be installed soon after, will await the production of the 1mm detectors from Instrumentation before installing Yellow 2 followed by targets installation.• Working on software and ramp development.Ready for the start run by Jan 1st

Yet Another Polarimeter!

• The 2 O’clock IP is the location of the AnDY Test (see Akio’s talk)

• Only vertical spin orientation will be available

• The ZDC system will be re-installed

• A shower max detector will also be included along with the segmentation to and scalar readout to measure asymmetries

• This provides yet another polarimeter when STAR and PHENIX run with longitudinal spin orientations.