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