Application Oriented HPGe Detector Solutions

I. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

HPGe detectors vs. scintillation detectors

Advantages: Superior energy resolution

Energy range from

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

The HPGe detector has to be considered as a very complex instrument

n-type HPGe

p+ at HV (B) n+ at HV (Li)

n+ at ~ GND (Li) p+ at ~ GND (B, Au)

p-type HPGe

Bulletization

n-type HPGe

n+ at ~ GND (Li, a-Ge)

p+ at HV (B)

p-type HPGe

n+ at ~ GND (Li, a-Ge)

p+ at HV (B)

Guard

Ring

Coaxial P- or N- Type

Planar P- or N- Type

Typically Cold FET as an input stage.Resistive or pulsed Feedback?AC or DC coupled?

Geometry?

Cooling agent?

Window?

Radiation damages?

Low Background?

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

Criteria by choosing the detector – the

experiment/measurements specific

- Energy Range – determines the type of the crystal geometry. Low energies

(

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

Criteria by choosing the detector – the experiment/measurements specific

The standard detectors are in many cases not optimal for the application.

- Is the experiment at beam => all attitude orientation of the detector?

- Are the measurements “in situ” – portable detector? Crystal size rate 1:1

or similar.

- Low background solution – the quality of the crystal holder and detector

End Cap has to be chosen carefully. Copper or Creal? Also Carbon

fibers EndCap?

- Cryostat geometry – vertical dipstick, side looking or any suitable

shape…? What is the optimal solution for your application.

A specific solution for full body counting

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

- High count rate expected – has large impact on the efficiency and the type of the preamplifier. High

count rate may require pulsed feedback (transistor reset preamplifier) and/or small volume

(efficiency) detector.

- Multicrystal assembly (composite detector, used predominantly in the fundamental research

experiments. Coming soon in the medicine and other applications.) – may require AC coupling of the

preamplifier.

Criteria by choosing the detector – the experiment/measurements specific

The standard detectors are in many cases not optimal for the application.

U=Q/CF

Resistive Feedback

t = RFCF

U=Q/CF

Pulsed Feedback:

- Optical

- Transistor reset

Negative Feedback

CF

RF

CF

Courtesy of J.Kojouharova

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

- Is LN2 broadly available or one has to go to electrical

cooling? LN2 Recycler?

- Permitted by regulations use of LN2? Autofill?

Criteria by choosing the detector – the experiment/measurements specific

The standard detectors are in many cases not optimal for the application.

48 V power

supply

Test fixture

Cooling fins

Controller

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

- The HPGe detectors are more expensive as the scintillators.

One has to deal with ca. 600-1200 € per % efficiency for

standard geometry.

- Maintenance cost. A standard Pop Top Capsule needs vacuum

conditioning every 3-5 years, a standard VD detector every 5-7

years, GG detector as well.

- Autofill (if needed) piping – renewing every 6-12 months.

Criteria by choosing the detector – the cost factor

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

- Application oriented geometry and structure –

preferable as an optimal solution. Elevated cost,

however may have much higher operational capability.

Criteria by choosing the detector – the cost factor

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

The DESPEC – 0 Experiment setup – an application oriented solution

HISPEC (High-resolution

In-flight SPECtroscopy)

Runs AGATA as the basic

spectrometer

Super FRS

DESPEC (DEcay SPECtroscopy)

Runs DEGAS as the basic spectrometer –

DESPEC-0 Experiments

Collaboration of:

• Germany

• India

• Turkey

• Romania

• Spain

• Sweden

• UK

• Finland

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

The DESPEC – 0 Experiment setup – an application oriented solution

GALILEO Solution

DEGAS Solution

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

The DESPEC – 0 Experiment setup – an application oriented solution

Application Oriented HPGe

Detector SolutionsI. Kojouharov, GSI Darmstadt

BgNS Conference, 10-13

September, Sv.Vlas, Bulgaria

Thank you