# Presentation: 738873

## GRETAThe Gamma-Ray Energy Tracking Array

- I-Yang Lee
- Lawrence Berkeley National Laboratory

## Outline

**Physics opportunities**** **
- GRETA white paper
- Examples in plenary talks of
- Augusto Macchiavelli
- Thomas Glasmacher
**Technical accomplishments**
**Cost and schedule**
**Management structure**
**Auxiliary detectors**
- Demetrios Sarantites

**GRETA White paper**

## Principle and advantages of -ray tracking

**Efficiency – **Proper summing of scattered gamma rays, no solid angle lost to suppressors
**Peak-to-background – **Reject Compton events
**Doppler correction - **Position of 1st interaction
**Polarization – **Angular distribution of the 1st scattering
**Counting rate - **Many segments

- 3D position
- sensitive
- Ge detector

- Resolve position and energy of interaction points

- Determine
- scattering
- sequence

## Technical Challenges and achievements

**Advances in Ge detector production**
** ****Segmentation size ~ 2 cm → 30-40 segment/crystal**
** ****Closely pack irregular tapered hexagon shape**
** ****Fast electronics **
** ****ADC with 10 nsec sampling rate, > 12 bit resolution**
** ****Efficient algorithms**
** ****Signal analysis – position resolution 2 mm**
** ****Tracking – multiple gamma rays**
** ****Computing power**
** ****Cluster with 200 computer to process 20,000 ****γ****/sec**

- G. J. Schmid et al., Nucl. Instrum. Methods Phys. Res. A430, 69 (1999).
- K. Vetter et al., Nucl. Instrum. Methods Phys. Res. A452, 105 (2000).
- K. Vetter et al., Nucl. Instrum. Methods Phys. Res. A452, 223 (2000).
- M. Descovich et al., Nucl. Instrum. Methods Phys. Res. B241, 931 (2005).
- M. Descovich et al., Nucl. Instrum. Methods Phys. Res. A545, 199 (2005).
- M. Descovich et al., Nucl. Instrum. Methods Phys. Res. A553, 535 (2005).

**We have all the technology on hand**

## GRETINA is under construction

- Critical Decisions
** ****CD0 : Mission need ****	****	****	****Aug. 2003**
** ****CD1 : Preliminary Baseline Range   ****	****Feb. 2004**
** ****CD2A/CD3A : Start Construction**
**	**** ****long lead time items (Ge) ****	****June 2005**
** ****CD2B/CD3B : Start Construction ****	****July  2007**
** ****CD4 : Start of Operation ****	****	****Sept. 2010**

**CD0:  Approve mission need****	**
**CD1:  Approve preliminary baseline range****	****CD2:  Approve performance baseline range**
**CD3:  Approve start of construction****	****	****CD4:  Approve start of operation**

- Cover 1⁄4 of full solid angle
- Seven 4-cyrstal detector modules
- All the required software
- On schedule and on budget
- No technical problem

## GRETINA Status

**The first 4-crystal production **
**detector received 2006**

**Mechanical design completed 2006**** **

## GRETINA Status

- 100 MHz sampling rate
- 14 bit resolution
- 10 channels per board
- On board processing

**Mark III digitizer board produced 2007**

**Prototype computer farm assembled 2006**

- Eight  nodes
- 2GHz CPU
- 2Gbyte memory each
- LINUX
- 2 Tbyte disk storage

## GRETINA Status

**In-beam test carried out at 88” LBNL 2005**

- 3-crystal prototype
- 82Se + 12C @ 385 MeV
- 90Zr nuclei (v/c ~ 0.09)
- 2055 keV (10+8+) in 90Zr
- 0.75 Tbyte of data

**End-to-end analysis of in-beam data 2006**

- Signal decomposition
-  - use realistic basis signal
- Tracking
- Position resolution of 2.1 mm (RMS)
-    in all three dimensions

****

****** ****12 keV  FWHM**

## GRETINA Status

**In-beam test carried out at NSCL MSU 2006**

- 3-crystal prototype
- In coincidence with S800
-  - use time stamps
- 36Ar + Be @  86 MeV/A
- v/c = 0.4

**28****Si **

**E ********    (keV)**

**2****+**

**4****+**

- Data are being analyzed

## From GRETINA to GRETA

** ****GRETA will improve the power of GRETINA by Factors of 10 – 100.**
** ****GRETA is the most requested instrument at the next generation**
**      ****radioactive beam facility**
-       RIA Facility Workshop. East Lansing, Michigan,  March 9-13, 2004

## GRETA Cost and Schedule

**Start FY08, complete FY16**

** ****As fast as allowed by detector production schedule. **
** ****No gap between GRETINA and GRETA**
** ****Physics program to start 2008 with continue growth of capabilities.**
** ****Match RIA schedule, ready when RIA starts**
** ****Competing European project AGATA plan to be completed in 2016**

**Physics**
**Starts**
****

## GRETINA management structure 

***Working Groups and chairs***
- Physics	M. A. Riley
- Detector 	A. O. Macchiavelli
- Electronics 	D. C. Radford
- Software 	M. Cromaz
- Auxiliary Detectors	D.G. Sarantites

***                       ******Advisory Committee***
- Con Beausang**,** *University of Richmond*
- Doug Cline, *University of  Rochester*
- Thomas Glasmacher, *Michigan State University*
- C. Kim Lister, *Argonne National Laboratory*
- Augusto Macchiavelli,* Lawrence Berkeley Laboratory*
- David Radford (**Chair**), *Oak Ridge National Laboratory*
- Mark Riley, *Florida State University*
- Demetrios Sarantites, *Washington University*
- Kai Vetter,* Lawrence Livermore National Laboratory/UC Berkeley*

**  *****Management Advisory ***
***   ******Committee ***
*** ***
- James Symons (LBNL)
- Glenn Young (ORNL)
- Don Geesaman (ANL)
- Konrad Gelbke (MSU)

***       ******Project manager***
- I-Yang Lee (LBNL)

## Summary

***“******The detection of gamma-ray emissions from excited nuclei plays a vital and ubiquitous role in nuclear science. The physics justification for a 4************ tracking array is extremely compelling, spanning a wide range of fundamental questions in nuclear structure, nuclear astrophysics, and weak interactions. This new array would be a national resource that could be used at several existing stable and radioactive beam facilities, as well as at RIA.”***

**With GRETINA now under construction **
**we are moving towards this goal. **
**We strongly urge the timely completion**
**of the full 4******** system GRETA.**

**2002 Long Range Plan**