7/30/99 Douglas E. Fields for the E950 Collaboration

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A CNI Polarimeter for RHIC Spin Results from IUCF CE75 & AGS E950

M. Bai, G. Bunce*, H. Huang, Y. Makdisi, T. Roser, A. Rusek, M. SyphersM. Bai, G. Bunce*, H. Huang, Y. Makdisi, T. Roser, A. Rusek, M. SyphersBrookhaven National LaboratoryBrookhaven National Laboratory

K. Imai* , M. Nakamura, J. Tojo, K. Yamamoto, L. ZhuK. Imai* , M. Nakamura, J. Tojo, K. Yamamoto, L. ZhuKyoto University/ RIKENKyoto University/ RIKEN

B. Bassalleck, S. Eilerts, D.E. Fields , B. Lewis, B. Smith, T.L. ThomasB. Bassalleck, S. Eilerts, D.E. Fields , B. Lewis, B. Smith, T.L. ThomasUniversity of New MexicoUniversity of New Mexico

Y. Goto, M. Ishihara*, K. Kurita*, N. Saito*, A. TaketaniY. Goto, M. Ishihara*, K. Kurita*, N. Saito*, A. TaketaniRIKENRIKEN

D. UnderwoodD. UnderwoodArgonne National LaboratoryArgonne National Laboratory

J. Doskow, K. Kwiatkowski, B. Lozowski, H.O. Meyer, B. v. Przewoski, T. RinckelJ. Doskow, K. Kwiatkowski, B. Lozowski, H.O. Meyer, B. v. Przewoski, T. RinckelIndiana University Cyclotron FacilityIndiana University Cyclotron Facility

I. Alekseev, D. Svirida, V.KanavetsI. Alekseev, D. Svirida, V.KanavetsITEPITEP

A. Deshpande, V. Hughes A. Deshpande, V. Hughes Yale UniversityYale University

*RIKEN/BNL Research Center*RIKEN/BNL Research Center

7/30/99 Douglas E. Fields for the E950 Collaboration

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A CNI Polarimeter for RHIC Spin Results from IUCF CE75 & AGS E950

→Motivation for CNI Polarimeter

→CNI Theoretical Status

→Initial tests - IUCF CE75 and Kyoto tests

→AGS E950 Experimental Setup

→E950 Analysis

→E950 Results

→RHIC Polarimeter Preliminary Design

7/30/99 Douglas E. Fields for the E950 Collaboration

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Motivation RHIC schedule

First Year running Oct.’99 - Aug. ‘00 Siberian Snakes installed Spin Rotators not installed yet Commissioning only, No Spin Physics

Second Year running Oct. ‘00 - Aug. ‘01 Spin rotators installed Higher (Blue Book) Luminosity

Good Physics (G)

BUT: Need relative polarimeter for First Year commissioning !

7/30/99 Douglas E. Fields for the E950 Collaboration

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Motivationp + C CNI polarimeter

Pros Inexpensive setup Solid target High figure of merit Little energy

dependence Polarization profile

ConsX Difficult Carbon recoil

detectionX Not absolute

7/30/99 Douglas E. Fields for the E950 Collaboration

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Theoryp+C Coulomb Nuclear Interference

CNI is an interference effect between the purely Coulombic spin-flip term and the hadronic non spin-flip term in the scattering potential.

For the interference term to be important, the scattering must take place “outside of the nucleus (r>>R), but well within the screening radius of the atomic electrons (r<<ao)”.

7/30/99 Douglas E. Fields for the E950 Collaboration

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CNI analyzing power is given by:

so no direct energy dependence.

At 25 - 250 GeV, Hadronic AN is thought to be <10% of

the CNI AN .

Theory

ApAtotp

N y

y

m

ZA

211

82

23

2

Z8

ty

pAtot g

mt

gA

2

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Theory

A

900keV

pp

pC

E950

450keV

q

pk

q=p-k

t = -q2

12C

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Measurementspp elastic at 200GeV/c (E704)

Physical Review D48 (1993) 3026-3036.

Curve has no hadronic spin flip.

7/30/99 Douglas E. Fields for the E950 Collaboration

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Initial tests - IUCF CE75

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CE75 Silicon

• Two standard Silicon detectors around 90o.

• Off-the-shelf on-board pre-amps.

• Cooled FET’s and silicons.

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IUCF CE75 Results

•Red points are for detector closer to 90o.

•So, green points (more forward detector) have higher Carbon energy.

•Matches predicted angle vs. energy.

•~200KeV threshold.

7/30/99 Douglas E. Fields for the E950 Collaboration

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Silicon Detector Re-design• 12 Channel 6 channel.

• On-board pre-amps.

• Cooled by mount.

Silicon Detector

Pre-amp location

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Initial tests - Kyoto

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Kyoto Results

• Could resolve down to 200keV Carbon recoils.

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AGS E950 Experimental Setup

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AGS E950 Experimental Setup

e e

MCP MCP

Silicon strip detector

C

Micro ribbon Carbon target

0 13

Carbon foil

Energy measurement

TOF measurement

25 cm

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Targets

• Carbon Ribbons

• 6m wide

• 3.7g/cm2 thick

• 3cm long

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Micro-Channel-Plate Detectors

MirrorMCP

Si PC board

Mirror

Silicon

Repeller

AcceleratorC foil

e-

12C

MCP

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Data Acquisition

• Read out events at end of spill.

• Home made Linux based acquisition.

• On-line analysis capable.

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E950 On-line Analysis

Carbon

Target Out Target In

ADC distribution

TD

C d

istr

ibut

ion

•Target out configuration still had a frame.

•Rate was sensitive to beam position.

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E950 Analysis

Si only Si -MCP

nsns

Projection along the profile

•Bunch width was ~25ns.

•TDC start was beam RF.

•Inherent 7.2ns width from beam bunches.

•Using Si - MCP gives inherent Si time resolution of 2.5ns .

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E950 Analysis

TD

C V

alue

s (n

s)

4 sigma cut

6 time bins prompt

Carbon band

ADC values(ch)

•Since E calibration not good (yet), use time slices to get -t bins.

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E950 Results

Time bins

Asy

mm

etry

Error bars are statistical only

•Follows general trend expected.

•Not yet absolute (at any scale).

-t

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RHIC Polarimeter Preliminary Design

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RHIC Polarimeter Preliminary Design