Title: Hammerhead, an ultrahigh resolution ePix camera for wavelength-dispersive spectrometers

Abstract

Wavelength-dispersive spectrometers (WDS) are often used in synchrotron and FEL applications where high energy resolution (in the order of eV) is important. Increasing WDS energy resolution requires increasing spatial resolution of the detectors in the dispersion direction. The common approaches are not ideal: using strip detectors loses the 2D position sensitivity (important for, e.g., background estimation) and the high counting rate; using pixel detectors with a small pitch results in complex charge sharing behaviour and typically have a small size. Developing pixel detectors with high aspect ratio and a small pitch in the wavelength dispersive direction would be ideal, however, it would require a substantial ASIC development. We present a new approach, with a novel sensor design using rectangular pixels with a high aspect ratio (between strips and pixels, further called “strixels”), and strixel redistribution to match the square pixel arrays of typical ASICs. This results in a sensor area of 17.4 mm × 77 mm, with a fine pitch of 25 µm in the horizontal direction resulting in 3072 columns and 176 rows. The sensors use ePix100 readout ASICs, leveraging their low noise (43 e^-, or 180 eV rms). We present results obtained with a Hammerhead ePix100 camera, showingmore » that the small pitch (25 µm) in the dispersion direction maximizes performance for both high and low photon occupancies, resulting in optimal WDS energy resolution. The low noise level at high photon occupancy allows precise photon counting, while at low occupancy, both the energy and the subpixel position can be reconstructed for every photon, allowing an ultrahigh resolution (in the order of 1 µm) in the dispersion direction and rejection of scattered beam and harmonics. Using strixel sensors with redistribution and flip-chip bonding to standard ePix readout ASICs results in ultrahigh position resolution (~1 µm) and low noise in WDS applications, leveraging the advantages of hybrid pixel detectors (high production yield, good availability, relatively inexpensive) while minimizing development complexity through sharing the ASIC, hardware, software and DAQ development with other versions of ePix cameras.« less

Authors:

Blaj, G. ^[1]; Bhogadi, D. ^[1]; Chang, C. ^[1]; Doering, D. ^[1]; Kenney, C. ^[1]; Kroll, T. ^[1]; Segal, J. ^[1]; Sokaras, D. ^[1]; Haller, G. ^[1]

---

+ Show Author Affiliations

1. SLAC National Accelerator Lab., Menlo Park, CA (United States)

Publication Date:

Wed Jan 16 00:00:00 EST 2019

Research Org.:

SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1529441

Alternate Identifier(s):

OSTI ID: 1605913

Report Number(s):

SLAC-PUB-17276
Journal ID: ISSN 0094-243X

Grant/Contract Number:  

AC02-76SF00515

Resource Type:

Accepted Manuscript

Journal Name:

AIP Conference Proceedings

Additional Journal Information:

Journal Volume: 2054; Journal ID: ISSN 0094-243X

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

47 OTHER INSTRUMENTATION