7/30/99Douglas E. Fields for the E950 Collaboration 1 A CNI Polarimeter for RHIC Spin Results from...
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7/30/99 Douglas E. Fields for the E950 Collaboration
1
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
7/30/99 Douglas E. Fields for the E950 Collaboration
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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.
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Initial tests - IUCF CE75
7/30/99 Douglas E. Fields for the E950 Collaboration
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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.
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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.
7/30/99 Douglas E. Fields for the E950 Collaboration
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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 .
7/30/99 Douglas E. Fields for the E950 Collaboration
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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