Understanding the Origin of the Nucleon Spin Andi Klein, Melynda Brooks, Pat McGaughey and Matt...

Understanding the Origin of the Nucleon SpinAndi Klein, Melynda Brooks, Pat McGaughey and Matt Stettler

Research Goals:

• Use Deeply Virtual Compton Scattering (DVCS) and Generalized Parton Distributions to extract the angular momentum of the quarks. • Design the necessary hardware and software to measure the quark angular momentum at Jefferson Lab, using the CLAS12 spectrometer.

Feynman diagram for the virtual Compton contribution to the eNeN reaction.

R&D Approach• Simulate e+D and e+3He events, and determine the detection efficiency of the recoil proton.

• For the development of the necessary trigger tracking algorithms, we will simulate the physics and the detector response with Monte Carlo simulations.

• Transfer the software into the FPGAs and perform timing and resolution tests for the different algorithms.

• A new amplifier / discriminator board (ADB) for the CLAS12 drift chambers will be designed and constructed using FPGAs that perform as TDCs and implement triggering algorithms

• Based on the simulations from Task1, we will develop and submit an experimental proposal to JLAB for 12 GeV nDVCS running.

Timeline and budget

Andi Klein (30%) and Melynda Brooks (20%) will work on simulations and the tracking code development . Matt Stettler (20%) and Pat McGaughey (20%) will work on the ADB design and prototype.

In the second year, AK and MB will work 20% on the FPGA code, while PLM and MS will finalize the prototype design.

Will hire a PostDoc at 50 % for the third year, in order to perform some of the testing. At this point, AK, MB and PLM will each work 20% on the project.

M&S budget of 30K for the first year, 20 K$ in the second and 10K$ in the third year.

• Large Acceptance detector• JLAB 12 GeV Upgrade: NSAC Highest Priority• Current Trigger Design: 200kHz average L1 Trigger

Rate, Dead-timeless, Pipelined, 2ns bunch crossing (CW Beam) reduce to 20 kHz for DAQ

• Problems:• In e-trigger about large fraction not electrons; in

DVCS ~90%, large costs for storage• Some new physics not possible, which interest

has only started after approval of CD3, letters of intent

• Old FASTBUS based system, no upgrade possible

CLAS12

SiliconTracker

Central TOF

Wire Chambers

HighThresholdCerenkovCounter

CerenkovCounter

Pre-Cal E-CAL

Clas 12 GeV

1 sector

2SL/chamber

672 Wires/SL