NAHANT – Diane Mulcahy, who is employed as assistant principal at William A. Welch Sr. Elementary School in Peabody, has been hired as the new Johnson Elementary School principal.According to Interim Superintendent Joseph Lisi, the district signed a contract with Mulcahy on Friday afternoon and she is scheduled to start work on Jan. 28.”We’re very pleased she has agreed to accept the position,” he said.Mulcahy said she is looking forward to serving as principal of Johnson School.”It seems like a lovely opportunity,” she said. “I am really touched and very honored to have been chosen as the principal. It’s a lovely little school. I am looking forward to meeting all the staff members, children and parents.”Mulcahy, who is a Newburyport resident, has been working at William A. Welch Sr. Elementary School in Peabody since 2005. She said she has expertise in the areas of curriculum development, staff development, grant writing and school budgets.Lisi said the district had approximately 20 applicants for the principal position and the search committee winnowed the list down to six candidates before selecting two finalists.In August Diana Hennessey, who was a math teacher at Johnson Elementary School and retired last year, agreed to serve as interim principal until the school could find a replacement for Denise Littlefield.Littlefield was hired as superintendent/principal in July 2005 and she served as principal of Johnson Elementary School for several years prior to that. Her sudden resignation followed on the heels on a negative job performance evaluation by the School Committee.