# Presentation: 474214

## Gluon Polarization Measurements with Polarized Protons at RHIC

**Gluon Polarization Measurements with Polarized Protons at RHIC**

**John Koster**
**University of Illinois, Urbana Champaign****Preliminary Exam****November 28, 2007**

## Physics Motivation:	On the Origin of the Proton Spin

**Interpretation of Past Measurements****	****Polarized Deep Inelastic Lepton Proton Scattering**
**Discussion of Measurements in Progress****	****Inclusive measurements with Polarized Protons collisions**
**New Probes****	****Di-Hadron measurements with Polarized Protons collisions**
**Instrumentation Necessary for Proposed Measurement****	****Implementation of a new forward calorimeter**

- Preliminary Exam 11/28/07

## Physics Motivation

**Physics Motivation**

**Constituents:                    quarks = u, d, s  **
**and gluons**

**Quark Spin**** +**

**Gluon Spin**** +**

**Orbital Angular Momentum**

**Proton Spin**

**1fm**

- Preliminary Exam 11/28/07

## Physics Motivation

- Preliminary Exam 11/28/07

## Physics Motivation:	On the Origin of the Proton Spin

**Interpretation of Past Measurements****	****Polarized Deep Inelastic Lepton Proton Scattering**
**Discussion of Measurements in Progress****	****Inclusive measurements with Polarized Protons collisions**
**New Probes****	****Di-Hadron measurements with Polarized Protons collisions**
**Instrumentation Necessary for Proposed Measurement****	****Implementation of a new forward calorimeter**

- Preliminary Exam 11/28/07

## Status of Polarized Distribution Functions

** ****Up Quark polarized parallel to direction of proton spin**
**Highly polarized at mid-to high- x.**
** ****∆****u ~ 0.85**

- From: AAC, Phys.Rev.D74:014015,2006.

- Preliminary Exam 11/28/07

## Status of Polarized Distribution Functions

** ****Down Quark polarized anti parallel to direction of proton spin**
**Highly polarized at mid-to high- x.**
-  **∆****d ~ -0.35**

- From: AAC, Phys.Rev.D74:014015,2006.

- Preliminary Exam 11/28/07

## Status of Polarized Distribution Functions

**Assumption: ****Δ****u(x) = ****Δ****d(x) = ****Δ****s(x) at Q****2****=1GeV****2**
** ****AAC fit determines ****Δ****q(x) **
**Large uncertainties **
** ****Δ****q = -0.05 +/- 0.01****Evaluated at Q****2 ****= 1 GeV****2**

- From: AAC, Phys.Rev.D74:014015,2006.

- Preliminary Exam 11/28/07

## Status of Polarized Distribution Functions

** ****Gluons distribution has large uncertainties**
** ****Sign of distribution unknown**
** ****Δ****G = 0.31 +/- 0.32****Evaluated at Q****2**** = 1 GeV****2**

- From: AAC, Phys.Rev.D74:014015,2006.

- Preliminary Exam 11/28/07

## Physics Motivation:	On the Origin of the Proton Spin

**Interpretation of Past Measurements****	****Polarized Deep Inelastic Lepton Proton Scattering**
**Discussion of Measurements in Progress****	****Inclusive measurements with Polarized Protons collisions**
**New Probes****	****Di-Hadron measurements with Polarized Protons collisions**
**Instrumentation Necessary for Proposed Measurement****	****Implementation of a new forward calorimeter**

- Preliminary Exam 11/28/07

## Accessing the Polarized Gluon Distribution

**Polarized DIS**
**	****+ Clean measurement of x**
**	****-  Extraction of gluon requires large range of log (Q****2****)****	****   Measurements of ****Δ****G may be possible with a future high ****	****   energy polarized electron-proton collider**
**Polarized Protons**
**	****+ Gluons probed directly**
**	****-  Measurements not directly sensitive to x**

- Preliminary Exam 11/28/07

## The Relativistic Heavy Ion Collider

**Brookhaven National Laboratory, Long Island**

- Preliminary Exam 11/28/07

## Polarized Protons in RHIC

**Polarized Protons in RHIC**

**AGS**

**LINAC**

**BOOSTER**

-   Polarized Source 1 mA, H-  70-80% polarization

- Spin Rotators

- Partial Snake

- Siberian Snakes

-   200 MeV Polarimeter

-   Rf Dipole

-  RHIC pC Polarimeters

-  Absolute Polarimeter (H jet)

**P****HENIX**

**P****HOBOS**

**B****RAHMS & PP2PP**

**S****TAR**

- Siberian Snakes

- AGS pC Polarimeter

**Helical Partial**
**  ****Snake**

- Strong Snake

**Spin Evolution through Siberian Snake from:****http://www.agsrhichome.bnl.gov/RHIC/Spin/spinfigs/qcdspin-mackay.pdf**

**Spin Orbit through a Siberian Snake**

**110 Bunches****10****11 ****protons/bunch****106 ns bunch spacing****25 < Beam Momentum < 250 GeV**

**Siberian Snake**

- Preliminary Exam 11/28/07

## PHENIX Polarized Proton Data Samples

| Year Start/End | √s [GeV] | [pb-1] | Proton Polarization | Data Size [TB] | Nevents [109] |
| --- | --- | --- | --- | --- | --- |
| 2001/2002 | 200 | 0.15 | 15% | 20 | 3.7 |
| 2002/2003 | 200 | 0.35 | 35% | 35 | 6.6 |
| 2004/2004 | 200 | 0.35 | 46% | 35 | 6.6 |
| 2004/2005 | 200 | 3.8 | 47% | 262 | 85 |
| 2006/2006 | 20062.4 | 10.70.1 | 60~65% | 31025 | 23028 |
| 2007/2008* | 200 | 30 | 65% | ~870 | ~645 |

*** Projections**

**Source: **_[http://www.bnl.gov/npp/docs/pac0307/phenix_bup.pdf](http://www.bnl.gov/npp/docs/pac0307/phenix_bup.pdf)__[http://www.bnl.gov/rhic_ags/users_meeting/Workshops/1/MBai.pdf](http://www.bnl.gov/rhic_ags/users_meeting/Workshops/1/MBai.pdf)_**and PHENIX internal discussions for 2007/2008 projections**

**MPC Active.  Thesis data set**

**JK Contributions to Data-Taking Effort:**
**4+ months as MPC on-call expert**
**2 months on shift as Shift Leader, DAQ Operator, Data Monitor or HV/LV Controller**

- Preliminary Exam 11/28/07

## The PHENIX Detector

**Major Features:**
** ****Four Independent Spectrometer Arms**
** ****Flexibile event selection**
** ****High DAQ bandwidth (600 MB/s) to Disk**
** ****Good capabilities for particle identification**
** ****Limited Acceptance**

- Beam

- Preliminary Exam 11/28/07

## PHENIX Calorimetry

**-3              -2             -1                 0                1               2               3    pseudo-rapidity**

****** ****coverage          2******

**EMCAL**

**EMCAL**

**Detector Upgrade in Progress  **Available 2012

**MPC Timeline:**Summer 2005 -- IdeaJanuary 2006 -- South MPC InstallationOctober 2006 -- North MPC InstallationOctober 2007 -- Upgraded Light Distribution System InstallationBoth detectors available for run 08 pp+dA

- Preliminary Exam 11/28/07

## Kinematics for Inclusive ALL with PHENIX CA

**Proton #1**

**Proton #2**

**Central Arm**

**Inclusive ************measurements in PHENIX Central Arms**
**Probe a range in x****1****, x****2**
**Hadron p****T ****cuts change subprocess: qg, gg, qq**

**From S. Bazilevsky**

**From W. Vogelsang**

- 

- Log10(x)

- Counts

- Preliminary Exam 11/28/07

## ALL π0 with the PHENIX Central Arms

**Model Dependent Statement on the Gluon spin contribution is possible with A****LL**** measurements done at RHIC.**

**GRSV: M. Gluck, E. Reya, M. Stratmann, and W. Vogelsang **
**One set of parameterizations for the helicity distributions based on a QCD analysis of DIS data.**
**Std. gives the best agreement with DIS data**

**Calc. by W.Vogelsang and M.Stratmann**

- Preliminary Exam 11/28/07

## Comparison to Other Helicity Distributions Parameterizations

**Comparison to Other Helicity Distributions Parameterizations**

- Example: GS-C with node at x=0.1
- has ∫0.020.3ΔG(x)≈0 but ∫01ΔG(x)=1
- Similar for any parameterization which rises at sufficiently small x

- Gehrmann-Stirling Parametrizations

- Preliminary Exam 11/28/07

## Evaluation of Extrapolation Uncertainties to Small and Large x

- ∆G=∫01∆G(x) dx
- =∫00.02∆G(x) dx+∫0.020.3∆G(x) dx+∫0.31∆G(x) dx

- How big or small can the  unmeasured  contributions be?Use G(x) as bound for ∆G(x) in unmeasured regions

- Preliminary Exam 11/28/07

## CTEQ 6M Integrations

**Unpolarized parton distributions, CTEQ 6M**

**Estimates of ****∆****G with assumption of maximally polarized gluon ****(****∆****G(x)=G(x))**

**Functional form of ∆G(x) at large x is interesting, but maximum spin contribution is small****Constraints possible with mid rapidity measurements****Large Potential Spin Contributions**

|  |  | Q2=4 GeV2 | Q2=102 GeV2 | Q2=104 GeV2 |
| --- | --- | --- | --- | --- |
| XStart | XEnd | ∫G(x)dx | ∫G(x)dx | ∫G(x)dx |
| 10-4 | 0.02 | 53.0 | 169 | 279 |
| 0.02 | 0.30 | 4.96 | 4.47 | 3.65 |
| 0.30 | 1 | 8.55x10-2 | 2.71x10-2 | 1.1x10-2 |

- Preliminary Exam 11/28/07

## Physics Motivation:	On the Origin of the Proton Spin

**Interpretation of Past Measurements****	****Polarized Deep Inelastic Lepton Proton Scattering**
**Discussion of Measurements in Progress****	****Inclusive measurements with Polarized Protons collisions**
**New Probes****	****Di-Hadron measurements with Polarized Protons collisions**
**Instrumentation Necessary for Proposed Measurement****	****Implementation of a new forward calorimeter**

- Preliminary Exam 11/28/07

## Selection of Kinematics at RHIC using DiJets/Hadrons

**RHIC collides protons with ****√s**** = 200 GeV**
**Collisions with large transverse momentum similar to parton-parton elastic scattering**
- Reconstruct x1, x2 using kinematics of 2-body elastic collisions
**Use of hadrons as jet proxies smears relation**
**Choice of hadron and rapidity affects observed distribution of probed x****1,2**

**y****1,2** - rapidities of jets 1 and 2
**p****T**** ** - transverse momentum of jet

**1**

**2**

**4**

**3**

- Preliminary Exam 11/28/07

## Di-Hadron Event Simulations with Pythia

**Pythia: Monte-Carlo simulation package for simulating high energy collisions**
**Unpolarized processes only**
**Results should not be blindly trusted**
**Highly tuneable**
**Gives detailed event information**
**Detector Response Not Included****Useful for feasibility studies**

- 10100100110010011101010011101010010110

- 10100100110010011101010011101010010110

-  101 001001100100111010100111010101

-  101 10101111100101011110011011101

- 110110101011011

- Preliminary Exam 11/28/07

## Use DiHadrons to Tag x

**Use DiHadrons to Tag x**

**North Nose Cone Calorimeter****Broader x-range**

**Central Arm****AntiSymmetric, high-x/low-x events**

**South Nose Cone Calorimeter****Broader x-range**

**South MPC****Selects symmetry, high-x events**

- Log10(x2)

- η4

**Proton 1**

**Proton 2**

**4, ********0**

**3, ************–**** Trigger Particle**

**JK Contributions:****Study of accessing low-x through di-hadron channel in PHENIX presented at DNP07**

- Preliminary Exam 11/28/07

## Low-x: x-distributions and subprocess fractions

**Low-x: x-distributions and subprocess fractions**

- pT

- Subprocess Fraction

- X1,2

- Central Particle Required

- Forward and Central Particle Required

- 3.1 < η< 3.65η1 <  pT < 2 GeV/c

- -0.35 < η < 0.35

- quark-gluon scatteringgluon-gluon scatteringquark-quark scattering

- x1
- x2

- pT

- pT

- pT

- Subprocess Fraction

- X1,2

- Preliminary Exam 11/28/07

## Physics Motivation:	On the Origin of the Proton Spin

**Interpretation of Past Measurements****	****Polarized Deep Inelastic Lepton Proton Scattering**
**Discussion of Measurements in Progress****	****Inclusive measurements with Polarized Protons collisions**
**New Probes****	****Di-Hadron measurements with Polarized Protons collisions**
**Instrumentation Necessary for Proposed Measurement****	****Implementation of a new forward calorimeter**

- Preliminary Exam 11/28/07

## Contributions to the Realization of the MPC

**Calorimeter ****Design/Construction**

**Electronics****Design/Production**

**Revised Monitoring ****System**

**Installation**

**Built by a collaboration of 8 institutions led by UIUC.**

- Preliminary Exam 11/28/07

## MPC Construction at UIUC Nuclear Physics Lab

**MPC assembly team in Urbana**
- Frank Ellinghaus	Colorado
- Oleg Eyser		UCR
- Don Isenhower		ACU
- Andrey Kazantsev	Kurchatov
- Nathan Means		Stony Brook
- Ken Sedwick		UCR
- Cole Watts		ACU
- John Wood		ACU
- Ryan Wright		ACU
- -------------------------------------------------
- John Blackburn		UIUC
- John Koster		UIUC
- David Layton		UIUC
- Eric Thorsland	**	**UIUC
- Aaron Veicht		UIUC

**MPC Construction at UIUC Nuclear Physics Lab**

- Preliminary Exam 11/28/07

## Preparation of a Crystal

- PbWO4 Crystals from Kurchatov Institute

- Alcohol cleaning

- Tyvek wrap

- After a 36 hour cure the crystals are wrapped in aluminum foil and tetlar.
- Not so hard...

**Repeat 450 times!**

- Glued to an APD

**Preparation of a Crystal**

- Preliminary Exam 11/28/07

## Energy Calibration at Fermilab

**Meson Test Beam Facility**

**Fermilab**

**Test module at beam test**

- e- Energies:4, 8, 16, 33 GeV

**JK Contributions: Preparation of crystals, setup for beamtest, data taking shifts**

- Preliminary Exam 11/28/07

## MPC Installation

**PHENIX Technicians installing the SMPC**

**NMPC FEM**

**Fully Prepared Modules**

**Installed NMPC**

**Beampipe**

- Preliminary Exam 11/28/07

## Calibration using Minimum Ionizing Particle

- Counts

- Preliminary Exam 11/28/07

## Calibration using  Invariant Mass Peak

**Two photon invariant mass spectrum**Photon Pair Cuts
- Pair Energy > 8 GeV
- Asymmetry |E1-E2|/|E1+E2| < 0.6
- Noisy Towers (up to 25% of MPC) Excluded
- Width ~ 20 MeVFrom: Mickey Chiu

- Background
- subtracted

- All Pairs
- Mixed Events

- Counts

- Counts

- Preliminary Exam 11/28/07

## Transverse Single Spin Asymmetry: AN at √s = 62.4 GeV

- First MPC Result!

- Preliminary Exam 11/28/07

## Summary

**Large gluon spin contributions are possible at low x**
**	****Proposed A****LL ****measurement will access this region**
**Forward Calorimeter designed, built, installed and operated.**
**	****Large data sets already available with even larger samples soon to come**

- Preliminary Exam 11/28/07

## Extras

- Preliminary Exam 11/28/07

## High-X: x-distributions and subprocess fractions

- Pi0 Energy Cut [GeV]

- Pi0 Energy Cut [GeV]

- SubProcess Fraction

- <x1,2>

- Di-MPC

- Single MPC

- quark-gluon scatteringgluon-gluon scatteringquark-quark scattering

- x1
- x2

- <x1,2>

- Preliminary Exam 11/28/07

## Slide 39

- Preliminary Exam 11/28/07

- Simulations from Marco Stratman on di hadron production at forward and mid rapidity

- Preliminary Exam 11/28/07

## High-X DiMPC

- Projected Statistical Error Bars for Run 08Di-MPCValues for E>30 GeV not generated because insufficient Pythia Statistics

- Preliminary Exam 11/28/07

## Low-X: x-distributions and subprocess fractions

- Preliminary Exam 11/28/07

## Physics Output

**Physics Output**

**Contribution to Reaction Plane Measurement in AA Collisions**

- blue  : rxn_S - rxn_Nred   : mpc_S - mpc_Nblack : bbc_S - bbc_Npink  : rxn - mpcgreen : rxn - bbc** **

- The solid symbols are average cos values, whileThe open symbols are average sin.** **

- Preliminary Exam 11/28/07

## Beam Test Details

- MTBF - Secondary Beam from 120 GeV protons of Main Injector into Al target
- Momentum from 3 GeV to 120 GeV possible
- 4 second spills every two minutes, 4 cm spot size (momentum dependent)

*Proton beam*

- Al target

- Preliminary Exam 11/28/07

## PbWO4 Scintillating Crystals

- Dimensions: 2.2 x 2.2 x 18 cm3
- Radiation length: 0.89 cm
- Moliere radius: 2.0 cm : Smallest known scintillator moliere radius
- Hadronic Interaction Length: 22.4 cm
- Main emission lines: λ = 420-440 nm, 500 nm.
- Scintillating crystals on loan from the Kurchatov Institute, Russia.
- Developed for ALICE in collaboration with the North Crystal Company in Apatity, Russia.

- Preliminary Exam 11/28/07

**Notes:**
Talk about all numbers

## Avalanche Photodiodes and Preamp

*APD’s*
- Developed for the CMS experiment
- Manufactured by the Hamamatsu Corporation
- Peak response around main emission lines of crystal (420-440, 500 nm)

*Preamps*
- Preamps contributed by Hiroshima University, Japan.
- Developed for the ALICE and modified by Hiroshima U.

- Preliminary Exam 11/28/07

## Preparing the Area

**Before the lid comes off the box you should have:**
- Alcohol to clean the crystals
- Kim wipes
- Q-tips
**Well padded work areas** – the crystals can be damaged by contact with metal or sudden impacts.  UIUC used the foam from the boxes + felt + several layers of Kimwipes.
- A diamond tipped scribe
- Gluing stands

- Preliminary Exam 11/28/07

## Unpacking the Crystals: Person #1

- Pry off the lid.
- You should find a packing list
- The crystals are wrapped in cotton and paper (paper on the inside)
- As you unpack the crystals cross their ID off the packing list

- crystal

- A box with the lid off

**Unpacking the Crystals: Person #1**

- Preliminary Exam 11/28/07

## Scribing + Rough Cleaning: Person #1

- Scratch off the crystal ID.
- Do a rough cleaning with an alcohol soaked Kim-wipe.  Get rid of sticker residue and the arrow
- Write the crystal ID on a thin strip of paper and put the crystal on top of it.

- Crystal ID

- Arrow – done with a marker

- Crystal ID would go here

**Scribing + Rough Cleaning: Person #1**

**An unwrapped crystal**

- Preliminary Exam 11/28/07

## Fine Cleaning + Tyvek Wrap

**A tyvek wrapped crystal**

- Person #2 wears cotton gloves almost the entire time
- Do a fine cleaning of the crystal.  I recommend using two passes on each crystal face with a clean, alcohol-soaked kim wipe.
- Wrap the crystal in the pre-cut tyvek:  Take off one glove.  Use it to tape the tyvek at the flap, and at the side.  Your gloved hand should be holding the crystal
**Warning: The crystal can and will slip out the un-taped end.  Be very careful**

- tape

**Photo diode end**

**APD end**

**Fine Cleaning + Tyvek Wrap**

- Preliminary Exam 11/28/07

## Preparing the APD + Holder

- UV gun

- Glue Syringe

- APD holder

- preamp on holder

- Scribe the APD ID onto the APD holder.  Outline it with a thin marker.
- Put a line of glue down on the apd/apd holder.  The 2 lines of glue are shown  as a dashed yellow line
- Glasses on.  Make sure no one is around you.  The UV light damages unprotected eyes
- Hit the foot-switch.  The UV source should be pre-configured to give you a 20 second burst.

**Preparing the APD + Holder**

- Preliminary Exam 11/28/07

## Gluing p1: Person#3, or Person#4 if there is one

- Clean off the APD face with alcohol and a Q-tip
- Wait for it to dry, or dry it off with a Q-tip
- Put glue on APD (requires skill to do properly.  Big challenge is to keep air bubbles out)
- Place APD on the gluing stand.  Slide crystal onto the APD.
- Write gluing time on the slip of paper with the crystal ID on it.
- When gluing is complete put kim wipes over the crystal

- Wrapped Crystals on gluing jig

**APD ID.  Crystal ID is on the other side**

**Crystal ID w/ gluing time**

**Gluing p1: Person#3, or Person#4 if there is one**

- Preliminary Exam 11/28/07

## Gluing p2: Person#3, or Person#4 if there is one

**Used 3145 RTV MIL-A-46146 adhesive/sealant-clear**
**	****This glue comes in a long cylinder and is removed using commonly found glue extruders.**
**We transferred the glue from the extruder into a syringe (this gives us finer control when applying the RTV).**
**We had enough gluing jigs to do 60 crystals in a day.  This was usually a long day.**
**Crystals should be inspected for air bubbles after gluing.  The crystals are easy to clean after only 1 hour of curing.**
**Bubbles did develop after 12 hours of curing.  These were more difficult to clean than after just 1 hour.  At best the cleaning will take 15 minutes (the glue on the APD sticks very well.  One APD took an hour to clean) and at worst the pins connecting the APD to the pre-amp board will break.  We did not attempt to repair any of these APD’s (~3 broke)**
**My advice: inspect early.**

**Gluing p2: Person#3, or Person#4 if there is one**

- Preliminary Exam 11/28/07

## Dried Crystals

**The gluing jigs needed to be cleared, so we took them off the jigs and into holding areas.**
**The white strip underneath the crystals was a layer of foam.  We put it there to minimize the force on the glue joint.  It also makes picking them up easier.**

**Dried Crystals**

- Preliminary Exam 11/28/07

## Overview of the drawings
I will break down the beam pipe going from MuID-S to MuID-N piece by piece.
Important Information
Overview of the planned changes to the PHENIX beampipe.

- I will break down the beam pipe going from MuID-S to MuID-N piece by piece.
- Important Information
- Overview of the planned changes to the PHENIX beampipe.

**PHENIX & The Beam Pipe**

- Preliminary Exam 11/28/07

## PHENIX w/ Focus on BeamPipe

- This is from an Autocad drawing done by Richie and Don: 026.pdf
- Part F no longer exists.  This was a stand used before the South Magnet was installed.

**PHENIX w/ Focus on BeamPipe**

- Preliminary Exam 11/28/07

## South Piston Hole Beampipe

- This is from an Autocad drawing done by Richie and Don.
- A pdf copy is available: 047.pdf
- Zoom-in’s and explanations will follow.

**South Piston Hole Beampipe**

- Preliminary Exam 11/28/07

## North Piston Hole Beampipe

- This is from an Autocad drawing done by Richie and Don.
- A pdf copy is available: 038.pdf
- Zoom-in’s and explanations will follow.

**And there’s a bellows, but it doesn’t have a “Bellows Spreader” on it.  The South’s “bellows spreader” increases the South’s keep out zone.**

**North Piston Hole Beampipe**

- Preliminary Exam 11/28/07

## South Mu ID 

- South Mu ID

- Valve – isolates PHENIX from the rest of the ring.  Close the valve, and we can break vacuum without affecting the ring.

- Bellows – I & 2

- BPM – beam position monitor

- Vacuum Pump

## Fixed support – no longer exists.  Taken out with installation of South Magnet

- Sliding Beam Pipe SupportShown in Section C of 026.pdf

- Flange and BellowsShown in Detail D of 026.pdf & in 047.pdf

- Conversion from 5” ID to 3” ID steel beam pipe

- South Muon Magnet

- Preliminary Exam 11/28/07

## Beam pipe conversion from steel to beryllium.  This is a rigid joint.  I believe the transition from beryllium to steel is inside the central magnet steel

- Central Region

- Preliminary Exam 11/28/07

## V – Shaped support : The steel beam pipe is not rigidly held here.  Nor can it roll.  It can scrape through the V.

- Flange and Bellows

- Conversion from 3” ID to 5” ID steel beam pipe

- North Muon Magnet

- Sliding Beam Pipe SupportShown in Section C of 026.pdf

- Preliminary Exam 11/28/07

## North MuID

- Very similar to the South case.  Valve, flanges, vacuum pump...

- Preliminary Exam 11/28/07

## Important Information

- There must be a bellows between any two fixed points to give the beam pipe room to expand/contract in the z-direction.

- Fixed Point

- Rolling Support

- Bellows

- From 026.pdf it looks like this is a non-sliding support, positioned just before the transition to beryllium.  This seems to break the rule.  I will follow up with Don tomorrow.

- Sliding Support

- Preliminary Exam 11/28/07

## Three Beam Pipes

**Beryllium section is rigidly connect to steel piece.**

- Preliminary Exam 11/28/07

## Planned Changes

- Both the beampipe thickness and inner diameter will be decreased.  Time frame unknown, but it is connected with the Nose Cone Calorimeter upgrade.
- The plan is to have beryllium up to the nose cone, have a bellows there and make the transition to steel.  It’s difficult to tell, but it looks like the current beampipe makes the steel-beryllium transition inside the central magnet
- We could make the argument that we are moving the south bellows from the magnet hole to the south nose cone.

- Preliminary Exam 11/28/07

## What would this give us?

**Bellows Spreader Diameter – 6.50”**
**Flange Diameter – 4.62”**
**We’d reduce the keep out zone radius by almost an inch so... we’d be at the keep out zone of the North MPC...  4 5/8”**
**The south drawings are in pdf’s 043, 044, 045, 046 & 047.**

- Preliminary Exam 11/28/07

## Numbers Explained (i)

**6.5”**

**6.5” is diameter of spreaders**
**5.5” is the diameter of the circle formed by the bellow spreader rods**

- Preliminary Exam 11/28/07

## Numbers Explained (ii)

**4.62” is the flange diameter. – This would make out keep out diameter the same as the NMPC.**

- Preliminary Exam 11/28/07

## Block Diagram of Data Flow

**Block Diagram of Data Flow**

- Preliminary Exam 11/28/07

## Crystal to Preamp Signal

- APD

- Pre Amp

- Signal Output

- Photon

**Crystal to Preamp Signal**

- Preliminary Exam 11/28/07

## Driver Board

- The Driver board has four purposes.
- 	1) Because of the slow fall time coming out of the pre-amp (~300μs) the circuitry is differential to shorten the pulse time
- 	2) Get the power to the APD/Pre Amp
- 	3) Amplify the signal up to a max of +4V
- 	4) Send out negative and positive copies of the signal

**Driver Board**

- Preliminary Exam 11/28/07

## Twisted Pair Signal Cable

- The purpose of the twisted pair cable is to send simultaneous positive and negative copies of the signal from the Driver board to the Receiver board.
- What this does is that the noise in both the positive and negative should be the same and so when you combine the two signals, the noise cancels from the two.

**Twisted Pair Signal Cable**

- Preliminary Exam 11/28/07

## Receiver Board

- The Receiver board gets a positive and negative copy of the signal from the Driver board. It subtracts the negative signal from the positive signal to get the original signal with noise subtracted out.  This then gets the gain cut by 1⁄4 and flipped because the FEM expects a negative pulse of no more than 1V.

**Receiver Board**

- Preliminary Exam 11/28/07

## Front End Module/Electronics

- The electronics that gets the signal out to the DAQ

- The parts of the FEM are
- 	1) Trigger Sum Card
- 	2) 6 ASIC Cards
- 	3) Heap Manager Card
- 	4) Data Format Card
- 	5) ARCNET Card

- For another intro into the FEM, go to http://www.phenix.bnl.gov/WWW/emcal/computing/online/EmcDoc112602/

**Front End Module/Electronics**

- Preliminary Exam 11/28/07

## ASIC Card

**ASIC Card**

- Preliminary Exam 11/28/07

## Geometric Mapping of FEM channels

- _Geometric Mapping of FEM channels_

- Grey is FEM 0
- Packet id 21003

- Colors and white are FEM 1
- Packet id 21004

- Inside the black box are channels only in the north and not in the south

- 147

- 161

- 256

- 244

- _Numbers with arrows are in south but not north_

- Preliminary Exam 11/28/07

## Communicating with PHENIX

- FEM sends it’s data to a Data Collection Module (DCM), and gets trigger signals from the Granule Timing Module (GTM)
- DCM - The DCM receives data from the FEM through an optical cable.  The DCM talks to the PHENIX DAQ.  When a trigger is sent out to the FEM it needs to know how long ago the actual data happened.  This delay is set in the GTM file.
- GTM - The GTM tells the FEM when to send its data to the DCM.  Communication is done via a 2nd optical fiber.  It ensures that the data is matched with other PHENIX subsystems on an event by event basis.

- Preliminary Exam 11/28/07

## From Mei Bai’s Slides at the RHIC/AGS User’s Meeting:

**From Mei Bai’s Slides at the RHIC/AGS User’s Meeting:**
**http://www.bnl.gov/rhic_ags/users_meeting/Workshops/1/MBai.pdf**

- Preliminary Exam 11/28/07

## From Mei Bai’s Slides at the RHIC/AGS User’s Meeting:

**From Mei Bai’s Slides at the RHIC/AGS User’s Meeting:**
**http://www.bnl.gov/rhic_ags/users_meeting/Workshops/1/MBai.pdf**

- Preliminary Exam 11/28/07

## RHIC Run Information

- Preliminary Exam 11/28/07

**From: http://www.agsrhichome.bnl.gov/RHIC/Spin/spinfigs/qcdspin-mackay.pdf**

- Preliminary Exam 11/28/07

**From: http://www.agsrhichome.bnl.gov/RHIC/Spin/spinfigs/qcdspin-mackay.pdf**

- Preliminary Exam 11/28/07

## Analyzing Power

- Preliminary Exam 11/28/07