# Presentation: 583952

## Heavy Quarks Measurements with a Forward Silicon Upgrade      

**Heavy Quarks ****Measurements with a Forward Silicon Upgrade****      **

**April 29, 2005**

**μ**

**Patrick L. McGaughey**

## Outline

- Why Measure Heavy Quarks?
- Make quantitative measure of QGP properties
- PHENIX Silicon Vertex Endcap Detector
- Detector Design (4.6M$ cost)
- Simulations of Performance
- Estimated Event Rates
- Impacts on Muon Arm Performance
- Summary

## Why Heavy Quarks ?

**Heavy quarks can provide a unique determination of the properties of the plasma**

-   **Have only qualitative evidence for QGP formation - can make  **
**   ****quantitative** **measurements with heavy quarks**
**  ****Heavy quarks (charm and beauty) - produced ****early**** in the **
**   ****collision.  ****Live long enough**** to sample the plasma**
-   **Intrinsic large mass scale** **allows precise calculations **
-   **Mass dependence of diffusion of heavy quarks determines **
**   ****plasma properties, e.g.**** viscosity and conductivity**
-   **Yields of charm and beauty pairs compared to first principle **
**   ****lattice simulations determine the ****energy density and **
**   ****temperature**
-   **Comparison between light and heavy quark suppression **
**   ****distinguishes between theoretical models of ****energy loss**** in the  **
**   ****QGP**

## Heavy Quarks - Signals

- Energy loss
- Energy loss of heavy quarks in QGP is expected to be much larger than in normal nuclear matter, contrast with light quarks

- Debeye screening
- J/ dissociates into DD in the QGP  measures temperature
- Flow
- Heavy quarks that thermalize in the QGP will show hydrodynamic flow
- Total charm
- In a QGP, increase from thermal production, strongly temperature dependent

- Currently large theoretical spread
- of "melting" temperatures of heavy
- quark bound states

## Evidence for the Quark-Gluon Plasma –  Hydrodynamic Flow

**Hydrodynamic pressure gradients**
**drive system evolution – results **
**in anisotropic particle emission**

- Au

- Au

- First time hydro limit with QGP equation-of- state is reached in heavy ion collisions!

- Anisotropy:

- No Flow

## D (charm)  e + X  Data from PHENIX Au+Au

**S/N < 1/1**

- 20+% Systematic error on yield

- v2 from electron measurement
- Note large errors, electrons (and muons) are difficult, but provide heavy quark signal

-  Charm and beauty inferred from
-  electrons, but electrons come
-  from many sources  Poor S/N!

**No flow**

**Large flow**

## Evidence for Strongly Interacting Opaque Plasma

**Au+Au**

**d+Au**

**Energetic quarks undergo **
**large energy loss**** in the QGP**

**Au******

******Au**

**R****AA**

**Strong suppression**** of pions from Au+Au versus p+p and d+Au collisions**

**Evidence for Strongly Interacting Opaque Plasma**

**Data – PHENIX (from cover of PRL!) **
**Predictions – Vitev, LANL JRO**

**Absence of QGP effect **

## Measuring Plasma Characteristics Using Quark Energy Loss

- non-equilibrium field theory transport coefficients into the evaluation of
- energy loss

**Measuring Plasma Characteristics Using Quark Energy Loss**

- Light quark energy loss

-  **State-of-the-art ****heavy **
**   ****quark E-loss calculations**

**Ivan Vitev**

## The PHENIX Detector

**The PHENIX Detector**

**Muon Arm**

**Muon Arm**

- Au

- Au

- J/

## Silicon Vertex Detector Upgrade

**Silicon Vertex Detector Upgrade**

- Au 

-  Au

**Endcaps detect following by **
**displaced vertex (********r, ********z) of muons:**
**    ****D (charm) ******** μ**** + X**** **
**    ****B (beauty)******** μ**** + X**
**    ****B ******** J/ ******** + X ******** μ****+ ****μ******

- Si planes constructed of strips 50 m by few mm long

- Pinpoint the decay vertex
- to eliminate backgrounds!

## Design of SVD

** ****4 Tracking stations composed of Si pixels, 50 um by few mm long**
** ****Electronics recently developed by FNAL, ~250,000 channels / pixels. **
**  ****First low power, high speed and high resolution pixel detector**
** ****Can detect large numbers of**** B decays ****and ****D decays per year**** at RHIC**

**Design of SVD**

- x

- x

- x

- x

****

## Hytec, Inc. Conceptual Design of PHENIX Vertex Detector Upgrade

- April 1, 2005?

## Vertex Detector CAD Drawings

## Vertex Detector CAD Drawings

## Endcap Detector Components - Conceptual layout of the PHX pixel readout chip. 

- Left panel : Green is bonding, blue the programming interface, red the discriminator, orange the pipeline and yellow the digital interface. Right panel : bonding layout, 200 micron pad spacing. Signal and power bus is routed on the surface on the chip.

- PHX is derived
- from BTeV FPIX
- readout chip

- 512 channels/chip
- Bump or wire bonds

## Endcap Detector Components –Conceptual Detectors

- Three silicon detectors sizes - largest has 6 chips with 3072 strips, intermediate has 5 chips with 2560 strips, smallest silicon has 3 chips and 1536 strips.

- mm

## Endcap Detector Assemblies

- Octagon panel structure with cooling channel.  Heat load is 0.1 W/cm2. Detectors mount on front and back.

- Octagonal disk structures for the endcap ministrips.  Cooling tubes shown to demonstrate number and routing.

## Endcap Detector Electronics Chain

## Overview of Asynchronous              Panel Readout

- Simulations give 0.7% max
- Occupancy, 1st layer, in central Au-Au

## Overview of Receiver Board

- Physical interface – PCI cards in Linux farm

## Endcap Tracker Specifications

- Outer envelope : radius 20cm,  length 80cm
- Silicon : inner radius 2.5cm,  outer radius 14 cm
- Radiation length goal : 1% per disk

| Disk | Z cm | Height cm | Area cm2 | Chip
Count | Power 
Watts | Volts | Amps |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 20 | 6.6 | 678 | 480 | 22 | 1.8 | 12 |
| 2 | 26 | 10.6 | 1374 | 768 | 35 | 1.8 | 19 |
| 3 | 32 | 18 | 2255 | 1056 | 48 | 1.8 | 26 |
| 4 | 38 | 18 | 2255 | 1056 | 48 | 1.8 | 26 |
| Total |  |  | 6562 | 3360 | 151 |  | 84 |

## Dramatic Signal / Background Improvement 

**Dramatic Signal / Background Improvement **
**             ****for Heavy Quarks with SVD**

- _charm_

- beauty

- pT  (GeV/c)

**Simulated Signal to Noise for D********    +X without SVD and with SVD, 10 X improvement is signal / background  ******** accurate  ****yield, slope**** of charm**

- pT  (GeV/c)

- Muon Events

- _charm_

- _Background__ _

- _Background_

- Before vertex cuts

- After vertex cuts

## Endcap performance - Vertex Resolution for Single Muons

- B lifetime is ~ 1 mm at low pT()=1.7 GeV
- c (B+-) = 496 um, c (B0) = 464 um
- c(D+-) = 315 um, c(D0) = 124 um

- Charm: =290 m

- Beauty: =230 m

- Simulated endcap z-vertex resolution for
- D    +X     and
- B    +X

- Z reconstructed

## Simulation of B-> J/-> with Endcap VTX

- Decay Distance (cm)

- 1mm vertex cut eliminates
- >99.95% of prompt J/

- B decays

- Prompt
-    J/

- 1mm cut

- Ratio of B decay
- to prompt J/
- ~ 1%

- σ=133μm

- RHIC 10*L0
- ~400 B-> J/
- per day

- p+p
- √S=200 GeV
- L=1036

- Events

## Measurement of gluon shadowing and spin structure function with VTX

**Extracting gluon structure function**
- Vertex detector provides broad range in x in the predicted shadowing region (x <= 10-2) and at larger x
- Measure gluon shadowing in p+A versus p+p,
-     gluon spin in polarized p+p

- Gluon
- Shadowing
- Predictions

- coverage

## Correlation between Muon Momenta and Gluon x-Values for Charm Decays

- PZ  μ

- PT μ

- x1

- x2

- Similar correlation for Beauty decays

## PHENIX Decadal Plan

## PHENIX Run Plans from Beam Use Proposal

- _Done_

- _Now_

- 

## From Tony Frawley, for two full silicon endcaps.

## Other Benefits of VTX upgrade to PHENIX muon program

- , J**/**, ’** ****-** VTX will improve mass resolution and background
- 		    rejection.
- , ’, ’’ – VTX can improve detection of these at rapidities 		       near zero.
- μ+ μContinuum - S/N can be greatly improved by VTX. Charm,               		           beauty and Drell-Yan pairs can be separated.
- 		           Possible detection of thermal charm pairs.
- e μpairs– VTX upgrade would improve S/N of these charm decays.

## Summary

- Goal:
- Detailed study of Heavy Quark production in p-p, p-A (d-A) and  A-A collisions at RHIC.
- Physics with VTX upgrade
- Total charm and beauty cross sections, thermal charm
- Energy loss and flow of charm and beauty in nuclear/quark matter
- Nuclear dependence (gluon shadowing) of charm and beauty production over a wide x range
-  G(x) measurement over wide x range (polarized protons)
- Proposed Silicon vertex detector
- 2 Si end caps (4 mini-strip layers each)
- Proposal for central Si barrel sent to DOE (July 2004), proposal for endcap to follow in 2005.

## Backup slides

## From Tony Frawley, for two full silicon endcaps

## Cocktail Calculation

_**Cocktail Calculation**_

-  p**T** distribution of 0 are constrained
-   with PHENIX 0  and  measurement
-  p**T** slope of , ’  and  are
-   estimated with m**T** scaling
-   p**T** = sqrt(p**T****2 **+ Mhad**2**** – **M**2**)
-  Hadrons are relatively normalized by
-   0 at high p**T** from the other
-   measurement at SPS, FNAL, ISR, RHIC
-  Material in acceptance are studied for
-   photon conversion
- Signal above cocktail calculation can  be seen at high p**T**

**Notes:**
We calculated the cocktail of electron from the sources we considered.
In this calculation, pt spectra of pi0 are constrained with PHOENIX neutral 
and charged pion measurement. 
Spectral shape of the other hadrons are estimated by using mT scaling.
The yield of the other hadrons are relatively normalized by pi0 at
High pt. That normalization factor are taken from the other measurement
In proton induced collisions at those place.
Amount of material in our detector are studied to estimate the contribution 
From photon conversions.
Right figure shows the expected electron yield from several sources
and this black line is a total yield of all expected sources. 
You can see some difference between data and expected yield at
High pt.

## Direct Observation of Open Charm and Beauty

**will allow clean identification of **
**charm and bottom decays**

**Need secondary vertex resolution < 50 ********m (barrel), ****	****< 150 ********m (barrel) **

**Direct Observation of Open Charm and Beauty**

_**Detection options:**_
** ****Beauty and low p****T**** charm through   ****	****displaced e and/or ******
** ****Beauty via displaced J/******
** ****Charm through D ******** ******** K **

- Central arm
- & barrel VTX

- muon arm & endcap VTX

## Silicon Vertex Upgrade

**Endcaps detect following by **
**displaced vertex of muons :**
**D ******** μ** **+ X**
**B ******** μ** **+ X**
**B ******** J/ ****** **+ X** ****** μ****+ ****μ******

**IP**

**μ**

**B**

**Secondary vertex resolution ~133 ********m**

**Endcap mini-strips :**** **
**50 ********m x few mm long**
**~1.0% X****0 ****per layer**
**Instrumented with BTeV ASICs**